Nevoid basal cell carcinoma syndrome (NBCCS) is characterized by the development of multiple jaw keratocysts, frequently beginning in the second decade of life, and/or basal cell carcinomas (BCCs) usually from the third decade onward. Approximately 60% of individuals have a recognizable appearance with macrocephaly, frontal bossing, coarse facial features, and facial milia. Most individuals have skeletal anomalies (e.g., bifid ribs, wedge-shaped vertebrae). Ectopic calcification, particularly in the falx, is present in more than 90% of affected individuals by age 20 years. Cardiac and ovarian fibromas occur in approximately 2% and 20% of individuals respectively. Approximately 5% of all children with NBCCS develop medulloblastoma (primitive neuroectodermal tumor), generally the desmoplastic subtype. The risk of developing medulloblastoma is substantially higher in individuals with an SUFU pathogenic variant (33%) than in those with a PTCH1 pathogenic variant (<2%). Peak incidence is at age one to two years. Life expectancy in NBCCS is not significantly different from average.

Focal dermal hypoplasia is a multisystem disorder characterized primarily by involvement of the skin, skeletal system, eyes, and face. Skin manifestations present at birth include atrophic and hypoplastic areas of skin; cutis aplasia; fat nodules in the dermis manifesting as soft, yellow-pink cutaneous nodules; and pigmentary changes. Verrucoid papillomas of the skin and mucous membranes may appear later. The nails can be ridged, dysplastic, or hypoplastic; hair can be sparse or absent. Limb malformations include oligo-/syndactyly and split hand/foot. Developmental abnormalities of the eye can include anophthalmia/microphthalmia, iris and chorioretinal coloboma, and lacrimal duct abnormalities. Craniofacial findings can include facial asymmetry, notched alae nasi, cleft lip and palate, and pointed chin. Occasional findings include dental anomalies, abdominal wall defects, diaphragmatic hernia, and renal anomalies. Psychomotor development is usually normal; some individuals have cognitive impairment.

Hallermann-Streiff syndrome is characterized by a typical skull shape (brachycephaly with frontal bossing), hypotrichosis, microphthalmia, cataracts, beaked nose, micrognathia, skin atrophy, dental anomalies, and proportionate short stature (Hallermann, 1948; Streiff, 1950; Francois, 1958). Mental retardation is present in a minority of cases (Gorlin et al., 1990).

A large brown, blue, or gray hamartoma of dermal melanocytes, usually on the shoulder and upper arm that is most commonly found in Asian populations and in females. It is sometimes associated with sensory changes in the involved skin area, but very rarely becomes cancerous.

Dubowitz syndrome (DS) is a rare multiple congenital syndrome characterized primarly by growth retardation, microcephaly, distinctive facial dysmorphism, cutaneous eczema, a mild to severe intellectual deficit and genital abnormalities.

CHD7 disorder encompasses the entire phenotypic spectrum of heterozygous CHD7 pathogenic variants that includes CHARGE syndrome as well as subsets of features that comprise the CHARGE syndrome phenotype. The mnemonic CHARGE syndrome, introduced in the premolecular era, stands for coloboma, heart defect, choanal atresia, retarded growth and development, genital hypoplasia, ear anomalies (including deafness). Following the identification of the genetic cause of CHD7 disorder, the phenotypic spectrum expanded to include cranial nerve anomalies, vestibular defects, cleft lip and/or palate, hypothyroidism, tracheoesophageal anomalies, brain anomalies, seizures, and renal anomalies. Life expectancy highly depends on the severity of manifestations; mortality can be high in the first few years when severe birth defects (particularly complex heart defects) are present and often complicated by airway and feeding issues. In childhood, adolescence, and adulthood, decreased life expectancy is likely related to a combination of residual heart defects, infections, aspiration or choking, respiratory issues including obstructive and central apnea, and possibly seizures. Despite these complications, the life expectancy for many individuals can be normal.

Cat eye syndrome (CES) is characterized clinically by the combination of coloboma of the iris and anal atresia with fistula, downslanting palpebral fissures, preauricular tags and/or pits, frequent occurrence of heart and renal malformations, and normal or near-normal mental development. A small supernumerary chromosome (smaller than chromosome 21) is present, frequently has 2 centromeres, is bisatellited, and represents an inv dup(22)(q11).

The branchiooculofacial syndrome (BOFS) is characterized by: branchial (cervical or infra- or supra-auricular) skin defects that range from barely perceptible thin skin or hair patch to erythematous "hemangiomatous" lesions to large weeping erosions; ocular anomalies that can include microphthalmia, anophthalmia, coloboma, and nasolacrimal duct stenosis/atresia; and facial anomalies that can include ocular hypertelorism or telecanthus, broad nasal tip, upslanted palpebral fissures, cleft lip or prominent philtral pillars that give the appearance of a repaired cleft lip (formerly called "pseudocleft lip") with or without cleft palate, upper lip pits, and lower facial weakness (asymmetric crying face or partial 7th cranial nerve weakness). Malformed and prominent pinnae and hearing loss from inner ear and/or petrous bone anomalies are common. Intellect is usually normal.

