MedGen

Spinocerebellar ataxia type 7 (SCA7) comprises a phenotypic spectrum ranging from adolescent- or adult-onset progressive cerebellar ataxia and cone-rod retinal dystrophy to infantile or early-childhood onset with multiorgan failure, an accelerated course, and early death. Anticipation in this nucleotide repeat disorder may be so dramatic that within a family a child with infantile or early-childhood onset may be diagnosed with what is thought to be an unrelated neurodegenerative disorder years before a parent or grandparent with a CAG repeat expansion becomes symptomatic. In adolescent-onset SCA7, the initial manifestation is typically impaired vision, followed by cerebellar ataxia. In those with adult onset, progressive cerebellar ataxia usually precedes the onset of visual manifestations. While the rate of progression varies in these two age groups, the eventual result for almost all affected individuals is loss of vision, severe dysarthria and dysphagia, and a bedridden state with loss of motor control. [from GeneReviews]

Pseudoxanthoma elasticum (PXE) is a systemic disorder that affects the elastic tissue of the skin, the eye, and vascular system. Individuals most commonly present with angioid streaks of the retina found on routine eye examination or associated with retinal hemorrhage and/or characteristic papules in the skin. The most frequent cause of morbidity and disability in PXE is reduced vision due to complications of subretinal neovascularizations and macular atrophy. Other manifestations include premature gastrointestinal angina and/or bleeding, intermittent claudication of arm and leg muscles, stroke, renovascular hypertension, and cardiovascular complications (angina/myocardial infarction). Most affected individuals live a normal life span. [from GeneReviews]

The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The clinical course includes progressive dementia, seizures, and progressive visual failure (Mole et al., 2005). The hallmark of CLN3 is the ultrastructural pattern of lipopigment with a 'fingerprint' profile, which can have 3 different appearances: pure within a lysosomal residual body; in conjunction with curvilinear or rectilinear profiles; and as a small component within large membrane-bound lysosomal vacuoles. The combination of fingerprint profiles within lysosomal vacuoles is a regular feature of blood lymphocytes from patients with CLN3 (Mole et al., 2005). For a general phenotypic description and a discussion of genetic heterogeneity of CLN, see CLN1 (256730). [from OMIM]

Stargardt disease-1 (STGD1) is an autosomal recessive retinal disease that usually presents as a juvenile-onset macular dystrophy with rapid central visual impairment, progressive bilateral atrophy of the foveal retinal pigment epithelium, and the frequent appearance of yellowish flecks, defined as lipofuscin deposits, around the macula and/or in the central and near-peripheral areas of the retina (summary by Lee et al., 2021). Genetic Heterogeneity of Stargardt Disease Stargardt disease-3 (STGD3; 600110) is caused by mutation in the ELOVL4 gene (605512) on chromosome 6q14, and Stargardt disease-4 (STGD4; 603786) is caused by mutation in the PROM1 gene (604365) on chromosome 4. A locus for Stargardt disease mapped to chromosome 13q34 and designated STGD2 was found to be in error; the disorder in the family in which the linkage was made was correctly mapped to chromosome 6q14 (STGD3). Fundus flavimaculatus (FFM) is an allelic subtype of Stargardt disease that has been associated with mutation in the ABCA4 gene and the PRPH2 gene (179605). FFM has a later age of onset. If loss of visual acuity begins in the first 2 decades, the designation Stargardt disease is preferred; if it begins later in life and has a more progressive course, the term FFM is preferred (Weleber, 1994). An early-onset severe form of retinal dystrophy (CORD3; 604116) is caused by homozygous null mutations in the ABCA4 gene. [from OMIM]

Age-related macular degeneration (ARMD) is a progressive degeneration of photoreceptors and underlying retinal pigment epithelium (RPE) cells in the macula region of the retina. It is a highly prevalent disease and a major cause of blindness in the Western world. Drusen, pale excrescences of variable size, and other deposits accumulate below the RPE on the Bruch membrane; clinical and histopathologic investigations have shown that these extracellular deposits are the hallmark of early ARMD. As ARMD advances, areas of geographic atrophy of the RPE can cause visual loss, or choroidal neovascularization can occur to cause wet, or exudative, ARMD with accompanying central visual loss (summary by De et al., 2007). Genetic Heterogeneity of Age-Related Macular Degeneration ARMD2 (153800) is associated with mutation in the ABCR gene (601691) on chromosome 1p, and ARMD3 (608895) is caused by mutation in the FBLN5 gene (604580) on chromosome 14q31. Up to 50% of the attributable risk of age-related macular degeneration (ARMD4; 610698) appears to be explained by a polymorphism in the CFH gene (134370.0008). ARMD5 (613761) and ARMD6 (613757) are associated with mutation in the ERCC6 (609413) and RAX2 (610362) genes, respectively. ARMD7 (610149) and ARMD8 (613778), which both represent susceptibility linked to chromosome 10q26, are associated with single-nucleotide polymorphisms in the HTRA1 (602194) and ARMS2 (611313) genes, respectively. ARMD9 (611378) is associated with single-nucleotide polymorphisms in the C3 gene (120700). ARMD10 (611488) maps to chromosome 9q32 and may be associated with a polymorphism in the TLR4 gene (603030). ARMD11 (611953) is association with variation in the CST3 gene (604312); ARMD12 (613784) with variation in the CX3CR1 gene (601470); and ARMD13 (615439) with variation in the CFI gene (217030). ARMD14 (615489) is associated with variation in or near the C2 (613927) and CFB (138470) genes on chromosome 6p21. ARMD15 (615591) is associated with variation in the C9 gene (120940). There is evidence for a form of ARMD caused by mutation in the mitochondrial gene MTTL1 (590050). A haplotype carrying deletion of the complement factor H-related genes CFHR1 (134371) and CFHR3 (605336) is also associated with reduced risk of ARMD. Lotery and Trump (2007) reviewed the molecular biology of age-related macular degeneration and tabulated the genes associated with ARMD, including those with only positive findings versus genes for which conflicting results have been found. [from OMIM]

