Ectrodactyly–ectodermal dysplasia–cleft syndrome

Ectrodactyly–ectodermal dysplasia–cleft syndrome
Classification and external resources
OMIM	129900
DiseasesDB	34402
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Ectrodactyly–ectodermal dysplasia–cleft syndrome, or EEC, and also referred to as EEC syndrome (also known as "Split hand–split foot–ectodermal dysplasia–cleft syndrome") is a rare form of ectodermal dysplasia, an autosomal dominant disorder inherited as an genetic trait. EEC is characterized by the triad of ectrodactyly, ectodermal dysplasia, and facial clefts. Other features noted in association with EEC include vesicoureteral reflux, recurrent urinary tract infections, obstruction of the nasolacrimal duct, decreased pigmentation of the hair and skin, missing or abnormal teeth, enamel hypoplasia, absent punctae in the lower eyelids, photophobia, occasional cognitive impairment and kidney anomalies, and conductive hearing loss.

Ectrodactyly involves the deficiency or absence of one or more central digits of the hand or foot and is also known as split hand–split foot malformation (SHFM). The hands and feet of people with ectrodactyly are often described as "claw-like" and may include only the thumb and one finger (usually either the little finger, ring finger, or a syndactyly of the two) with similar abnormalities of the feet.

Ectodermal dysplasia describes abnormalities of structures derived from the embryonic ectoderm. These abnormalities affect both the superficial ectodermal layer, as well as the mesectodermal layer constituted by the neural crest.

Ectodermal dysplasia is characterized by absent sweat glands resulting in dry (hypohydrotic), often scale-like skin, sparse and usually coarse scalp hair that is often blonde, sparse eyebrows and eyelashes, and small brittle nails. In addition, abnormalities of ectodermal derivatives, neuroectodermal derivatives, and mesectodermal derivatives are often found. The ectodermal derivative abnormalities can affect the epidermis including mammary, pituitary and sweat glands, as well as hairs, dental enamel, nails, lens, and the internal ear. Neuroectodermal derivatives that can be affected include sensory placodes, cutaneous pigmental cells, and hair buds. Mesectodermal derivatives affected can include the dermis, hypodermis, dentin, head muscles and conjunctival cells, cervicofacial vascular endothelial cells, and part of the maxillofacial skeleton.

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