Mulibrey nanism (MUL) is a rare autosomal recessive growth disorder with prenatal onset, including occasional progressive cardiomyopathy, characteristic facial features, failure of sexual maturation, insulin resistance with type 2 diabetes, and an increased risk for Wilms tumor (summary by Hamalainen et al., 2006).

Jacobsen syndrome (JBS) is a contiguous gene deletion syndrome with major clinical features of growth retardation, psychomotor retardation, trigonocephaly, divergent intermittent strabismus, epicanthus, telecanthus, broad nasal bridge, short nose with anteverted nostrils, carp-shaped upper lip, retrognathia, low-set dysmorphic ears, bilateral camptodactyly, hammertoes, and isoimmune thrombocytopenia (Fryns et al., 1986, Epstein, 1986).

Curry-Jones syndrome (CRJS) is a multisystem disorder characterized by patchy skin lesions, polysyndactyly, diverse cerebral malformations, unicoronal craniosynostosis, iris colobomas, microphthalmia, and intestinal malrotation with myofibromas or hamartomas (summary by Twigg et al., 2016).

An extremely rare syndrome with characteristics of facial dysmorphism, severe intellectual deficiency, cardiac and intestinal anomalies, and growth retardation. Only four cases have been reported in the literature, in three unrelated families. Dysmorphic features include bilateral cleft lip and palate, bulbous nasal tip and eye anomalies. The condition seems to be inherited as an autosomal recessive trait.

Peters plus syndrome is characterized by anterior chamber eye anomalies, short limbs with broad distal extremities, characteristic facial features, cleft lip/palate, and variable developmental delay / intellectual disability. The most common anterior chamber defect is Peters' anomaly, consisting of central corneal clouding, thinning of the posterior cornea, and iridocorneal adhesions. Cataracts and glaucoma are common. Developmental delay is observed in about 80% of children; intellectual disability can range from mild to severe.

Microphthalmia-ankyloblepharon-intellectual disability syndrome is characterized by microphthalmia, ankyloblepharon and intellectual deficit. It has been described in seven male patients from two generations of a Northern Ireland family. The causative gene is localized to the Xq27-q28 region. The syndrome is transmitted as an X-linked recessive trait.

Microphthalmia with linear skin defects (MLS) syndrome is characterized by unilateral or bilateral microphthalmia and/or anophthalmia and linear skin defects, usually involving the face and neck, which are present at birth and heal with age, leaving minimal residual scarring. Other findings can include a wide variety of other ocular abnormalities (e.g., corneal anomalies, orbital cysts, cataracts), central nervous system involvement (e.g., structural anomalies, developmental delay, infantile seizures), cardiac concerns (e.g., hypertrophic or oncocytic cardiomyopathy, atrial or ventricular septal defects, arrhythmias), short stature, diaphragmatic hernia, nail dystrophy, hearing impairment, and genitourinary malformations. Inter- and intrafamilial variability is described.

The Richieri-Costa/Guion-Almeida syndrome is characterized by mild mental retardation, short stature, microbrachycephaly, ptosis, esotropia, cleft lip/palate (Richieri-Costa and Guion-Almeida, 1992).

Hajdu-Cheney syndrome (HJCYS) is a rare autosomal dominant skeletal disorder characterized by short stature, coarse and dysmorphic facies, bowing of the long bones, and vertebral anomalies. Facial features include hypertelorism, bushy eyebrows, micrognathia, small mouth with dental anomalies, low-set ears, and short neck. There is progressive focal bone destruction, including acroosteolysis and generalized osteoporosis. Additional and variable features include hearing loss, renal cysts, and cardiovascular anomalies (summary by Ramos et al., 1998; Simpson et al., 2011; Isidor et al., 2011).

Isolated gonadotropin-releasing hormone (GnRH) deficiency (IGD) is characterized by inappropriately low serum concentrations of the gonadotropins LH (luteinizing hormone) and FSH (follicle-stimulating hormone) in the presence of low circulating concentrations of sex steroids. IGD is associated with a normal sense of smell (normosmic IGD) in approximately 40% of affected individuals and an impaired sense of smell (Kallmann syndrome) in approximately 60%. IGD can first become apparent in infancy, adolescence, or adulthood. Infant boys with congenital IGD often have micropenis and cryptorchidism. Adolescents and adults with IGD have clinical evidence of hypogonadism and incomplete sexual maturation on physical examination. Adult males with IGD tend to have prepubertal testicular volume (i.e., <4 mL), absence of secondary sexual features (e.g., facial and axillary hair growth, deepening of the voice), decreased muscle mass, diminished libido, erectile dysfunction, and infertility. Adult females have little or no breast development and primary amenorrhea. Although skeletal maturation is delayed, the rate of linear growth is usually normal except for the absence of a distinct pubertal growth spurt.

