Monosomy for the X-chromosome is associated with an atherogenic lipid profile

Context and Objective: Men typically have a more atherogenic lipid profile than women characterized by higher low-density lipoprotein (LDL) cholesterol and triglyceride levels and reduced lipid particle size, contributing to a greater risk for coronary disease. To determine whether X-chromosomal gene dosage affects lipid metabolism independent of sex steroid effects, we compared lipid profiles in age- and body mass-matched young women with ovarian failure, differing only in X-chromosome dosage. Design, Setting, and Patients: Women with premature ovarian failure associated with monosomy X or Turner syndrome (TS, n = 118) were compared with women with 46,XX premature ovarian failure (n = 51) in an in-patient clinical research center unit at the National Institutes of Health. These women were normally on estrogen replacement treatment but discontinued the estrogen 2 wk before study. Major Outcomes: Fasting lipid levels and nuclear magnetic resonance lipid particle profiles in the two study groups were the major outcomes. Results: Average age and body mass were similar in the two groups of women, but LDL cholesterol (P = 0.001) and triglyceride levels (P = 0.0005) were higher in the TS group. Also among women with TS, average LDL particle size was reduced (P < 0.0001) and LDL particle concentration increased, with a 2-fold increase in the smallest particle categories (P < 0.0001). Whereas total high-density lipoprotein cholesterol levels were similar, high-density lipoprotein particle size was significantly smaller in women with TS, compared with women with premature ovarian failure (P < 0.0001). Conclusions: Women with 45,X with ovarian failure exhibit a distinctly more atherogenic lipid profile than 46,XX women with ovarian failure, suggesting that the second X-chromosome contributes to a more salutary lipid profile in normal women, independent of sex steroid effects.