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.     

The genetic analysis of monilethrix in a large inbred kindred

The gene for monilethrix was segregating in a large inbred kindred. Pedigree analysis reaffirms an autosomal dominant mode of inheritance. Expressivity appears equally variable within and between sibships while penetrance, in contrast to previous studies, seems to be complete.     

中国汉族人念珠状发患者hHB6基因突变检测

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-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＞A(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.     

全身毛发受累的念珠形发1例

报告1例21岁男性患者，自幼头发稀少，头部营养不良性秃发，全身毛发程度不一的串珠状改变或黑点状断发，伴毛囊角化性丘疹。光镜见典型串珠状改变。扫描电镜观察胸毛，一根毛小皮消失，一根存在，狭窄部见明显的纵嵴，纵沟。病理见毛囊稀少、萎缩。     

Monilethrix: a keratin hHb6 mutation is co-dominant with variable expression

Monilethrix is a rare autosomal dominant disease characterized by hair fragility and hyperkeratotic papules. Mutations in type-II hair specific keratins hHb6 and hHb1 have recently been reported. We describe a large family with a E410D mutation in the evolutionary conserved helix termination motif of keratin hHb6 that was variably expressed among 12 heterozygous members, and severely expressed among 3 homozygous members. These 3 patients had essentially complete lack of scalp hair since the age of 2 months with no improvement over time as well as follicular keratotic involvement extensively expressed over the scalp and large body areas. The variability seen in heterozygous patients, along with seasonal and pregnancy-related improvement suggest that other genetic or environmental factors may modify keratin gene expression. This represents the first report of a co-dominant keratin hHb6 mutation resulting in severe disease.     

念珠状发四例

念珠状发是一种常染色体显性遗传性皮肤病,以毛干和毛囊结构异常为特征。本文报道4例,均表现为头发易折断,生长缓慢,其中3例有家族史。4例患者皮肤镜检查均可见梭形膨大和明显缩窄交替出现的典型念珠状改变。有2例患者进行了KRT86基因检测,分别检测到c.1204GA和c.1237GA的突变。     

Lanceolate hair-J (lahJ): a mouse model for human hair disorders

Lanceolate hair-J (lahJ) arose spontaneously in 1994 on the DBA/1LacJ inbred background at The Jackson Laboratory. Mutant mice were runted, alopecic, and lacked vibrissae. As they aged, their skin wrinkled. Affected mice developed a noninflammatory, proliferative skin disease with follicular dystrophy. Hair fibers developed a number of abnormalities including periodic nodules along the shaft (trichorrhexis nodosa), compaction resembling trichorrhexis invaginata, spiral fractures, broken tips, and lance-shaped tips. This mutation exhibits some characteristics that resemble an autosomal recessive ichthyosiform disease that occurs in humans characterized in part by peculiar, invaginating, multinodal, hair shaft abnormalities known as Netherton's syndrome. Periodic nodules also resemble the human genetic based disease monilethrix. This autosomal recessive mouse mutation, allelic with lanceolate hair (lah), based on breeding studies, is located on mouse Chromosome 18, within a cluster of genes coding for adhesion molecules. Homozygotes for either of these allelic mouse mutations have elevated serum IgE levels, a feature also common with human Netherton's syndrome.     

Hair shaft abnormalities: Part I

The light microscopic and electron microscopic appearances of the normal hair are briefly described. The major hair shaft abnormalities are reviewed in two parts, discussing clinical characteristics, light and electron microscopy and, where information is available, the pathogenesis of these rare conditions. Part I describes monilethrix, pili torti and trichorrhexis nodosa.