Harlequin ichthyosis unmasked: a defect of lipid transport.

Harlequin ichthyosis (HI)--the most severe form of keratinizing disorders, often lethal in the neonatal period--is characterized by a profound thickening of the keratin skin layer, a dense "armor"-like scale that covers the body, and contraction abnormalities of the eyes, ears, and mouth. In this issue of the JCI, Akiyama et al. report that mutations in ABCA12 caused defective lipid transport that significantly impacted normal development of the skin barrier. Lipid secretion was recovered after corrective ABCA12 gene transfer into patient keratinocytes. These results should allow for early prenatal diagnosis of HI and lend hope to the possibility of a specific treatment for this devastating disorder.