Thrombocytopenia absent radius (TAR) syndrome is characterized by bilateral absence of the radii with the presence of both thumbs, and thrombocytopenia that is generally transient. Thrombocytopenia may be congenital or may develop within the first few weeks to months of life; in general, thrombocytopenic episodes decrease with age. Cow's milk allergy is common and can be associated with exacerbation of thrombocytopenia. Other anomalies of the skeleton (upper and lower limbs, ribs, and vertebrae), heart, and genitourinary system (renal anomalies and agenesis of uterus, cervix, and upper part of the vagina) can occur.

Pallister-Killian syndrome (PKS) is a dysmorphic condition involving most organ systems, but is also characterized by a tissue-limited mosaicism; most fibroblasts have 47 chromosomes with an extra small metacentric chromosome, whereas the karyotype of lymphocytes is normal. The extra metacentric chromosome is an isochromosome for part of the short arm of chromosome 12: i(12)(p10) (Peltomaki et al., 1987; Warburton et al., 1987).

SRXY11 is characterized by a genital phenotype that may range from predominantly female to predominantly male, including marked sex ambiguity depending on the duration of normal testicular function prior to the loss of testicular tissue. Approximately half of patients present with micropenis and bilateral cryptorchidism, and half present with female-appearing or ambiguous external genitalia (da Silva et al., 2019; McElreavey et al., 2020). The testicular regression syndrome (TRS) was delineated by Sarto and Opitz (1973), who called it the XY gonadal dysgenesis syndrome. It is characterized primarily by the absence of gonads in an XY person. In most cases, uterus and fallopian tubes are absent but small tubular structures interpreted as mullerian or wolffian rudiments (or both) are present. The range of virilizing effects due to early testicular tissue extends from none in phenotypic females with only slightly hypoplastic normal external genitalia, well-formed but hypoplastic uterus, and well-formed tubes (De Marchi et al., 1981) to the anorchic phenotypic male (Edman et al., 1977). Most affected individuals lack a vagina but a urogenital sinus or pseudovaginal urethral outpouching is found. Partial labioscrotal fusion and clitoris enlargement are common, breast development is absent, and postpubertal eunuchoid habitus is the rule. Sometimes nongenital anomalies are present (summary by Rosenberg et al., 1984).

HDR syndrome (HDRS), also known as Barakat syndrome, is a heterogeneous disorder characterized by the triad of Hypoparathyroidism (H), nerve Deafness (D) and/or Renal disease (R). Variable clinical features include hypogonadotrophic hypogonadism, polycystic ovaries, congenital heart disease, retinitis pigmentosa, and cognitive disability (Barakat et al., 2018).

The Al-Awadi/Raas-Rothschild/Schinzel phocomelia syndrome (AARRS) is a rare autosomal recessive disorder characterized by severe malformations of upper and lower limbs with severely hypoplastic pelvis and abnormal genitalia. The disorder is believed to represent a defect of dorsoventral patterning and outgrowth of limbs (summary by Kantaputra et al., 2010).

Spondylocostal dysostosis-anal and genitourinary malformations syndrome is characterized by the association of spondylocostal dysostosis with anal and genitourinary malformations (anal atresia and agenesis of external and internal genitalia). To date, only four cases have been described in the literature. Autosomal recessive inheritance has been suggested.

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).

Müllerian aplasia and hyperandrogenism is a condition that affects the reproductive system in females. This condition is caused by abnormal development of the Müllerian ducts, which are structures in the embryo that develop into the uterus, fallopian tubes, cervix, and the upper part of the vagina. Individuals with Müllerian aplasia and hyperandrogenism typically have an underdeveloped or absent uterus and may also have abnormalities of other reproductive organs. Women with this condition have normal female external genitalia, and they develop breasts and pubic hair normally at puberty; however, they do not begin menstruation by age 16 (primary amenorrhea) and will likely never have a menstrual period. Affected women are unable to have children (infertile).\n\nWomen with Müllerian aplasia and hyperandrogenism have higher-than-normal levels of male sex hormones called androgens in their blood (hyperandrogenism), which can cause acne and excessive facial hair (facial hirsutism). Kidney abnormalities may be present in some affected individuals.

The 17q12 recurrent deletion syndrome is characterized by variable combinations of the three following findings: structural or functional abnormalities of the kidney and urinary tract, maturity-onset diabetes of the young type 5 (MODY5), and neurodevelopmental or neuropsychiatric disorders (e.g., developmental delay, intellectual disability, autism spectrum disorder, schizophrenia, anxiety, and bipolar disorder). Using a method of data analysis that avoids ascertainment bias, the authors determined that multicystic kidneys and other structural and functional kidney anomalies occur in 85% to 90% of affected individuals, MODY5 in approximately 40%, and some degree of developmental delay or learning disability in approximately 50%. MODY5 is most often diagnosed before age 25 years (range: age 10-50 years).

Coffin-Siris syndrome (CSS) is classically characterized by aplasia or hypoplasia of the distal phalanx or nail of the fifth and additional digits, developmental or cognitive delay of varying degree, distinctive facial features, hypotonia, hirsutism/hypertrichosis, and sparse scalp hair. Congenital anomalies can include malformations of the cardiac, gastrointestinal, genitourinary, and/or central nervous systems. Other findings commonly include feeding difficulties, slow growth, ophthalmologic abnormalities, and hearing impairment.

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA.

Cardiac-urogenital syndrome is characterized by partial anomalous pulmonary venous return in association with tracheal anomalies, pulmonary hypoplasia, congenital diaphragmatic hernia, thyroid fibrosis, thymic involution, cleft spleen, penoscrotal hypospadias, and cryptorchidism (Pinz et al., 2018).

Mayer-Rokitansky-Kuster-Hauser syndrome (MRKH) is characterized by uterovaginal atresia in an otherwise phenotypically normal female with a normal 46,XX karyotype. Anomalies of the genital tract range from upper vaginal atresia to total mullerian agenesis with urinary tract abnormalities. It has an incidence of approximately 1 in 5,000 newborn girls (Cheroki et al., 2006). The abnormality of sexual development in MRKH syndrome is the same as that in the MURCS association (601076), in which cervicothoracic somite anomalies, unilateral renal agenesis, and conductive deafness are also seen. Mullerian aplasia and hyperandrogenism (158330) is caused by mutation in the WNT4 gene (603490). Familial cases of unilateral or bilateral renal agenesis in combination with mullerian anomalies have also been reported (see urogenital adysplasia, 191830).

Meckel syndrome-14 (MKS14) is a lethal disorder characterized by occipital encephalocele, postaxial polydactyly of the hands and feet, and polycystic kidneys. Stillbirth has been reported, as well as death within hours in a live-born affected individual (Shaheen et al., 2016; Ridnoi et al., 2019). For a general phenotypic description and discussion of genetic heterogeneity of Meckel syndrome, see MKS1 (249000).