Harlequin-type ichthyosis

Harlequin-type ichthyosis is a genetic disorder that results in thickened skin over nearly the entire body at birth, forming large diamond, trapezoid or rectangle shaped plates separated by deep cracks that affect the eyelids, nose, mouth and ears and limit movement of the arms and legs. Restricted chest movement can cause breathing difficulties, and the plates fall off over several weeks; other complications include premature birth, infection, problems with body temperature and dehydration. It is the most severe form of ichthyosis and is caused by mutations in the ABCA12 gene, which codes for a protein that transports lipids out of cells in the outer layer of skin; the disorder is autosomal recessive. There is no cure, and around half of those affected die within the first few months, though retinoid treatment can increase survival. The condition affects around 1 in 300,000 births and was first documented in a diary entry by Reverend Oliver Hart in America in 1750.