Refinement of a locus for Marie Unna hereditary hypotrichosis to a 1.1-cM interval at 8p21.3.

Summary Background  Marie Unna hereditary hypotrichosis (MUHH) is a rare autosomal congenital alopecia with progressive hair loss starting in early childhood and accelerating at puberty. A locus for MUHH has been mapped on chromosome 8p21 but no genes for MUHH have been identified to date. Objectives  To refine the MUHH locus to a narrow chromosome region to facilitate cloning of the gene. Methods  We performed genotyping and linkage analysis in a multigeneration Chinese family with MUHH, using 18 high-density microsatellite markers spanning the previously mapped interval at 8p21. Results  Significant evidence for linkage was observed in this region, with a maximum two-point LOD score of 3·01 (θ = 0). Haplotype analysis localized the MUHH locus within the region defined by D8S282 and D8S1839. This region overlaps by 1·1-cM with the previously reported MUHH region and represents a physical distance of about 380 kb. Conclusions  This study provides a refined map location (1·1 cM) for isolation of the gene causing MUHH. These data also indicate the existence of a common MUHH locus at 8p21.3 between affected caucasian and Chinese families.