Autosomal Recessive Pure Hair and Nail Ectodermal Dysplasia Linked to Chromosome 12p11.1-q14.3 Without KRTHB5 Gene Mutation

The study focused on a large consanguineous Pakistani family with four siblings affected by a congenital autosomal recessive form of hair-nail ectodermal dysplasia (HNED). Linkage analysis using chromosome 12 markers revealed a lod score of 2.92 at locus D12S368, suggesting the disease gene was located on chromosome 12. Despite sequencing candidate genes, including KRTHB5 and four other keratin II genes, no mutations were found in the coding regions of KRTHB5. The findings indicated that the family might have a non-coding mutation in KRTHB5 or a mutation in an unknown gene within the linked region on chromosome 12.