SALL4-related disorders include Duane-radial ray syndrome (DRRS, Okihiro syndrome), acro-renal-ocular syndrome (AROS), and SALL4-related Holt-Oram syndrome (HOS) – three phenotypes previously thought to be distinct entities. DRRS is characterized by uni- or bilateral Duane anomaly and radial ray malformation that can include thenar hypoplasia and/or hypoplasia or aplasia of the thumbs, hypoplasia or aplasia of the radii, shortening and radial deviation of the forearms, triphalangeal thumbs, and duplication of the thumb (preaxial polydactyly). AROS is characterized by radial ray malformations, renal abnormalities (mild malrotation, ectopia, horseshoe kidney, renal hypoplasia, vesicoureteral reflux, bladder diverticula), ocular coloboma, and Duane anomaly. Rarely, pathogenic variants in SALL4 may cause clinically typical HOS (i.e., radial ray malformations and cardiac malformations without additional features).

A rare, congenital malformation syndrome characterized by the association of anterior ocular chamber cleavage disorder with developmental delay, short stature and congenital hypothyroidism. Additional manifestations include cerebellar hypoplasia, tracheal stenosis, narrow external auditory meatus, and hip dislocation. There have been no further description in the literature since 1995.

Congenital disorders of glycosylation (CDGs) are a genetically heterogeneous group of autosomal recessive disorders caused by enzymatic defects in the synthesis and processing of asparagine (N)-linked glycans or oligosaccharides on glycoproteins. Type I CDGs comprise defects in the assembly of the dolichol lipid-linked oligosaccharide (LLO) chain and its transfer to the nascent protein. These disorders can be identified by a characteristic abnormal isoelectric focusing profile of plasma transferrin (Leroy, 2006). CDG1D is a type I CDG that generally presents with severe neurologic involvement associated with dysmorphism and visual impairment. Liver involvement is sometimes present (summary by Marques-da-Silva et al., 2017). For a discussion of the classification of CDGs, see CDG1A (212065).

A rare disorder characterized by the partial separation of the cerebral hemispheres. It is associated with mutations in the SIX3 gene.

Pai syndrome is characterized by mild hypertelorism, midline cleft lip, nasal and facial polyps, pericallosal lipoma, ocular anomalies, and normal neuropsychologic development (Guion-Almeida et al., 2007).

Holoprosencephaly (HPE) is the most commonly occurring congenital structural forebrain anomaly in humans. HPE is associated with mental retardation and craniofacial malformations. Considerable heterogeneity in the genetic causes of HPE has been demonstrated (Ming et al., 2002). For general phenotypic information and a discussion of genetic heterogeneity of holoprosencephaly, see HPE1 (236100).

Congenital disorder of glycosylation type Ii (CDG1I) is a rare autosomal recessive disorder characterized by neurologic involvement, including a convulsive syndrome of unknown origin, axial hypotonia, and mental and motor regression (summary by Papazoglu et al., 2021). For a general discussion of CDGs, see CDG1A (212065).

Corpus callosum agenesis-intellectual disability-coloboma-micrognathia syndrome is a developmental anomalies syndrome characterized by coloboma of the iris and optic nerve, facial dysmorphism (high forehead, microretrognathia, low-set ears), intellectual deficit, agenesis of the corpus callosum (ACC), sensorineural hearing loss, skeletal anomalies and short stature.

Terminal osseous dysplasia is an X-linked dominant male-lethal disease characterized by skeletal dysplasia of the limbs, pigmentary defects of the skin, and recurrent digital fibroma during infancy (Sun et al., 2010).

Oculofaciocardiodental (OFCD) syndrome is a condition that affects the development of the eyes (oculo-), facial features (facio-), heart (cardio-), and teeth (dental). \n\nThe eye abnormalities associated with OFCD syndrome can affect one or both eyes. Many people with this condition are born with eyeballs that are abnormally small (microphthalmia). Other eye problems can include clouding of the lens (cataract) and a high risk of glaucoma, an eye disease that increases the pressure in the eye. These abnormalities can lead to vision loss or blindness.\n\nPeople with OFCD syndrome often have a long, narrow face with distinctive facial features, including deep-set eyes, droopy eyelids (ptosis), and a nose with a high bridge and broad tip. Affected individuals may have a split (cleft) in their nose or in the roof of their mouth (cleft palate).\n\nHeart defects are another common feature of OFCD syndrome. Babies with this condition may be born with a hole between two chambers of the heart (an atrial or ventricular septal defect) or a leak in one of the valves that controls blood flow through the heart (mitral valve prolapse).\n\nTeeth with very large roots (radiculomegaly) are characteristic of OFCD syndrome. Additional dental abnormalities can include the delayed loss of primary (baby) teeth, missing or abnormally small teeth, delayed teething (dentition), misaligned teeth, and defective tooth enamel.\n\nIndividuals with OFCD syndrome can have additional features, such as skeletal abnormalities (typically affecting the toes), hearing loss, and intellectual disabilities. 

