Study On The Clinical Characteristics And The Genetic Mutations Of 17α-hydroxylase/17, 20-lyase Deficiency

Study on the clinical characteristicsand the genetic mutations of 17 α -hydroxylase/17,20-lyasedeficiencyObjective17 α -hydroxylase / 17, 20 -lyase deficiency is a rare cause of congenital adrenal hyperplasia, accounting for less than 1%. Human has only one gene, CYP17, that encodes these two enzymes (so is also called P450c17 enzyme ) and expresses both in adrenals and gonads. It has been confirmed that CYP17 gene is located on chromosome 10q24.3, containing 8 exons and 7 introns. The typical clinical characteristics of 17 α -hydroxylase deficiency are hypertension, hypokalemia and absence of sexual development. From then, considerable variation in phenotype and laboratory findings has been described. People found not only existing complete combined deficiency of 17α -hydroxylase/17, 20 -lyase, but also partial combined deficiency of these two enzymes. On the other hand, isolated 17, 20 -lyase deficiency was also described in the literature. In recent decade the genetic analysis of this defect was reported. Up to date, more than 30 mutations of CYP17 gene have been identified. The expression of mutated P450cl7 protein in COS-1 cells showed that different mutations may reduce the enzyme activities in different degree. In China, more than 20 cases of this disease were reported, and the genetic mutations were detected in 5 cases among them .But all of these were complete combined forms of the defect. The aim of these study was to improve the diagnosis and the treatment through the clinical retrospectively analysis of 24 cases of the disease in this hospital and look at the gene mutations in 7 cases among them.