Investigation of hHB genes in a predigree of congenital monilethrix

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 O 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.

一汉族念珠状发家系调查和Ⅱ型毛发角蛋白基因突变分析

目的分析一汉族念珠状发家系成员Ⅱ型毛发角蛋白(hHb)基因的突变情况。方法收集1个汉族念珠状发家系的临床资料,应用皮肤镜检查家系成员的毛发,再以光镜、扫描电镜明确病发特征。采集患儿及其家系成员和100例健康对照的血样,提取DNA,PCR扩增hHb1、hHb3、hHb6基因外显子1和7,测序后对结果进行比对分析。结果先证者女,8岁,自出生后2个月开始部分头发变得脆弱易断,容易拔出。皮肤科检查:头发弥漫性稀疏,多数为2 cm长的断发,外观异常,肉眼可见全头散在串珠状发,以后枕部为多,颈后部见毛囊角化性丘疹。诊断:念珠状发。调查该家系3代共15人,发现4例念珠状发患者,皮肤镜下患者的毛干呈典型的串珠状结构。连续外搽2%米诺地尔溶液9个月后先证者毛发较前明显变长变密。4例患者hHb6基因第7外显子均检测到1个杂合突变c.1237G>A(p.E413K),而家系中健康成员及100例健康对照未检测到突变。结论首次在中国一个汉族念珠状发家系患者中检测到hHb6基因E413K突变,该突变可能是导致念珠状发的原因。