常染色体隐性遗传念珠状发一家系DSG4基因突变研究

Desmoglein 4 gene mutation analysis in a pedigree with autosomal recessive hereditary monilethrix

先证者女,3岁,出生后头皮可见片状毛囊角化性丘疹,无毛发生长。2岁左右头部开始生长稀疏毛发,粗细不均,间断脱落,触之易断。部分眉毛、睫毛脱落、折断,长短不一。体检:营养良好,身高、体重及智力正常,其他系统检查无明显异常。皮肤科检查:头皮顶部、枕部片状毛发稀疏、脱落,残留断发及毛囊角化性丘疹。牙齿、指甲、趾甲及汗腺正常。病发在皮肤镜、光镜及扫描电镜下均表现为念珠状发。基因测序显示,先证者桥粒芯糖蛋白4(DSG4)基因2~16号外显子杂合缺失,并且携带DSG4基因c.574T>C(p.S192p)(NM-177986)杂合突变;先证者母亲携带DSG4基因2~16号外显子杂合缺失突变;先证者父亲携带DSG4基因c.574T>C(p.S192p)杂合突变。100例健康人对照DSG4基因均未发现上述位点突变。结合患儿基因检测结果及临床表型,最终诊断为常染色体隐性遗传念珠状发,推测DSG4基因c.574T>C突变和2~16号外显子缺失突变是导致本例患儿发生念珠状发的原因。

A 3-year-old female proband presented with patchy follicular keratotic papules on the hairless scalp after birth.At about the age of 2 years,sparse hairs of non-uniform thickness began to grow,but they fell out intermittently and were broken easily.Some eyebrows and eyelashes of different lengths fell out or were broken.Physical examination revealed good condition of nutrition,normal height,weight and intelligence,with no obvious abnormalities in other systems.Skin examination showed sparse and broken hairs with follicular keratotic papules on the vertex and occiput.Teeth,nails,toenails and sweat glands were normal.Dermoscopy,optical microscopy and scanning electron microscopy all showed that affected hairs gave a beaded appearance.Gene sequencing showed that the proband carried heterozygous deletions of exons 2-16 in the desmoglein 4(DSG4)gene,and a heterozygous mutation c.574T>C(p.S192p)(NM-177986)in the DSG4 gene,which were inherited from her father and mother respectively.None of the above mutations in the DSG4 gene were found in 100 healthy controls.According to the gene sequencing results and clinical phenotype,the patient was finally diagnosed with autosomal recessive hereditary monilethrix,and the c.574T>C mutation and heterozygous deletions of exons 2-16 of the DSG4 gene may contribute to autosomal recessive hereditary monilethrix in the child.