Waardenburg syndrome type 3 is an auditory-pigmentary syndrome characterized by pigmentary abnormalities of the hair, skin, and eyes; congenital sensorineural hearing loss; presence of 'dystopia canthorum,' the lateral displacement of the ocular inner canthi; and upper limb abnormalities (reviews by Read and Newton, 1997 and Pingault et al., 2010). WS type 3 is also referred to as 'Klein-Waardenburg syndrome' (Gorlin et al., 1976). Clinical Variability of Waardenburg Syndrome Types 1-4 Waardenburg syndrome has been classified into 4 main phenotypes. Type I Waardenburg syndrome (WS1; 193500) is characterized by pigmentary abnormalities of the hair, including a white forelock and premature graying; pigmentary changes of the iris, such as heterochromia iridis and brilliant blue eyes; congenital sensorineural hearing loss; and 'dystopia canthorum.' WS type II (WS2) is distinguished from type I by the absence of dystopia canthorum. WS type III has dystopia canthorum and is distinguished by the presence of upper limb abnormalities. WS type IV (WS4; 277580), also known as Waardenburg-Shah syndrome, has the additional feature of Hirschsprung disease (reviews by Read and Newton, 1997 and Pingault et al., 2010).

Craniofrontonasal syndrome is an X-linked developmental disorder that shows paradoxically greater severity in heterozygous females than in hemizygous males. Females have frontonasal dysplasia, craniofacial asymmetry, craniosynostosis, bifid nasal tip, grooved nails, wiry hair, and abnormalities of the thoracic skeleton, whereas males typically show only hypertelorism (Twigg et al., 2004; Wieland et al., 2004).

Multiple pterygium syndromes comprise a group of multiple congenital anomaly disorders characterized by webbing (pterygia) of the neck, elbows, and/or knees and joint contractures (arthrogryposis) (Morgan et al., 2006). The multiple pterygium syndromes are phenotypically and genetically heterogeneous but are traditionally divided into prenatally lethal (253290) and nonlethal (Escobar) types.

Bartsocas-Papas syndrome-1 (BPS1) is an autosomal recessive disorder characterized by multiple popliteal pterygia, ankyloblepharon, filiform bands between the jaws, cleft lip and palate, and syndactyly. Early lethality is common, although survival into childhood and beyond has been reported (summary by Mitchell et al., 2012). Genetic Heterogeneity of Bartsocas-Papas Syndrome Bartsocas-Papas syndrome-2 (BPS2) is caused by mutation in the CHUK gene (600664). A less severe form of popliteal pterygium syndrome (PPS; 119500) is caused by mutation in the IRF6 gene (607199).

Omodysplasia-1 (OMOD1) is a rare autosomal recessive skeletal dysplasia characterized by severe congenital micromelia with shortening and distal tapering of the humeri and femora to give a club-like appearance. Typical facial features include a prominent forehead, frontal bossing, short nose with a depressed broad bridge, short columella, anteverted nostrils, long philtrum, and small chin. Variable findings are cryptorchidism, hernias, congenital heart defects, and cognitive delay (Elcioglu et al., 2004; Albano et al., 2007). Genetic Heterogeneity of Omodysplasia Also see omodysplasia-2 (OMOD2; 164745), an autosomal dominant form of the disorder in which abnormalities are limited to the upper limbs. The facial changes and typical growth defect of the distal humerus with complex deformity of the elbows appear to be similar in both entities (Baxova et al., 1994).

Lethal congenital contracture syndrome-9 (LCCS9) is an autosomal recessive disorder characterized by multiple flexion and extension contractures resulting from reduced or absent fetal movement (Ravenscroft et al., 2015). For a general phenotypic description and discussion of genetic heterogeneity of lethal congenital contracture syndrome, see LCCS1 (253310).

Bartsocas-Papas syndrome-2 (BPS2) is a severe form of popliteal pterygium disorder characterized by cutaneous webbing across one or more joints, cleft lip and/or palate, syndactyly, and genital malformations (summary by Leslie et al., 2015).

Epidermolysis bullosa with pyloric atresia (EB-PA) is characterized by fragility of the skin and mucous membranes, manifested by blistering with little or no trauma; congenital pyloric atresia; and ureteral and renal anomalies (dysplastic/multicystic kidney, hydronephrosis/hydroureter, ureterocele, duplicated renal collecting system, absent bladder). The course of EB-PA is usually severe and often lethal in the neonatal period. Most affected children succumb as neonates; those who survive may have severe blistering with formation of granulation tissue on the skin around the mouth, nose, fingers, and toes, and internally around the trachea. However, some affected individuals have little or no blistering later in life. Additional features shared by EB-PA and the other major forms of EB include congenital localized absence of skin (aplasia cutis congenita) affecting the extremities and/or head, milia, nail dystrophy, scarring alopecia, hypotrichosis, contractures, and dilated cardiomyopathy.

Autosomal dominant intellectual developmental disorder-73 (MRD73) is a highly variable neurodevelopmental disorder characterized by impaired intellectual development that ranges from mild to severe, speech delay, behavioral abnormalities, and nonspecific dysmorphic facial features (Janssen et al., 2022).