A multisystem malformation syndrome that has been reported in about 10 patients. The clinical features include bilateral anophthalmia, abnormal nares, central nervous system anomalies, and neurodevelopmental delay. Additional features include brachycephaly and other facial anomalies. Non-facial anomalies have also been reported: postaxial polydactyly, genital hypoplasia. All cases reported so far have been sporadic, suggesting that the syndrome may be due to a new dominant mutation.

Stromme syndrome is an autosomal recessive congenital disorder affecting multiple systems with features of a ciliopathy. Affected individuals typically have some type of intestinal atresia, variable ocular abnormalities, microcephaly, and sometimes involvement of other systems, including renal and cardiac. In some cases, the condition is lethal in early life, whereas other patients show normal survival with or without mild cognitive impairment (summary by Filges et al., 2016).

Baraitser-Winter cerebrofrontofacial (BWCFF) syndrome is a multiple congenital anomaly syndrome characterized by typical craniofacial features and intellectual disability. Many (but not all) affected individuals have pachygyria that is predominantly frontal, wasting of the shoulder girdle muscles, and sensory impairment due to iris or retinal coloboma and/or sensorineural deafness. Intellectual disability, which is common but variable, is related to the severity of the brain malformations. Seizures, congenital heart defects, renal malformations, and gastrointestinal dysfunction are also common.

Mowat-Wilson syndrome (MWS) is characterized by distinctive facial features (widely spaced eyes, broad eyebrows with a medial flare, low-hanging columella, prominent or pointed chin, open-mouth expression, and uplifted earlobes with a central depression), congenital heart defects with predilection for abnormalities of the pulmonary arteries and/or valves, Hirschsprung disease or chronic constipation, genitourinary anomalies (particularly hypospadias in males), and hypogenesis or agenesis of the corpus callosum. Most affected individuals have moderate-to-severe intellectual disability. Speech is typically limited to a few words or is absent, with relative preservation of receptive language skills. Growth restriction with microcephaly and seizure disorder are also common. Most affected people have a happy demeanor and a wide-based gait that can sometimes be confused with Angelman syndrome.

Donnai-Barrow syndrome (DBS) is characterized by typical craniofacial features (large anterior fontanelle, wide metopic suture, widow's peak, markedly widely spaced eyes, enlarged globes, downslanted palpebral fissures, posteriorly rotated ears, depressed nasal bridge, and short nose. Ocular complications include high myopia, retinal detachment, retinal dystrophy, and progressive vision loss. Additional common features include agenesis of the corpus callosum, sensorineural hearing loss, intellectual disability, and congenital diaphragmatic hernia and/or omphalocele. Both inter- and intrafamilial phenotypic variability are observed.

Temtamy syndrome is a mental retardation/multiple congenital anomaly syndrome characterized by variable craniofacial dysmorphism, ocular coloboma, seizures, and brain abnormalities, including abnormalities of the corpus callosum and thalamus (summary by Akizu et al., 2013).

Mutations in the MAF gene have been found to cause multiple types of cataract, which have been described as cortical pulverulent, lamellar, nuclear, nuclear pulverulent, nuclear stellate, anterior polar, anterior subcapsular, posterior subcapsular, and cerulean. In some cases, the cataracts are of juvenile onset. The preferred title of this entry was formerly 'Cataract, Pulverulent, Juvenile-Onset,' with an 'Included' title/symbol of 'Cataract, Congenital, Cerulean Type, 4; CCA4.'

Mutations in the CRYAA gene have been found to cause multiple types of cataract, which have been described as nuclear, zonular central nuclear, laminar, lamellar, anterior polar, posterior polar, cortical, embryonal, anterior subcapsular, fan-shaped, and total. Cataract associated with microcornea, sometimes called the cataract-microcornea syndrome, is also caused by mutation in the CRYAA gene. Both autosomal dominant and autosomal recessive modes of inheritance have been reported. The symbol CATC1 was formerly used for the autosomal recessive form of cataract caused by mutation in the CRYAA gene.

An exceedingly rare genetic neurological and developmental disorder reported in a very small number of patients with a poorly defined phenotype including iris coloboma, short stature, obesity, hypogonadism, post axial polydactyly, and intellectual disability. Hydrocephalus and facial dysostosis were also reported. The syndrome shares features with Bardet-Biedl syndrome. There have been no new descriptions in the literature since 1997.

Any microphthalmia, isolated, with coloboma in which the cause of the disease is a mutation in the VSX2 gene.

