Legend: Fig. 1. Frequency of specific CGG repeat lengths >40 for men and women.
Citation: Maenner MJ, Baker MW, Broman KW, Tian J, Barnes JK, Atkins A, McPherson E, Hong J, Brilliant MH, Mailick MR. (2013). FMR1 CGG expansions: prevalence and sex ratios. American Journal of MedicalGenetics Part B: Neuropsychiatric Genetics. 162B(5):466-73.
Abstract: We have estimated the prevalence of FMR1 premutation and gray zone CGG repeat expansions in a population-based sample of 19,996 male and female adults in Wisconsin and compared the observed sex ratios of the prevalence of FMR1 CGG premutation and gray zone expansions to theoretical sex ratios. The female premutation prevalence was 1 in 148 and comparable to past research, but the male premutation prevalence of 1 in 290 is somewhat higher than most previous estimates. The female:male premutation prevalence ratio is in line with the theoretically predicted sex ratio. The prevalence of CGG repeats in the gray zone (45-54 repeats) was 1 in 33 females and 1 in 62 males. The prevalence of the “expanded” gray zone (defined here as 41-54 CGG repeats) was 1 in 14 females and 1 in 22 males, leading to a female:male ratio of 1.62 (95% confidence interval 1.39-1.90). This female:male ratio was significantly lower than the expected ratio of 2.0. We examined results from three previously published FMR1 prevalence studies and found similar female:male ratios for CGG repeats in this “expanded” gray zone range (pooled female:male ratio across all four studies 1.66, 95% confidence interval 1.51-1.82). Further research is needed to understand the apparent excess prevalence of males with CGG repeats in this range.
About the Lab: The Lifespan Family Research Program is dedicated to the advancement of knowledge about families who have a member with a disability, with a special emphasis on how these families change over the lifespan. Our program of research currently encompasses three ongoing studies, one focused on autism, another on fragile X syndrome, and on population studies. Previous studies have been directed at other developmental disabilities, such as Down syndrome, severe mental illnesses, women as caregivers, and on families of color.