The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The lipopigment pattern seen most often in CLN1 is referred to as granular osmiophilic deposits (GROD). The patterns most often observed in CLN2 and CLN3 are 'curvilinear' and 'fingerprint' profiles, respectively. CLN4, CLN5, CLN6, CLN7, and CLN8 show mixed combinations of granular, curvilinear, fingerprint, and rectilinear profiles. The clinical course includes progressive dementia, seizures, and progressive visual failure (Mole et al., 2005). Zeman and Dyken (1969) referred to these conditions as the 'neuronal ceroid lipofuscinoses.' Goebel (1995) provided a comprehensive review of the NCLs and noted that they are possibly the most common group of neurodegenerative diseases in children. Mole et al. (2005) provided a detailed clinical and genetic review of the neuronal ceroid lipofuscinoses. Genetic Heterogeneity of Neuronal Ceroid Lipofuscinosis See also CLN2 (204500), caused by mutation in the TPP1 gene (607998) on chromosome 11p15; CLN3 (204200), caused by mutation in the CLN3 gene (607042) on 16p12; CLN4 (162350), caused by mutation in the DNAJC5 gene (611203) on 20q13; CLN5 (256731), caused by mutation in the CLN5 gene (608102) on 13q22; CLN6A (601780) and CLN6B (204300), both caused by mutation in the CLN6 gene (606725) on 15q21; CLN7 (610951), caused by mutation in the MFSD8 gene (611124) on 4q28; CLN8 (600143) and the Northern epilepsy variant of CLN8 (610003), both caused by mutation in the CLN8 gene (607837) on 8p23; CLN10 (610127), caused by mutation in the CTSD gene (116840) on 11p15; CLN11 (614706), caused by mutation in the GRN gene (138945) on 17q21; CLN13 (615362), caused by mutation in the CTSF gene (603539) on 11q13; and CLN14 (611726), caused by mutation in the KCTD7 gene (611725) on 7q11. CLN9 (609055) has not been molecularly characterized. A disorder that was formerly designated neuronal ceroid lipofuscinosis-12 (CLN12) is now considered to be a variable form of Kufor-Rakeb syndrome (KRS; 606693). [from OMIM]

Sjogren-Larsson syndrome (SLS) is an autosomal recessive, early childhood-onset disorder characterized by ichthyosis, impaired intellectual development, spastic paraparesis, macular dystrophy, and leukoencephalopathy. It is caused by deficiency of fatty aldehyde dehydrogenase (summary by Lossos et al., 2006). [from OMIM]

PAX2-related disorder is an autosomal dominant disorder associated with renal and eye abnormalities. The disorder was originally referred to as renal coloboma syndrome and characterized by renal hypodysplasia and abnormalities of the optic nerve; with improved access to molecular testing, a wider range of phenotypes has been recognized in association with pathogenic variants in PAX2. Abnormal renal structure or function is noted in 92% of affected individuals and ophthalmologic abnormalities in 77% of affected individuals. Renal abnormalities can be clinically silent in rare individuals. In most individuals, clinically significant renal insufficiency / renal failure is reported. End-stage renal disease requiring renal transplant is not uncommon. Uric acid nephrolithiasis has been reported. Ophthalmologic abnormalities are typically described as optic nerve coloboma or dysplasia. Iris colobomas have not been reported in any individual with PAX2–related disorder. Ophthalmologic abnormalities may significantly impair vision in some individuals, while others have subtle changes only noted after detailed ophthalmologic examination. Additional clinical findings include high-frequency sensorineural hearing loss, soft skin, and ligamentous laxity. PAX2 pathogenic variants have been identified in multiple sporadic and familial cases of nonsyndromic renal disease including renal hypodysplasia and focal segmental glomerulosclerosis. [from GeneReviews]

