A common polymorphism in the CYP3A7 gene is associated with a nearly 50% reduction in serum dehydroepiandrosterone sulfate levels

Abstract

Context: CYP3A7, expressed in the human fetal liver and normally silenced after birth, plays a major role in the 16α-hydroxylation of dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), and estrone. Due to a replacement of part of the CYP3A7 promoter with a sequence identical with the same region in the CYP3A4 promoter (referred to as CYP3A7*1C), some individuals still express a variant of the CYP3A7 gene later in life. Objective: The objective of this study was to examine the effect of the CYP3A7*1C polymorphism on serum steroid hormone levels. Design, Setting, Participants: Two population-based cohort studies were performed. Study group 1 consisted of 208 subjects randomly selected from the Rotterdam Study, and study group 2 consisted of 345 elderly independently living men. Main Outcome Measures: Serum DHEA(S), androstenedione, estradiol, estrone, and testosterone levels were the main outcome measures. Results: In study groups 1 and 2, heterozygous CYP3A7*1C carriers had almost 50% lower DHEAS levels compared with homozygous carriers of the reference allele [study group 1, 1.74 ± 0.25 vs. 3.33 ± 0.15 μmol/liter (P < 0.02); study group 2, 2.09 ± 0.08 vs. 1.08 ± 0.12 μmol/liter (P < 0.001)]. No differences in circulating DHEA, androstenedione, estradiol, or testosterone levels were found. However, in study group 2, serum estrone levels were lower in heterozygous CYP3A7*1C carriers compared with homozygous carriers of the reference allele (0.11 ± 0.002 vs. 0.08 ± 0.006 nmol/liter; P < 0.001). Conclusion: The CYP3A7*1C polymorphism causes the persistence of enzymatic activity of CYP3A7 during adult life, resulting in lower circulating DHEAS and estrone levels. Copyright © 2005 by The Endocrine Society.