Ectrodactyly, sometimes referred to as “Lobster-Claw Syndrome”, involves the deficiency or absence of one or more central digits of the hand or foot.

A large number of human gene defects can cause ectrodactyly, such as from deletions, translocations, and inversions in chromosome 7 (7q). These alterations in 7q can have a strong connection with growth impairment, microcephaly (abnormal smallness of the head and brain), deformities of the facial bones, hernias, hearing loss, and mental retardation. Ectrodactyly can be inherited from a parent, but many individuals are the first in their family to be affected.

Ectrodactyly is frequently seen with other congenital anomalies, or other birth defects, and may be caused by genetic factors or by exposure of the embryo to environmental factors. When two or more genes are affected by a chromosomal rearrangement, other disorders associated are with ectrodactyly, including cleft lip and/or cleft palate (Electrodactyly-Ectodermal dysplasia-Clef Syndrome, or EEC). Other abnormalities include absence of the teeth and other dental abnormalities, decreased ability to sweat, absence of tear ducts, photophobia (increased sensitivity to light), and kidney abnormalities. Most individuals with ectrodactyly have some of these abnormalities, but very few individuals have all of these abnormalities.

The cosmetic concerns of the syndrome can have a tremendous impact on the quality of life of an individual with ectrodactyly. The facial and limb differences can be socially isolating and physically challenging as many individuals erroneously assume that people with EEC syndrome have limited abilities. The overall incidence of ectodermal dysplasias in the United States is seven out of 10,000 people and the prognosis for most people with ectrodactyly is very good. In general, they have minimal and manageable serious medical problems, normal IQ, and most achieve success and have a long life, irregardless of their disabilities. The life expectancy of individuals with EEC syndrome without sweating problems is expected to be normal. EEC syndrome is usually diagnosed through a combination of clinical exam, x rays, kidney imaging tests, skin biopsy, and DNA testing.

No cure exists for EEC syndrome, but there are many treatments available to address the symptoms. These treatments include surgery, dental care, prevention of complications from hypohydrosis (abnormal sweating), and other preventative treatments. Surgery may be needed to correct cleft lips and cleft palates and is important for feeding and for speech. Podiatric physicians may perform surgery on foot abnormalities to improve the function of the lower limbs, to improve the appearance of the limbs, and to aid in shoe fit.

In 2006, the London Tate exhibition Single Shot featured a video of an unidentified person with ectrodactyly skillfully playing the piano with only four fingers: Hyewon Kwon -- Bittersweet.