Abstract： Objective To confirm the diagnosis and to localize the pathogenic gene of ectodermal dysplasia in a family SUffering from only hair and nail abnormalities.MethodsBlood samples were collected from 7 affected patients and 15 unafiected individuals in the family.Genomic DNA was extracted from blood samples by routine phenol-chloroform methods.The whole coding regions of candidate genes K16,K17,K6a,K6b and GJB6 were amplified by PCR followed by direct sequencing.Then,the gene mutation was further confirmed at mRNA level by RT-PCR.ResultsA heterozygous missense mutation 3 1G→A in the GJB6 gene.which leads to the substitution of glycine by arginine at codon 11(G11R)on the N-terminal of the protein,was detected in all the patients.but in none of the 15 normal individuals in this family.The mutation was also confirmed in the CDNA originating from the proband's skin biopsy.Conelusionn A missense mutation G31A.which has been shown previously to cause hidrotic ectodermal dysplasia(HED),is localized in the GJB6 gene of patients in this family.