Human ABCA12 blocking peptide

The corneocyte lipid envelope (CLE), a monolayer of u-hydroxyceramides whose function(s) remain(s) uncertain, is absent in patients with autosomal recessive congenital ichthyoses with mutations in enzymes that regulate epidermal lipid synthesis. Secreted lipids fail to transform into lamellar membranes in certain autosomal recessive congenital ichthyosis epidermis, suggesting the CLE provides a scaffold for the extracellular lamellae. However, because cornified envelopes are attenuated in these autosomal recessive congenital ichthyoses, the CLE may also provide a scaffold for subjacent cornified envelope formation, evidenced by restoration of cornified envelopes after CLE rescue. We provide multiple lines of evidence that the CLE originates as lamellar body-limiting membranes fuse with the plasma membrane: (i) ABCA12 patients and Abca12 e/e mice display normal CLEs; (ii) CLEs are normal in Netherton syndrome, despite destruction of secreted LB contents; (iii) CLEs are absent in VSP33B-negative patients; (iv) limiting membranes of lamellar bodies are defective in lipid-synthetic autosomal recessive congenital ichthyoses; and (v) lipoxygenases, lipase activity, and LIPN co-localize within putative lamellar bodies.

Harlequin ichthyosis (HI) is a rare severe form of congenital ichthyosis, which may be fatal and affects infants before birth, characterized by thickening of the keratin layer in fetal human skin. HI has an incidence of about 1 in 300,000 births. Generally transmitted through autosomal recessive inheritance and is due to mutation in the ABCA12 gene located on chromosome 2(2q34). Prenatal diagnosis remains difficult but may be possible in high risk pregnancies by performing a fetal skin biopsy or by 3D ultrasonography. CASE REPORT: We report a case of HI for its rarity and briefly review the literature. CONCLUSION: This case has been reported for the rarity of HI and to create awareness among paediatricians to identify the condition promptly.