Khadim Shah1,2, Muhammad Ansar1, Zaib-Un-Nisa Mughal1, Falak Sher Khan1, Wasim Ahmad1, Tracey M Ferrara2,3, Richard A Spritz2,3. 1. Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan. 2. Human Medical Genetics and Genomics Program, University of Colorado School of Medicine, Aurora, Colorado, USA. 3. Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA.
Abstract
BACKGROUND: Progressive symmetric erythrokeratoderma (PSEK) is a rare skin disorder characterised by symmetrically distributed demarcated hyperkeratotic plaques, often with associated palmoplantar hyperkeratosis, with new plaques appearing over time. Most cases are inherited in an autosomal dominant manner, although a few cases exhibit apparent autosomal recessive inheritance. OBJECTIVE: To identify the gene underlying autosomal recessive PSEK in a large Pakistani kindred. METHODS: We first carried out autozygosity mapping using microsatellite markers in candidate regions of the genome. We then carried out exome sequencing of five family members, autozygosity mapping and mutation analysis using the exome data and verification by Sanger sequencing. RESULTS: Autozygosity mapping and exome sequencing identified a homozygous frameshift deletion (c.811delA; p.Ser271fs) in KRT83, which co-segregated with the PSEK phenotype in the family and which is expected to abolish keratin 83, a type II keratin of hair and skin. CONCLUSIONS: At least some cases of PSEK result from loss-of-function mutations in KRT83. Heterozygous missense substitutions in KRT83 have been implicated in autosomal dominant monilethrix, a rare hair disorder. Our findings indicate that at least some cases of autosomal recessive PSEK and autosomal dominant monilethrix are allelic, respectively resulting from loss-of-function and missense mutations in the KRT83 gene. Together, these findings indicate that different types of mutations in KRT83 can result in quite different skin and hair phenotypes. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.
BACKGROUND: Progressive symmetric erythrokeratoderma (PSEK) is a rare skin disorder characterised by symmetrically distributed demarcated hyperkeratotic plaques, often with associated palmoplantar hyperkeratosis, with new plaques appearing over time. Most cases are inherited in an autosomal dominant manner, although a few cases exhibit apparent autosomal recessive inheritance. OBJECTIVE: To identify the gene underlying autosomal recessive PSEK in a large Pakistani kindred. METHODS: We first carried out autozygosity mapping using microsatellite markers in candidate regions of the genome. We then carried out exome sequencing of five family members, autozygosity mapping and mutation analysis using the exome data and verification by Sanger sequencing. RESULTS: Autozygosity mapping and exome sequencing identified a homozygous frameshift deletion (c.811delA; p.Ser271fs) in KRT83, which co-segregated with the PSEK phenotype in the family and which is expected to abolish keratin 83, a type II keratin of hair and skin. CONCLUSIONS: At least some cases of PSEK result from loss-of-function mutations in KRT83. Heterozygous missense substitutions in KRT83 have been implicated in autosomal dominant monilethrix, a rare hair disorder. Our findings indicate that at least some cases of autosomal recessive PSEK and autosomal dominant monilethrix are allelic, respectively resulting from loss-of-function and missense mutations in the KRT83 gene. Together, these findings indicate that different types of mutations in KRT83 can result in quite different skin and hair phenotypes. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.