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.

Ulna hypoplasia - intellectual deficit is a very rare syndrome characterized by mesomelic shortness of the forearms, bilateral clubfeet, aplasia or hypoplasia of all nails and severe psychomotor retardation.

Keipert syndrome (KPTS) is characterized by craniofacial and digital abnormalities and variable learning difficulties. The distinctive facial appearance includes broad forehead, hypertelorism, prominent nose, wide mouth, and prominent upper lip with cupid bow configuration. Digital anomalies are also distinctive, with widening of all distal phalanges, particularly of the thumbs and great toes (Amor et al., 2019).

This syndrome has main characteristics of bowing of the femora, aplasia or hypoplasia of the fibulae and poly, oligo and syndactyly. It has been reported in 11 patients. Most of the patients also had a hypoplastic pelvis and hypoplasia of the fingers and fingernails. Some had congenital dislocation of the hip, absence or fusion of tarsal bones, absence of various metatarsals and hypoplasia and aplasia of the toes. The syndrome is caused by a partial loss of WNT7A function (gene mapped to 3p25).

The DDOD syndrome is characterized by autosomal dominant inheritance of congenital deafness and onychodystrophy. Conical, hypoplastic teeth is also a feature (Robinson et al., 1962). See also DOOR syndrome (220500), an autosomal recessive disorder, which includes congenital deafness, onychodystrophy, osteodystrophy, and mental retardation.

Although nails appear normal at birth, dystrophic changes develop within the first decade of life, resulting in onycholysis of fingernails and anonychia of toenails (summary by Rafiq et al., 2004). This disorder is referred to here as nonsyndromic congenital nail disorder-9 (NDNC9). For a list of other nonsyndromic congenital nail disorders and a discussion of genetic heterogeneity, see NDNC1 (161050).

Some ectodermal dysplasias are here classified as congenital disorders characterized by abnormal development in 2 or more ectodermal structures (hair, nails, teeth, and sweat glands) without other systemic findings. Ectodermal dysplasia of the hair/nail type is a rare congenital condition characterized by hypotrichosis and nail dystrophy without nonectodermal or other ectodermal manifestations.

Adams-Oliver syndrome (AOS) is characterized by aplasia cutis congenita (ACC) of the scalp and terminal transverse limb defects (TTLD). ACC lesions usually occur in the midline of the parietal or occipital regions, but can also occur on the abdomen or limbs. At birth, an ACC lesion may already have the appearance of a healed scar. ACC lesions less than 5 cm often involve only the skin and almost always heal over a period of months; larger lesions are more likely to involve the skull and possibly the dura, and are at greater risk for complications, which can include infection, hemorrhage, or thrombosis, and can result in death. The limb defects range from mild (unilateral or bilateral short distal phalanges) to severe (complete absence of all toes or fingers, feet or hands, or more, often resembling an amputation). The lower extremities are almost always more severely affected than the upper extremities. Additional major features frequently include cardiovascular malformations/dysfunction (23%), brain anomalies, and less frequently renal, liver, and eye anomalies.

Zimmermann-Laband syndrome-3 (ZLS3) is characterized by developmental delay, intellectual disability, coarse face, gingival hyperplasia, and nail hypoplasia/aplasia (Bauer et al., 2019). For a general phenotypic description and a discussion of genetic heterogeneity of Zimmermann-Laband syndrome, see ZLS1 (135500).

Hoxha-Aliu syndrome (HXAL) is characterized by mildly impaired intellectual development and digital anomalies of the hands and feet (Hoxha and Aliu, 2023; Guo et al., 2023). Biallelic missense mutations in the ERI1 gene have been reported to cause a more severe bone disorder, spondyloepimetaphyseal dysplasia, Guo-Campeau type (SEMDGC; 620663).

The Guo-Campeau type of spondyloepimetaphyseal dysplasia (SEMDGC) is characterized by severe bone dysplasia resulting in significant short stature with variable anomalies of the spine, pelvis, hips, and extremities, including short, rudimentary, or absent digits. Patients also exhibit variable facial dysmorphisms (Guo et al., 2023). Biallelic null mutations in the ERI1 gene have been reported to cause a less severe disorder, Hoxha-Alia syndrome, involving digital anomalies and mild intellectual disability (HXAL; 620662).