Colobomatous macrophthalmia with microcornea (MACOM) is an autosomal dominant eye malformation characterized by microcornea with increased axial length, coloboma of the iris and optic disc, and severe myopia (summary by Beleggia et al., 2015).

An exceedingly rare genetic disorder with characteristics of cutaneous pigmentation anomalies, ocular disorders and hearing loss. The syndrome was described in 1990 in two patients from the same Yemenite family. A brother and sister were described as having cutaneous patchy hypo and hyperpigmentation on the trunk and extremities, gray hair, white brows and lashes. Ocular manifestations were microcornea, coloboma and abnormalities of the anterior chamber of the eye. Both patients had severe hearing loss and dental abnormalities. Intelligence was reported to be normal. Their parents were unaffected and possibly consanguineous. The cause of this syndrome has not been determined. The inheritance pattern appears to be autosomal recessive.

This syndrome has characteristics of holoprosencephaly, predominantly radial limb deficiency (absent thumbs, phocomelia), heart defects, kidney malformations and absence of gallbladder. It has been described in two families (with at least seven affected persons). Variable manifestations include vertebral anomalies, cleft lip/palate, microphthalmia, absent nose, dysplastic ears, hearing loss, colobomas of the iris and retina and/or bifid uvula. Inheritance is likely to be autosomal dominant with variable expressivity.

Scalp-ear-nipple syndrome is characterized by aplasia cutis congenita of the scalp, breast anomalies that range from hypothelia or athelia to amastia, and minor anomalies of the external ears. Less frequent clinical characteristics include nail dystrophy, dental anomalies, cutaneous syndactyly of the digits, and renal malformations. Penetrance appears to be high, although there is substantial variable expressivity within families (Marneros et al., 2013).

A rare focal skeletal dysostosis with characteristics of symmetrical hypoplasia of the scapulae and the iliac wings of the pelvis. Approximately 10 patients have been reported so far. Additional skeletal abnormalities may include hypoplasia of the clavicles, ribs, femora and fibula, together with spina bifida and prominent lumbar lordosis. Eye anomalies (coloboma of iris and retina) have occasionally been reported. Intelligence is described as normal. Pelvis-shoulder dysplasia seems to be a genetically heterogeneous disorder but no causative genes have been identified so far.

Wolf-Hirschhorn syndrome is a congenital malformation syndrome characterized by pre- and postnatal growth deficiency, developmental disability of variable degree, characteristic craniofacial features ('Greek warrior helmet' appearance of the nose, high forehead, prominent glabella, hypertelorism, high-arched eyebrows, protruding eyes, epicanthal folds, short philtrum, distinct mouth with downturned corners, and micrognathia), and a seizure disorder (Battaglia et al., 2008).

Any microphthalmia, isolated, with coloboma in which the cause of the disease is a mutation in the SHH gene.

Persistent hyperplastic primary vitreous (PHPV), also termed 'persistent fetal vasculature,' is a developmental malformation of the eye in which the primary vitreous fails to regress in utero, resulting in the presence of a retrolental fibrovascular membrane with persistence of the posterior portion of the tunica vasculosa lentis and hyaloid artery. This abnormality is usually unilateral and associated with microphthalmia, cataract, glaucoma, and congenital retinal nonattachment (see Haddad et al., 1978; Khaliq et al., 2001; Prasov et al., 2012). PHPV shares phenotypic overlap with Norrie disease (310600). Genetic Heterogeneity of Persistent Hyperplastic Primary Vitreous A dominant form of PHPV has been described (PHPVAD; 611308).

Kahrizi syndrome is an autosomal recessive neurodevelopmental disorder characterized by mental retardation, cataracts, coloboma, kyphosis, and coarse facial features (summary by Kahrizi et al., 2009). See also congenital disorder of glycosylation type Iq (CDG1Q; 612379), an allelic disorder with overlapping features.

Oculoauricular syndrome (OCACS) is characterized by complex ocular anomalies, including congenital cataract, anterior segment dysgenesis, iris coloboma, and early-onset retinal dystrophy, and dysplastic ears with abnormal external ear cartilage (summary by Gillespie et al., 2015).

A very rare form of stromal corneal dystrophy with characteristics of irregular amorphous sheet-like opacities in the posterior corneal stroma and in the Descemet membrane along with mildly impaired vision. Prevalence of this form of corneal dystrophy is not known. To date cases have been reported primarily in the USA. Patients usually develop corneal abnormalities in infancy or childhood. The condition is non-progressive or slowly progressive. Unlike other corneal dystrophies, non-corneal manifestations have been observed and include abnormalities of the iris including iridocorneal adhesions, corectopia, and pseudopolycoria. An autosomal dominant pattern of inheritance has been reported.