Spastic paraplegia 11 (SPG11) is characterized by progressive spasticity and weakness of the lower limbs frequently associated with the following: mild intellectual disability with learning difficulties in childhood and/or progressive cognitive decline; peripheral neuropathy; pseudobulbar involvement; and increased reflexes in the upper limbs. Less frequent findings include: cerebellar signs (ataxia, nystagmus, saccadic pursuit); retinal degeneration; pes cavus; scoliosis; and parkinsonism with characteristic brain MRI features that include thinning of the corpus callosum. Onset occurs mainly during infancy or adolescence (range: age 1-31 years) and in rare cases as late as age 60 years. Most affected individuals become wheelchair bound one or two decades after disease onset. [from GeneReviews]

Any retinitis pigmentosa in which the cause of the disease is a mutation in the TTC8 gene. [from MONDO]

Spastic paraplegia 15 (SPG15), typically an early-onset complex hereditary spastic paraplegia, is characterized by progressive spasticity that begins in the lower extremities and is associated with several manifestations resulting from central and peripheral nervous system dysfunction. While onset of spasticity is typically in mid- to late childhood or adolescence (i.e., between ages 5 and 18 years), other manifestations, such as developmental delay or learning disability, may be present earlier, often preceding motor involvement. Individuals with adult onset have also been reported. [from GeneReviews]

Retinitis pigmentosa (RP) is a clinically and genetically heterogeneous group of retinal dystrophies characterized by a progressive degeneration of photoreceptors, eventually resulting in severe visual impairment. For a discussion of genetic heterogeneity of RP, see 268000. [from OMIM]

Short-rib thoracic dysplasia (SRTD) with or without polydactyly refers to a group of autosomal recessive skeletal ciliopathies that are characterized by a constricted thoracic cage, short ribs, shortened tubular bones, and a 'trident' appearance of the acetabular roof. SRTD encompasses Ellis-van Creveld syndrome (EVC) and the disorders previously designated as Jeune syndrome or asphyxiating thoracic dystrophy (ATD), short rib-polydactyly syndrome (SRPS), and Mainzer-Saldino syndrome (MZSDS). Polydactyly is variably present, and there is phenotypic overlap in the various forms of SRTDs, which differ by visceral malformation and metaphyseal appearance. Nonskeletal involvement can include cleft lip/palate as well as anomalies of major organs such as the brain, eye, heart, kidneys, liver, pancreas, intestines, and genitalia. Some forms of SRTD are lethal in the neonatal period due to respiratory insufficiency secondary to a severely restricted thoracic cage, whereas others are compatible with life (summary by Huber and Cormier-Daire, 2012 and Schmidts et al., 2013). There is phenotypic overlap with the cranioectodermal dysplasias (Sensenbrenner syndrome; see CED1, 218330). For a discussion of genetic heterogeneity of short-rib thoracic dysplasia, see SRTD1 (208500). [from OMIM]

Pseudoxanthoma elasticum (PXE) is a systemic disorder that affects the elastic tissue of the skin, the eye, and vascular system. Individuals most commonly present with angioid streaks of the retina found on routine eye examination or associated with retinal hemorrhage and/or characteristic papules in the skin. The most frequent cause of morbidity and disability in PXE is reduced vision due to complications of subretinal neovascularizations and macular atrophy. Other manifestations include premature gastrointestinal angina and/or bleeding, intermittent claudication of arm and leg muscles, stroke, renovascular hypertension, and cardiovascular complications (angina/myocardial infarction). Most affected individuals live a normal life span. [from GeneReviews]

Age-related macular degeneration-4 (ARMD) is a disorder of the eye characterized by the formation of drusen on the retina, often as cuticular drusen which appear in a 'starry sky' distribution on fluorescein angiography. The disorder results in a progressive loss of central vision (summary by Hageman et al., 2005, Grassi et al., 2007). [from OMIM]

Any retinitis pigmentosa in which the cause of the disease is a mutation in the PROM1 gene. [from MONDO]

Bothnia retinal dystrophy is an autosomal recessive disorder with onset of night blindness in childhood. The fundus has a characteristic appearance with yellow-white spots, and at later stages patients develop widespread retinal degeneration with areas of chorioretinal atrophy (summary by Granse et al., 2001). [from OMIM]

Any retinitis pigmentosa in which the cause of the disease is a mutation in the CNGB1 gene. [from MONDO]

Stargardt disease (STGD) is the most common hereditary macular dystrophy and is characterized by decreased central vision, atrophy of the macula and underlying retinal pigment epithelium, and frequent presence of prominent flecks in the posterior pole of the retina. STGD is most commonly inherited as an autosomal recessive trait (see 248200), but STGD4 is inherited as an autosomal dominant trait (summary by Kniazeva et al., 1999). For a general phenotypic description and a discussion of genetic heterogeneity of Stargardt disease, see STGD1 (248200). [from OMIM]

Age-related macular degeneration-2 (ARMD2) is a complex disorder characterized by the accumulation of drusen in and under the retinal pigment epithelium (RPE) and the progressive atrophy of the macular RPE. These changes result in loss of photoreceptor function and vision impairment. Environmental risk factors include cigarette smoking, diet, and cholesterol level (summary by Allikmets et al., 1997). For a general phenotypic description and a discussion of genetic heterogeneity of age-related macular degeneration, see 603075. [from OMIM]