<正>Objective: To investigate the gene polymorphism in a pedigree of congenital monilethrix. Methods: Genomic DNA of affected members

the normal members of the pedigree and 50 unrelated normal members who came from different regions were extracted with a whole blood genomic DNA extraction kit and used as a template for the polymerase chain reaction （PCR）-mediated amplification of hHB1 and hHB6 genes. Results: In the pedigree

DNA analysis of patients and normal persons revealed C（447th） in exonl of hHB1 gene and the 52th codon was CCA encoding arginine. But it was a heteropeak of G or C in 50 unrelated normal members

which encodes glycine or arginine. It showed that this change was a single nucleotide polymorphisms （SNP）. Conclusion:A genetic heterogeneity of monilethrix exists in Chinese population. SNP which can result in the change of amino acid sequence is found in a pedigree of congenital monilethrix

and a genetic heterogeneity of monilethrix existed in Chinese population.