Clinical and pathologic correlations in genetically distinct forms of atrichia

Background: The genetic basis of 2 distinct forms of atrichiawithpapuleshasrecentlybeendefinedatthemolecular level. In atrichia with papular lesions (APL; OnlineMendelianInheritanceinMan[OMIM]209500),mutations in the hairless gene on chromosome 8p21 have recently been identified. Atrichia with papules also occurs in the clinical setting of vitamin D–dependent rickets type IIA (VDDR IIA; OMIM 277440), resulting from mutations in the vitamin D receptor gene on chromosome 12q12-q14. Despite the distinct genetic basis for both forms of atrichia, the clinical findings are strikingly similar and exhibit classic pathognomonic features unique to this phenotype. We sought to document theclinicalandmolecularfeaturesofAPLandVDDRIIA. Observations: Molecular analysis of the hairless and vitaminDreceptorgeneswasperformedongenomicDNA from probands and family members from 3 families with APLand2withVDDRIIA.Wepresentaclinicalandhistologic comparison of atrichia in patients with APL and VDDR IIA and highlight the genetically heterogeneous basis of atrichia by identification of pathogenetic mutations.