The features of frontofacionasal dysplasia include blepharophimosis, lower lid lagophthalmos, primary telecanthus, S-shaped palpebral fissures, facial hypoplasia, eyelid coloboma, widow's peak, cranium bifidum occultum, frontal lipoma, nasal hypoplasia, deformed nostrils, bifid nose, and cleft of lip, premaxilla, palate, and uvula (White et al., 1991). Also see frontonasal dysplasia (136760).

Klippel-Feil syndrome (KFS) is a congenital anomaly characterized by a defect in the formation or segmentation of the cervical vertebrae, resulting in a fused appearance. The clinical triad consists of short neck, low posterior hairline, and limited neck movement, although less than 50% of patients demonstrate all 3 clinical features (Tracy et al., 2004). For a general description and a discussion of genetic heterogeneity of Klippel-Feil syndrome, see KFS1 (118100).

The chromosome 13q14 deletion syndrome is characterized by retinoblastoma (180200), variable degrees of mental impairment, and characteristic facial features, including high forehead, prominent philtrum, and anteverted earlobes (summary by Caselli et al., 2007).

Anterior segment dysgeneses (ASGD or ASMD) are a heterogeneous group of developmental disorders affecting the anterior segment of the eye, including the cornea, iris, lens, trabecular meshwork, and Schlemm canal. The clinical features of ASGD include iris hypoplasia, an enlarged or reduced corneal diameter, corneal vascularization and opacity, posterior embryotoxon, corectopia, polycoria, an abnormal iridocorneal angle, ectopia lentis, and anterior synechiae between the iris and posterior corneal surface (summary by Cheong et al., 2016). In sclerocornea there is congenital, nonprogressive corneal opacification that may be peripheral, sectoral, or central in location. Visual prognosis is related to the central corneal involvement. The cornea has a flat curvature. The majority of cases are bilateral (summary by Smith and Traboulsi, 2012). Isolated sclerocornea is caused by displacement of the limbal arcades and may be associated with cornea plana; in this condition, the anterior chamber is visible and the eye is not microphthalmic. In complex sclerocornea, however, corneal opacification is associated with microphthalmia, cataract, and/or infantile glaucoma. The central cornea is usually relatively clear, but the thickness is normal or increased, never reduced (summary by Nischal, 2007).

Any microphthalmia, isolated, with coloboma in which the cause of the disease is a mutation in the ABCB6 gene.

Syndrome that has characteristics of dysmorphic features and intellectual deficit. It has been described in seven patients within one family. 17q11.2 microduplication encompasses the NF1 region. The underlying mechanism may be non-allelic homologous recombination. The study of pedigree suggests that this microduplication segregates within the family for at least two generations. Two patients displayed a normal clinical presentation, suggesting an autosomal dominant pattern of inheritance with incomplete penetrance.

MCOPCB9 is characterized by microphthalmia and coloboma (Aldahmesh et al., 2012). MCOPS15 is characterized by microphthalmia and/or coloboma, with developmental delay in which speech appears to be more severely affected than motor abilities. Additional ocular anomalies that have been observed include ptosis, keyhole-shaped pupils, microcornea, sclerocornea, and anterior segment dysgenesis (Chassaing et al., 2016; Stephen et al., 2018; Singh et al., 2019). For a discussion of genetic heterogeneity of colobomatous microphthalmia, see MCOPCB1 (300345). For a discussion of genetic heterogeneity of syndromic microphthalmia, see MCOPS1 (309800).

Progressive retinal dystrophy due to retinol transport defect is a rare, genetic, metabolite absorption and transport disorder characterized by progressive rod-cone dystrophy, usually presenting with impaired night vision in childhood, progressive loss of visual acuity and severe retinol deficiency without keratomalacia. Association with ocular colobomas, severe acne and hypercholesterolemia has been reported.

Congenital hydrocephalus-2 (HYC2) is a congenital disorder with onset in utero. Affected individuals have hydrocephalus with variably dilated ventricles and variable neurologic sequelae. Some individuals have other brain abnormalities, including lissencephaly, thinning of the corpus callosum, and neuronal heterotopia. Most patients have delayed motor development and some have delayed intellectual development and/or seizures. Additional congenital features, including cardiac septal defects, iris coloboma, and nonspecific dysmorphic features, may be observed. Some patients die in utero, in infancy, or in early childhood, whereas others have long-term survival (summary by Shaheen et al., 2017). For a discussion of genetic heterogeneity of congenital hydrocephalus, see 233600.

