Leung Mei Tik, Cheung Hoi Ning, Iu Yan Ping, Choi Cheung Hei, Tiu Sau Cheung, Shek Chi Chung
Department of Pathology, Queen Elizabeth Hospital, Jordan, Kowloon, Hong Kong.
Department of Medicine, Queen Elizabeth Hospital, Jordan, Kowloon, Hong Kong.
J Endocr Soc. 2019 Nov 18;4(2):bvz016. doi: 10.1210/jendso/bvz016. eCollection 2020 Feb 1.
Isolated 17,20-lyase deficiency may be caused by mutations in the (coding for cytochrome P450c17), (coding for cytochrome P450 oxidoreductase) and (coding for microsomal cytochrome b5) genes. Of these, mutations in the gene have thus far only been described in genetic males who presented with methemoglobinemia and 46,XY disorders of sex development (DSD) due to 17,20-lyase deficiency. A 24-year-old Chinese woman presented to the hematology outpatient clinic with purplish discoloration of fingers, toes, and lips since childhood. Investigations confirmed methemoglobinemia. A homozygous c.105C>G (p.Tyr35Ter) nonsense mutation was detected in the gene. Hormonal studies showed isolated 17,20-lyase deficiency. Interestingly, she had a completely normal female phenotype with no DSD, normal pubertal development, and spontaneous pregnancy giving birth uneventfully to a healthy female infant. The sex hormone-related features of genetic females with 17,20-lyase deficiency due to cytochrome b5 gene mutation appear to differ from that of females with 17,20-lyase deficiency caused by other genetic defects who presented with hypergonadotropic hypogonadism and infertility and differ from genetic males with the same mutation.
孤立性17,20-裂解酶缺乏症可能由（编码细胞色素P450c17）、（编码细胞色素P450氧化还原酶）和（编码微粒体细胞色素b5）基因的突变引起。其中，基因的突变迄今仅在因17,20-裂解酶缺乏症而出现高铁血红蛋白血症和46,XY性发育障碍（DSD）的遗传男性中被描述。一名24岁的中国女性自幼手指、脚趾和嘴唇出现紫色变色，前往血液科门诊就诊。检查确诊为高铁血红蛋白血症。在基因中检测到纯合的c.105C>G（p.Tyr35Ter）无义突变。激素研究显示孤立性17,20-裂解酶缺乏症。有趣的是，她具有完全正常的女性表型，没有DSD，青春期发育正常，自然受孕并顺利产下一名健康女婴。因细胞色素b5基因突变导致17,20-裂解酶缺乏症的遗传女性的性激素相关特征似乎与因其他遗传缺陷导致17,20-裂解酶缺乏症且表现为高促性腺激素性性腺功能减退和不孕的女性不同，也与具有相同突变的遗传男性不同。
