In addition, characterisation of HI patient skin has shown a loss of nonpolar lipids [26] and abnormal glucosylceramide localization [14], and experiments with patient-derived keratinocytes showed aberrant glucosylceramide accumulation in lamellar granules [27], which is indicative of a lipid transport defect as a result of loss of ABCA12 function [14,26,27]. This evidence concerns the gene ABCA12 and Harlequin ichthyosis.