Meckel syndrome, also known as Meckel-Gruber syndrome, is a severe pleiotropic autosomal recessive developmental disorder caused by dysfunction of primary cilia during early embryogenesis. There is extensive clinical variability and controversy as to the minimum diagnostic criteria. Early reports, including that of Opitz and Howe (1969) and Wright et al. (1994), stated that the classic triad of Meckel syndrome comprises (1) cystic renal disease; (2) a central nervous system malformation, most commonly occipital encephalocele; and (3) polydactyly, most often postaxial. However, based on a study of 67 patients, Salonen (1984) concluded that the minimum diagnostic criteria are (1) cystic renal disease; (2) CNS malformation, and (3) hepatic abnormalities, including portal fibrosis or ductal proliferation. In a review of Meckel syndrome, Logan et al. (2011) stated that the classic triad first described by Meckel (1822) included occipital encephalocele, cystic kidneys, and fibrotic changes to the liver. Genetic Heterogeneity of Meckel Syndrome See also MKS2 (603194), caused by mutation in the TMEM216 gene (613277) on chromosome 11q12; MKS3 (607361), caused by mutation in the TMEM67 gene (609884) on chromosome 8q; MKS4 (611134), caused by mutation in the CEP290 gene (610142) on chromosome 12q; MKS5 (611561), caused by mutation in the RPGRIP1L gene (610937) on chromosome 16q12; MKS6 (612284), caused by mutation in the CC2D2A gene (612013) on chromosome 4p15; MKS7 (267010), caused by mutation in the NPHP3 (608002) gene on chromosome 3q22; MKS8 (613885), caused by mutation in the TCTN2 gene (613846) on chromosome 12q24; MKS9 (614209), caused by mutation in the B9D1 gene (614144) on chromosome 17p11; MKS10 (614175), caused by mutation in the B9D2 gene (611951) on chromosome 19q13; MKS11 (615397), caused by mutation in the TMEM231 gene (614949) on chromosome 16q23; MKS12 (616258), caused by mutation in the KIF14 gene (611279) on chromosome 1q32; MKS13 (617562), caused by mutation in the TMEM107 gene (616183) on chromosome 17p13; and MKS14 (619879), caused by mutation in the TXNDC15 gene (617778) on chromosome 5q31.

A rare, genetic, multiple congenital anomalies/dysmorphic syndrome characterized by uveal coloboma (typically bilateral) variably associated with cleft lip, palate and/or uvula, hearing impairment, and intellectual disability. The spectrum of eye involvement is also variable and includes iris coloboma extending to the choroid, disc, and/or macula, microphthalmia, cataract, and extraocular movement impairment.

X-linked colobomatous microphthalmia-microcephaly-intellectual disability-short stature syndrome is a rare syndromic microphthalmia disorder characterized by microphthalmia with coloboma (which may involve the iris, cilary body, choroid, retina and/or optic nerve), microcephaly, short stature and intellectual disability. Other eye abnormalities such as pendular nystagmus, esotropia and ptosis may also be present. Additional associated abnormalities include kyphoscoliosis, anteverted pinnae with minimal convolutions, diastema of the incisors and congenital pes varus.

Coloboma is an ocular birth defect resulting from abnormal development of the eye during embryogenesis. It is defined as a congenital defect in any ocular tissue, typically presenting as absent tissue or a gap, at a site consistent with aberrant closure of the optic fissure. Failure of fusion can lead to coloboma of 1 or multiple regions of the inferior portion of the eye affecting any part of the globe traversed by the fissure, from the iris to the optic nerve, including the ciliary body, retina, and choroid. Coloboma is also frequently associated with small (microphthalmic) or absent (anophthalmic) eyes as part of an interrelated spectrum of developmental eye anomalies, and can affect either one or both eyes (summary by Kelberman et al., 2014). For a discussion of genetic heterogeneity of ocular coloboma, see 120200.

Any microphthalmia, isolated, with coloboma in which the cause of the disease is a mutation in the RBP4 gene.

White-Sutton syndrome is a neurodevelopmental disorder characterized by a wide spectrum of cognitive dysfunction, developmental delays (particularly in speech and language acquisition), hypotonia, autism spectrum disorder, and other behavioral problems. Additional features commonly reported include seizures, refractive errors and strabismus, hearing loss, sleep disturbance (particularly sleep apnea), feeding and gastrointestinal problems, mild genital abnormalities in males, and urinary tract involvement in both males and females.

A rare genetic eye disease with characteristics of optic disc anomalies (bilateral colobomatous optic discs, retinal vessels arising from the peripheral optic disc) and macular atrophy. Peripapillary chorioretinal atrophy and chorioretinal and iris coloboma have also been described. Patients present with horizontal nystagmus and poor visual acuity.

Retinal dystrophy and iris coloboma with or without cataract (RDICC) is characterized by early-onset chorioretinal dystrophy that is variably associated with other eye anomalies, including iris coloboma and/or congenital or early-onset cataract. Congenital glaucoma has also been observed (Conte et al., 2015; Jedlickova et al., 2023).

Witteveen-Kolk syndrome (WITKOS) is an autosomal dominant disorder with characteristic distinctive facial features, microcephaly, short stature, and mildly impaired intellectual development with delayed cognitive and motor development and subtle anomalies on MRI-brain imaging (summary by Balasubramanian et al., 2021).

