Netherton syndrome: report of two Taiwanese siblings with staphylococcal scalded skin syndrome and mutation of SPINK5.

Netherton syndrome (NS) is a severe autosomal recessive ichthyosis. It is characterized by congenital ichthyosiform erythroderma, trichorrhexis invaginata, ichthyosis linearis circumflexa, atopic diathesis and frequent bacterial infections. Pathogenic mutations in SPINK5 have recently been identified in NS. SPINK5 encodes lymphoepithelial Kazal-type-related inhibitor (LEKTI), a new type of serine protease inhibitor involved in the regulation of skin barrier formation and immunity. We report two Taiwanese brothers with NS. The patients had typical manifestations of NS with an atopic diathesis and recurrent staphylococcal infections, including staphylococcal scalded skin syndrome (SSSS) since birth. Horny layers were obtained by skin surface biopsy for electron microscopy from lesional skin of both patients and from normal controls. All 33 exons and flanking intron boundaries of SPINK5 were amplified for direct sequencing. The ultrastructure of the stratum corneum (SC) was characterized by premature degradation of corneodesmosomes (CDs) with separation of corneocytes. A homozygous 2260A --> T (K754X) mutation of SPINK5 was found in both patients. Staphylococcal exfoliative toxin A (ETA) is a serine protease capable of cleaving desmoglein 1, an important adhesive molecule of CDs, and can cause separation of the SC, resulting in SSSS. The premature degradation of CDs found in our patients may be attributable to insufficient LEKTI, and possibly also to colonization/infection of ETA-producing Staphylococcus aureus. Mechanisms involved in the pathogenesis of the skin barrier defect in NS are proposed. Further study is needed to prove this hypothesis.