Malformations and anomalies

Skin

There are several forms of ichthyosis (flaky and scaly skin). The most frequent form is inherited in an autosomal dominant manner and is characterized by excessive cornification (hyperkeratosis) that causes the skin to look scaly.
In congenital ectodermal dysplasia, the scalp hair is sparse, the eyebrows are missing, the nails are underdeveloped, and both the palmar and plantar surfaces are hyperkeratinized.

Mammary glands

When the mammary crest fails to degenerate outwith the region of the mammary gland, additional nipples may result. This particularly occurs in the axilla. This condition is termed polythelia. Polymastia is the presence of an additional complete mammary gland.

Teeth

Teeth frequently vary in number, form, size and position. They may be totally or partially absent (anodontia) or may be supernumerary (polyodontia). Defects of the enamel may be due to prenatal or postnatal diseases (tetracycline, high doses of fluoride).