Webbing or fusion of the fingers or toes, involving soft parts only or including bone structure. Bony fusions are referred to as "bony" syndactyly if the fusion occurs in a radio-ulnar axis. Fusions of bones of the fingers or toes in a proximo-distal axis are referred to as "symphalangism".

A widely spaced gap between the first toe (the great toe) and the second toe.

Clinodactyly refers to a bending or curvature of the fifth finger in the radial direction (i.e., towards the 4th finger).

Fusion of the hands and feet by a thin membrane of skin (scarring) seen in forms of dystrophic epidermolysis bullosa and leading to a "mitten" hand deformity.

A reduction in diameter of the distal phalanx of finger towards the distal end.

An overall widening of the spaces between the digits.

A tooth present at birth or erupting within the first month of life.

The loss of intercellular connections, such as desmosomes, resulting in loss of cohesion between keratinocytes.

Loss of all scalp hair.

Alopecia areata is a common disorder that causes hair loss. "Alopecia" is a Latin term that means baldness, and "areata" refers to the patchy nature of the hair loss that is typically seen with this condition.\n\nIn most people with alopecia areata, hair falls out in small, round patches, leaving coin-sized areas of bare skin. This patchy hair loss occurs most often on the scalp but can affect other parts of the body as well. Uncommonly, the hair loss involves the entire scalp (in which case the condition is known as alopecia totalis) or the whole body (alopecia universalis). Other rare forms of alopecia areata, which have different patterns of hair loss, have also been reported.\n\nAlopecia areata affects people of all ages, although it most commonly appears in adolescence or early adulthood. Hair loss occurs over a period of weeks. The hair usually grows back after several months, although it may fall out again. In some cases, unpredictable cycles of hair loss followed by regrowth can last for years. In addition to hair loss, some affected individuals have fingernail and toenail abnormalities, such as pits on the surface of the nails.\n\nThe hair loss associated with alopecia areata is not painful or disabling. However, it causes changes in a person's appearance that can profoundly affect quality of life and self-esteem. In some people, the condition can lead to depression, anxiety, and other emotional or psychological issues.

Congenital anonychia is defined as the absence of fingernails and toenails. Anonychia and its milder phenotypic variant, hyponychia, usually occur as a feature of genetic syndromes, in association with significant skeletal and limb anomalies. Isolated nonsyndromic congenital anonychia/hyponychia is a rare entity that usually follows autosomal recessive inheritance with variable expression, even within a given family. The nail phenotypes observed range from no nail field to a nail field of reduced size with an absent or rudimentary nail (summary by Bruchle et al., 2008). This form of nail disorder is referred to here as nonsyndromic congenital nail disorder-4 (NDNC4). For a list of other nonsyndromic congenital nail disorders and a discussion of genetic heterogeneity, see NDNC1 (161050).

Aplasia cutis congenita (ACC) is defined as congenital localized absence of skin. The skin appears as a thin, transparent membrane through which the underlying structures are visible. The location is usually on the scalp (Evers et al., 1995). Approximately 20 to 30% of cases have underlying osseous involvement (Elliott and Teebi, 1997). Autosomal dominant inheritance is most common, but recessive inheritance has also been reported. Cutaneous aplasia of the scalp vertex also occurs in Johanson-Blizzard syndrome (243800) and Adams-Oliver syndrome (AOS; 100300). A defect in the scalp is sometimes found in cases of trisomy 13 and in about 15% of cases of deletion of the short arm of chromosome 4, the Wolf-Hirschhorn syndrome (WHS; 194190) (Hirschhorn et al., 1965; Fryns et al., 1973). Evers et al. (1995) provided a list of disorders associated with aplasia cutis congenita, classified according to etiology. They also tabulated points of particular significance in history taking and examination of patients with ACC.

Absence of a fingernail.

The presence of one or more bullae on the skin, defined as fluid-filled blisters more than 5 mm in diameter with thin walls.

A discontinuity of the skin exhibiting incomplete loss of the epidermis, a lesion that is moist, circumscribed, and usually depressed.