Bathing Suit Variant of Autosomal Recessive Congenital Ichthyosis (ARCI) in Two Indian Patients

Abstract

Bathing suit ichthyosis (BSI) is a rare variant of autosomal recessive congenital ichthyosis (ARCI) due to transglutaminase-1 gene (TGM1) mutations leading to a temperature sensitive phenotype. It is characterized by dark-grey or brownish scaling restricted to the "bathing suit" areas. We report two Indian girls with bathing suit ichthyosis and mutations in TGM1 (patient 1: homozygous for c.1147G>A; patient 2: compound heterozygous for c.832G>A, c.919C>G).

Figure 1

Clinical presentation of patient 1 and 2. (a, c). Patient 1 shows a lamellar type of ichthyosis involving the forehead, external auditory meatus, and neck, but sparing the centrofacial area by additional involvement of the bathing suit area. (b, d) Patient 2 shows a mild ichthyosis confined to bathing suit area with involvement of the axilla, but sparing of ears and face. The patient has been seen in winter.

Figure 2

Histopathology of the ichthyotic area in patient 2 shows hyperkeratosis with follicular plugging and hyperplasia of the epidermis with well-preserved stratum granulosum. (HE: haematoxylin & eosin; SG: stratum granulosum; scale bare = 100 μm).

Figure 3

Localization of mutations within transglutaminase 1 causing bathing suit ichthyosis. (a) Results of sanger sequencing of patient 1 and 2 to confirm mutations described here. (b) The localization of the 2006 by Oji et al. published mutations p.Arg315Cys/His, p.Arg126Cys, p.Arg389Pro, p.Arg264Trp/Gln, p.Tyr276Asn, p.Arg687His, p.Arg307Gly (Oji, V. et al. 2006), and the two mutations p.Val383Met and p.Gly278Arg found in two Indian children is depicted within a three-dimensional model of transglutaminase 1. The well-known mutation p.Arg307Gly was also found in the two Indian children. Three-dimensional modeling of transglutaminase 1 isoform 1 was performed by using the online in-silico protein structure prediction tool SWISS MODEL (Swiss institute of Bioinformatics, SIB). For structural alignment the structure of transglutaminase 3 was used as template. (b) Results of sanger sequencing of patient 1 and 2 to confirm mutations described here.