中文摘要：

目的 对同患念珠状发的母女俩患者进行分子遗传学分析，确定其致病原因。方法调查患者家系系谱，取患者和正常对照的头发进行常规的显微观察，获取临床信息。抽提所有参与实验的家系成员的全基因组DNA。PCR扩增人类毛发碱性角蛋白6基因（human hair basic keratin 6 gene，hHB6）的所有外显子和外显子一内含子交界区。采用直接测序法检测突变。用限制性片段长度多态性分析验证突变和在该家系内突变是否与疾病共分离，以及该突变是否在正常人群中存在。结果在其中一个患者中检测到了hHB6基因的一个杂合突变c．1204G〉h（p．E402K）。限制性片段长度多态性分析确证了母女俩患者均携带该突变，而家系中其他人（表型均正常）和150名不相关的正常中国汉族人不携带该突变。结论在中国汉族人念珠状发患者中检测到了hHB6基因c．1204G〉A（p．E402K）突变，由母亲遗传给其女儿。结果表明毛发角蛋白hHB6在念珠状发发病机制中起关键的作用，初步显示hHB6基因常见c．1204G〉A（P．E402K）突变也是导致中国人患念珠状发的原因。

英文摘要：

Objective To identify the human hair basic keratin 6 gene （hHB6 ） mutation in a mother and her daughter with monilethrix, Methods Clinical data were obtained by investigating the pedigree and examining the patients＇ hair and skin. Total genomic DNA of the family participants was isolated, All exons and exon-intron boundaries of hHB6 were amplified by PCR. Mutation screening was carried out using direct DNA sequencing. Restriction fragment length polymorphism （RFLP） analysis was used to confirm the mutation, and to investigate if the mutation co-segregated with the disease in the family and existed in normal controls. Results A heterozygous transition of c. 1204G 〉 A （p. E402K） of hHB6 was identified. RFLP analysis demonstrated that affected members carried the p, E402K mutation, but the unaffected members of the family and 150 unrelated normal Chinese Han nationality controls did not carry the muta- tion. Conclusion This study identified the hHB6 gene mutation e. 1204G 〉 A （p. E402K） in a Chinese monilethrix family. The mutation was inherited from the mother to her daughter. The results emphasized the key role of hair keratin hHB6 in the pathogenesis of monilethrix and indicated that the common mutation of hHB6 was also a cause of monilethrix in Chinese,