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FMR1 CGG expansions: Prevalence and sex ratios
Author(s) -
Maenner Matthew J.,
Baker Mei W.,
Broman Karl W.,
Tian Jianan,
Barnes Janel K.,
Atkins Anne,
McPherson Elizabeth,
Hong Jinkuk,
Brilliant Murray H.,
Mailick Marsha R.
Publication year - 2013
Publication title -
american journal of medical genetics part b: neuropsychiatric genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.393
H-Index - 126
eISSN - 1552-485X
pISSN - 1552-4841
DOI - 10.1002/ajmg.b.32176
Subject(s) - fmr1 , confidence interval , sex ratio , demography , gray (unit) , fragile x syndrome , population , biology , male to female , epidemiology , medicine , genetics , fragile x , nuclear medicine , sociology , gene
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. © 2013 Wiley Periodicals, Inc.