两个21-羟化酶缺乏症家系的CYP21A2基因突变分析

Analysis of CYP21A2 gene mutation in two families with 21-hydroxylase deficiency

目的对两个21-羟化酶缺乏症（21-hydroxylasedeficiency，21-OHD）家系进行CYP21A2基因突变分析，并探讨基因型与临床表型的关系。方法分析2例21一OHD先证者的临床资料，应用直接测序法对2个21-OHD家系先证者及家系成员进行CYP21A2基因突变分析。结果家系1先证者临床诊断为单纯男性化型；家系2先证者临床诊断为非经典型。两先证者均存在基础血清17-羟孕酮、睾酮、促肾上腺皮质激素升高，无失盐证据，CT均示双侧肾上腺皮质增生。治疗1年后均成功受孕。基因测序结果显示，家系1先证者存在CYP21A2基因IVS2—13A〉G和Ilel72Asn复合杂合突变，其父亲存在Ilel72Asn杂合突变，其母亲和弟弟存在IVS2-13A〉G杂合突变；家系2先证者存在CYP21A2基因Arg341Trp和GIn318X复合杂合突变，其父亲、姐姐和外甥存在Arg341Trp杂合突变，其母亲存在GIn318X杂合突变，其哥哥和侄女未发现突变位点。两家系成员中杂合突变携带者均无21-OHD的临床表现。结论两例先证者均由复合杂合突变致病，基因型与临床表型有较好的一致性，进一步行CYP21A2基因筛查有助于明确诊断和遗传咨询。

Objective To analyze CYP21A2 gene mutation in two families with 21-hydroxylase deficiency （21-OHD） and to explore the correlation between genotype and clinical phenotype. Methods Two patients with 21-OHD and their families were investigated. CYP21A2 gene mutation was analyzed by PCR and direct sequencing. Results The probands from family 1 and 2 have been respectively diagnosed with simple virilizing and non-classical 21-OHD. Both showed increased baseline serum 17- hydroxyprogesterone, testosterone and adrenocorticotropic hormone （ACTH）, but had no evidence of salt loss. Computer tomography revealed bilateral adrenal hyperplasia in both patients. After 1 year treatment, both had conceived successfully. DNA sequencing revealed that the proband of family 1 had compound heterozygous mutations for IVS2 -13 A〉G and Ile172Asn. Her father was heterozygous for Ile172Asn, whilst her mother and brother were heterozygous for IVS2-13A/C〉G. In family 2, the proband was heterozygous for Arg341Trp and Gln318X. Her father, sister and nephew were heterozygous for Arg341Trp, whilst her mother was heterozygous for Gln318X. her brother and niece were non-affected. Carriers of single heterozygous mutations in both families had no clinical sign. Conclusion In both families, the disease has been caused by compound heterozygous mutations, for which there has been a good genotype-phenotype agreement. Screening of CYP21A2 gene can facilitate both diagnosis and genetic counseling.