Malady of the Month Archives Few congenital birth defects are as disturbing to the eyes (and souls) of its witnesses than Harlequin Ichthyosis - commonly known as Harlequin Fetus. In this rare genetic disorder, which occurs in 1 in 300,000 births, babies are born with a massive horny shell of dense platelike scales and contraction abnormalities of the eyes, ears, mouth and appendages. Basically, wherever a fold would normally occur in a newborn baby, these poor souls have cracks.