Ichthyosis Vulgaris Pathogenic Gene Mapping Studies

Wei Zhong (Microbiology) Directed by Guoping Zhao, Xiangyin KongIchthyosis vulgaris (IV) is the common form of inherited scaling skin disorder, with prevalence estimated at 1 in 250-5300. In Chinese population, the prevalence is about 2.29 ‰. The onset of IV is usually within one year after birth. The patients manifest with white scaling on the extensor surfaces of the extremities and occasionally the trunk. Clinical features also include hyperlinearity of the palms and soles, atopy and heat intolerance or keratosis pilaris. Genetically, IV is thought to be an autosomal dominant disorder with virtually complete penetrance. Due to the difficulties in collecting suitable large affected families, linkage studies to map the gene involved in IV are rarely done. Although evidence revealed the crucial importance of filaggrin (FLG) and the epidermal differentiation complex(EDC) in normal epidermal function and the molecular basis of IV, no mutation of FLG has been found in IV patient and the gene responsible for this disorder has not been elucidated. To find the disease gene, we collected two affected Chinese IV families with highly similar histological features for linkage analysis. Linkage analysis identified an IV locus on chromosome 1q22 with a maximum two-point lod score of 2.47 at D1S1653 (θ=. 00). Haplotype analysis placed the critical region to a 7cM interval defined by D1S1653 and D1S2675. These results provide the basis for further identifying the gene responsible for IV disorder.