A rare developmental defect with connective tissue involvement and characteristics of joint hyperextensibility and multiple dislocations of large joints, severe myopia and short stature. Other common features include retinal detachment, iris and chorioretinal coloboma, kyphoscoliosis and other spine deformities, pectus carinatum, talipes equinovarus and progressive hearing loss.

Developmental and epileptic encephalopathy (DEE93) is an autosomal dominant neurologic disorder characterized by delayed psychomotor development, early-onset refractory seizures, and impaired intellectual development. The severity of the phenotype is highly variable: some patients may be nonverbal and nonambulatory with spastic quadriparesis and poor eye contact, whereas others have moderate intellectual disability (summary by Fassio et al., 2018). For a discussion of genetic heterogeneity of DEE, see 308350.

Nizon-Isidor syndrome (NIZIDS) is a neurodevelopmental disorder characterized by global developmental delay, mildly delayed walking, poor speech and language, variably impaired intellectual development, and behavioral abnormalities, such as autistic features or attention deficit-hyperactivity disorder (ADHD). Some patients may have additional features, including nonspecific facial dysmorphism, gastrointestinal difficulties, distal hand anomalies, and thin corpus callosum on brain imaging (summary by Nizon et al., 2019).

Developmental delay, impaired speech, and behavioral abnormalities (DDISBA) is characterized by global developmental delay apparent from early childhood. Intellectual disability can range from mild to severe. Additional variable features may include dysmorphic facial features, seizures, hypotonia, motor abnormalities such as Tourette syndrome or dystonia, and hearing loss (summary by Cousin et al., 2021).

Hijazi-Reis syndrome (HIJRS) is an X-linked dominant disorder characterized by global developmental delay with hypotonia, motor delay, impaired intellectual development, and speech and language delay. Affected individuals also have dysmorphic facial features, gastrointestinal issues, and ocular anomalies. Rare patients have seizures (Hijazi et al., 2022).

Branchial arch abnormalities, choanal atresia, athelia, hearing loss, and hypothyroidism syndrome (BCAHH) is an autosomal dominant disorder characterized by choanal atresia, athelia or hypoplastic nipples, branchial sinus abnormalities, neck pits, lacrimal duct anomalies, hearing loss, external ear malformations, and thyroid abnormalities. Additional features may include developmental delay, impaired intellectual development, and growth failure/retardation (summary by Cuvertino et al., 2020 and Baldridge et al., 2020).

Neurodevelopmental disorder with intracranial hemorrhage, seizures, and spasticity (NEDIHSS) is an autosomal recessive disorder characterized by prenatal or neonatal onset of intracranial hemorrhage, usually with ventriculomegaly and calcifications, resulting in parenchymal brain damage. Some affected individuals have symptoms incompatible with life and die in utero. Those that survive show profound global developmental delay with almost no motor or cognitive skills, hypotonia, spasticity, and seizures. Other features may include facial dysmorphism, retinal vascular abnormalities, and poor overall growth. The pathogenesis of the disease likely results from dysfunction of vascular endothelial cells in the brain (Lecca et al., 2023).

Thrombocytopenia-11 with multiple congenital anomalies and dysmorphic facies (THC11) is a syndromic disorder characterized by dysmorphic facial features, multiple congenital anomalies that may involve the heart, brain, genitourinary, endocrine, and/or skeletal systems, chronic and persistent thrombocytopenia, sometimes with leukopenia or anemia, poor growth with microcephaly, hypotonia, and mildly impaired intellectual development or learning disabilities. The disorder results from constitutive activation of the RAS signaling pathway and can be considered a RASopathy (Niemann et al., 2020; Miller et al., 2022). For a discussion of genetic heterogeneity of thrombocytopenia, see 313900.

Microphthalmia/coloboma-11 (MCOPCB11) is characterized by ocular coloboma and related phenotypes such as inferior chorioretinal hypoplasia and/or optic disc hypoplasia, with occasional microphthalmia or high myopia. Incomplete penetrance as well as intrafamilial and intraindividual phenotypic variability have been observed (Liu et al., 2016; Aubert-Mucca et al., 2021; Jiang et al., 2021; Holt et al., 2022). For a discussion of genetic heterogeneity of colobomatous microphthalmia, see MCOPCB1 (300345).

Neuroocular syndrome-1 (NOC1) encompasses a broad spectrum of overlapping anomalies, with developmental delay or impaired intellectual development as a consistent finding. Eye abnormalities show marked variability in the type and severity of defects, and include anophthalmia, microphthalmia, and coloboma. Other common systemic features include congenital heart and kidney defects, hypotonia, failure to thrive, and microcephaly (summary by Chowdhury et al., 2021). Genetic Heterogeneity of Neuroocular Syndrome See also NOC2 (168885), caused by mutation in the DAGLA gene (614015) on chromosome 11q12.