Digits that appear disproportionately short compared to the hand/foot. The word brachydactyly is used here to describe a series distinct patterns of shortened digits (brachydactyly types A-E). This is the sense used here.

A thumb with three phalanges in a single, proximo-distal axis. Thus, this term applies if the thumb has an accessory phalanx, leading to a digit like appearance of the thumb.

Webbing or fusion of the 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 toes in a proximo-distal axis are referred to as "Symphalangism".

Absence of the middle phalanx of the little (5th) finger.

A bilateral form of triphalangeal thumb.

A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve.

A bilateral form of sensorineural hearing impairment.

Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.

An abnormally increased height of the forehead.

An abnormal conical form of the teeth, that is, a tooth whose sides converge or taper together incisally.

Agenesis specifically affecting one of the classes incisor, premolar, or molar.

Hidrotic ectodermal dysplasia 2, or Clouston syndrome (referred to as HED2 throughout this GeneReview) is characterized by a triad of major clinical features including partial-to-complete alopecia, nail dystrophy, and palmoplantar hyperkeratosis. Sweating is preserved and there are usually no dental anomalies. Sparse scalp hair and dysplastic nails are seen early in life. In infancy, scalp hair is fine, sparse, and brittle. Progressive hair loss may lead to total alopecia by puberty. The nails may be milky white in early childhood; they gradually become dystrophic, thick, and distally separated from the nail bed. Palmoplantar keratoderma may develop during childhood and increases in severity with age. Associated features may include cutaneous hyperpigmentation (particularly over the joints) and finger clubbing. The clinical manifestations are highly variable even within the same family.

Onychodystrophy (nail dystrophy) refers to nail changes apart from changes of the color (nail dyschromia) and involves partial or complete disruption of the various keratinous layers of the nail plate.

A nail that is diminished in length and width, i.e., underdeveloped nail.

Congenital absence of the toenail.

Absence of nail of little finger.

Absence of thumb nail.