Functional Identification of Compound Heterozygous Mutations in the CYP17A1 Gene Resulting in Combined 17α-Hydroxylase/17,20-Lyase Deficiency

BACKGROUND: We previously reported a patient with congenital adrenal hyperplasia (CAH) with compound heterozygous mutations in the cytochrome P450 17A1 (CYP17A1) gene. One allele had a p.His373Leu and the other a new p.Glu383fsX36 mutation. The aim of this study was to investigate the functional properties of a new allele present in a compound heterozygote of CYP17A1. METHODS: To understand how p.His373Leu and p.Glu383fsX36 affect P450c17 enzymatic activity, wild type and mutant CYP17A1 cDNAs were cloned into flag-tagged pcDNA3 vector and introduced into human embryonic kidney cells 293T (HEK293T) cells. Protein expression levels of CYP17A1 were then analyzed. And the activities of 17α-hydroxylase and 17,20-lyase of CYP17A1 were evaluated by measuring the conversion of progesterone to 17α-hydroxyprogesterone and of 17α-hydroxypregnenolone to dehydroepiandrosterone, respectively. In addition a computer model was used to create the three-dimensional structure of the mutant CYP17A1 enzymes. RESULTS: Production of the p.His373Leu mutant protein was significantly lower than that of the wild type protein, and the p.Glu383fsX36 protein was hardly produced. Similarly the enzymatic activity derived from the p.His373Leu mutant vector was significantly lower than that obtained from the wild type vector, and little activity was obtained from the p.Glu383fsX36 vector. Three-dimensional modeling of the enzyme showed that p.His373 was located in region important for heme-binding and proper folding. Neither the p.His373Leu nor the p.Glu383fsX36 mutant protein formed a heme-binding structure. CONCLUSION: Enzyme activity measured in both mutants disappeared completely in both 17α-hydroxylase and 17,20-lyase. This result accounts for the clinical manifestations of the patient with the compound heterozygous CYP17A1 mutations.

Are the Requirements of Propofol Decreased in Early Pregnancy during Anesthetic Induction? / 대한마취과학회지

BACKGROUND: Minimum alveolar concentration (MAC) is decreased during pregnancy, but there are no data regarding the requirements for intravenous agents. Recently only one study showed that the requirement for thiopental in pregnant women of 7-13 weeks' gestation was less than the requirement obtained in nonpregnant women. Thus we wanted to determine whether pregnant patients needed less propofol for hypnosis and anesthesia than nonpregnant patients. METHODS: One hundred nonpregnant women having gynecologic surgery and 100 pregnant women of 5-13 weeks' gestation undergoing elective abortions were recruited. They were randomly allocated 10 groups according to the doses of propofol and each group had 10 patients. During a period of 30 seconds, one of the doses of propofol 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0 or 3.25 mg/kg was administered. Two minutes later, patients were asked to open their eyes as a test for hypnosis. Patients who did not open their eyes were given a 10 seconds, 50-Hz, 80-mA transcutaneous tetanic electrical stimulus to the ulnar nerve as a test for anesthesia. Estimates of ED50 and ED95 for hypnosis and anesthesia were obtained by logistic regression. RESULTS: In the pregnant women, the median effective doses (ED50) (95% confidence interval) for hypnosis and anesthesia were 1.25 (1.13-1.35) mg/kg and 2.71 (2.49-3.04) mg/kg, the ED95 (95% CI) were 1.51 (1.16-1.87) mg/kg and 3.04 (2.80-3.58) mg/kg respectively. Whereas in the nonpregnant women, the ED50 for hypnosis and anesthesia were 1.27 (1.39-1.90) mg/kg and 4.12 (3.50-6.01) mg/kg, the ED95 were 1.53 (1.41-1.93) mg/kg and 4.35 (3.66-7.26) mg/kg respectively. CONCLUSIONS: In early pregnant women, the doses of propofol for hypnosis and anesthesia were 1.6% and 34.2% less compared with those in nonpregnant women.