White Sponge Nevus 1

A number sign (#) is used with this entry because of evidence that white sponge nevus-1 (WSN1) is caused by heterozygous mutation in the keratin-4 gene (KRT4; 123940) on chromosome 12q13.

Description

White sponge nevus is a rare autosomal dominant disorder of noncornifying squamous epithelial differentiation that presents clinically as white, soft, thick plaques of the oral mucosa. Less frequently, the mucous membranes of the nose, esophagus, genitalia, and rectum are involved. Histopathologic features, including epithelial thickening, parakeratosis, extensive vacuolization of the suprabasal keratinocytes, and compact aggregates of keratin intermediate filaments in the upper spinus layers resemble those found in epidermal disorders shown to be associated with keratin defects (summary by Richard et al., 1995).

Genetic Heterogeneity of White Sponge Nevus

White sponge nevus-2 (WSN2; 615785) is caused by mutation in the KRT13 gene (148065) on chromosome 17q21.

Clinical Features

White sponge nevus is manifested by thickened spongy-fold mucosa with a white opalescent tint in the mouth. The vagina, rectum, and nasal cavity may be similarly involved. It is differentiated from benign intraepithelial dyskeratosis (127600) by the presence of vaginal and anal lesions and the absence of conjunctival involvement and the characteristic cell-within-cell histologic change. Scott (1966) found 3 generations affected. Verma (1967) described the disorder in Asiatic Indians. Ultrastructural studies were carried out by Whitten (1970) and McGinnis and Turner (1975). Jorgenson and Levin (1981) pointed out that there are no extramucosal lesions associated with WSN and that the plaques of WSN undergo alternate periods of remission and exacerbation. In 2 members of a family penicillin was thought to have led to remission.

Inheritance

Haye and Whitehead (1968) reported on 7 cases in 3 generations with male-to-male transmission, supporting autosomal dominant inheritance.

Molecular Genetics

In affected members of 2 Scottish kindreds with white sponge nevus, Rugg et al. (1995, 1995) found heterozygosity for a 3-bp deletion in the 1A domain of the KRT4 gene (123940.0001).

In 3 affected members of an Italian family with white sponge nevus, Terrinoni et al. (2000) identified a heterozygous 3-bp insertion in the 1A domain of the KRT4 gene (123940.0002). The phenotype of the proband was considered mild, as only part of the buccal and labial mucosa were involved.