SRD5A2基因新复合杂合功能缺失突变导致性腺发育异常分析

Novel compound heterozygous LoF mutations in SRD5A2 may result in disorders of sex development

目的鉴定与尿道下裂相关的新单碱基变异及探讨该类患者子代遗传缺陷预防策略。方法2019年3月上海交通大学附属第一人民医院临床收治性腺发育异常(尿道下裂伴隐睾)患者1例,通过体格检查、性激素检查、男性生殖系统B超及CT评估其男性第二性征发育、性激素水平以及男性生殖系统发育情况;利用全外显子测序(WES)检测患者与尿道下裂及隐睾相关致病基因突变位点;Sanger测序验证其家系致病基因突变位点及遗传方式;精液分析评估其生育力;并对其配偶进行类固醇5α-还原酶2(SRD5A2)基因分析,评估子代遗传缺陷风险。结果患者性腺发育异常,表现为尿道下裂伴隐睾。体格检查示患者阴毛呈倒三角分布,阴茎短小,双侧睾丸体积约8 ml。性激素检查示:卵泡刺激素(FSH)25.81 U/L,黄体生成素(LH)10.84 U/L,垂体泌乳素21.09μg/L,雌二醇(E2)153 pmol/L,睾酮16.95 nmol/L,性激素结合球蛋白36.15 nmol/L。B超提示左侧腹股沟隐睾。精液分析示:精液量为0.05 ml,精子浓度<2×106/ml,为严重少精子症。WES及Sanger PCR结果提示患者存在SRD5A2基因复合杂合功能缺失(LoF)突变[NM_000348.3:C.679C>T(p.Arg227Ter)和NM_000348.3:C.16C>T(p.Gln6Ter)],其配偶SRD5A2基因无致病突变。结论新SRD5A2复合杂合突变[NM_000348.3:C.679C>T(p.Arg227Ter)和NM_000348.3:C.16C>T(p.Gln6Ter)]可以导致性腺发育异常。

Objective To investigate the novel genetic cause associated with hypospadias and the strategy for preventing offspring genetic defects in these patients.Methods In March 2019,a patient with gonadal dysplasia(hypospadias associated with cryptorchidism)was referred to Shanghai General Hospital.His secondary sex characters,level of sex hormones and the development of male reproductive system was assessed through physical examination,sex hormone examination,male reproductive system B-ultrasound and computed tomography(CT).Whole-exome sequencing(WES)was preformed to investigate the pathogenic genetic variations associated with hypospadias and cryptorchidism.Also,Sanger sequencing was conducted to verify the WES results in the pedigree.Semen analysis was used to assess the fertility of the proband and the SRD5A2 gene analysis of his spouse was performed to assess the risk of genetic defects in the offspring.Results The patient suffered from gonadal dysplasia(hypospadias associated with cryptorchidism).Physical examination showed an inverted triangular distribution of pubic hair,small penis and the volume of the testis was 8 ml.Sex hormone examination revealed the level of FSH,LH,Pituitary prolactin(PRL),estrogen(E2),testosterone(T),and sex hormone-binding globulin(SHBG)was 25.81 U/L,10.84 U/L,21.09μg/L,153 pmol/L,16.95 nmol/L,and 36.15 nmol/L respectively.B-ultrasound and computed tomography(CT)showed left inguinal testis.Also,semen analysis illustrated that the volume was 0.05 ml and sperm concentration<2×106/ml,suggesting oligospermia in this case.WES sequencing and Sanger sequencing showed compound heterozygous LoF mutations in SRD5A2[NM_000348.3:C.679C>T(p.Arg227Ter)and NM_000348.3:C.16C>T(p.Gln6Ter)]in this patient.And there were no pathogenic genetic variations of SRD5A2 in the spouse.Conclusion Novel compound heterozygous LoF mutations in SRD5A2[NM_000348.3:C.679C>T(p.Arg227Ter)and NM_000348.3:C.16C>T(p.Gln6Ter)]may be the primary cause of disorders of sex development.