Novel hairless mutations in two kindreds with autosomal recessive papular atrichia

Papular atrichia is an autosomal recessive disorder characterized clinicall y by the occurrence of universal congenital alopecia and disseminated papul ar lesions. Recently, mutations in the human hairless (HR) gene have been r eported in Irish and Arab Palestinian families with papular atrichia. We ha ve studied two further kindreds with this clinical phenotype from other eth nic backgrounds. For mutation detection the complete coding region as well as exon-intron boundaries of the HR gene were sequenced. The first family i s a Mexican family with clinically typical papular atrichia, Sequencing ide ntified a homozygous deletion of 4 bp in exon 7 (2001delCCAG) leading to a premature stop codon in exon 8. The second family is a South Tyrolian famil y with affected individuals showing papular atrichia and retardation of bon e age during childhood. All affected individuals were identified as homozyg ous for an A-->G transition at nucleotide position 2909 (exon 14) leading t o an amino acid change of asparagine to serine in codon 970 (Asn970Ser). Th ese data provide further evidence for the involvement of hairless mutations in papular atrichia. In addition, these findings suggest that the hairless protein is not only involved in hair development but also in the process o f ossification during development.