CYP19A1 and metabolic syndrome: Males with decreased aromatase levels experience greater risk of abdominal obesity, elevated blood lipid levels, and insulin resistance.13,18,19 These metabolic changes are also observed in males receiving antiandrogen treatment for prostate cancer and in males with Klinefelter syndrome (XXY sex chromosomes).20,21 XX chromosome–associated increased risk of metabolic syndrome is further supported by mouse model studies showing that presence of 2 X chromosomes in male mice promotes increased body fat and elevated plasma cholesterol levels.22,23