FRAXA and FRAXE prevalence in patients with nonspecific mental retardation in the Hellenic population

Syrrou, Maria; Georgiou, Ioannis; Grigoriadou, Maria; Petersen, Michael B.; Kitsiou, Sofia; Pagoulatos, Gerassimos N.; Patsalis, Philippos C.

doi:10.1002/(sici)1098-2272(1998)15:1<103::aid-gepi8>3.3.co;2-l

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…Employing the DNA diagnostic methods, another report from Southern India revealed a frequency of 7%, comparable to our results [Baskaran et al, 1998]. However, we cannot compare our results with those reported for most other Western institutionalized populations, which included all unexplained MR cases in their study samples [Meadows et al, 1996;Mila et al, 1997;Elbaz et al, 1998;Syrrou et al, 1998;Crawford et al, 1999;Pang et al, 1999;Patsalis et al, 1999]. Considering the stringent selection criteria employed in this study, the overall frequency of FXS in India may be very similar to that reported for other Western and Asian populations [Patsalis et al, 1999].…”

Section: Discussionsupporting

confidence: 84%

Expansion mutation frequency and CGG/GCC repeat polymorphism inFMR1 andFMR2 genes in an Indian population

2000

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Based on molecular screening, we estimated the frequencies of fragile X syndrome and FRAXE syndrome in an institutionalized population (n = 130) in New Delhi, India. Eligibility criteria for inclusion of subjects in the study were mild/moderate mental retardation, with/without family history, and the fragile X clinical phenotype. Screening by Southern hybridization revealed an overall frequency of 0.077 of the syndrome in the sample population. The disorder was observed with a high frequency (0.1) among males as compared to females (0.027). No expansions of FMR2 allele were observed in the same study sample. CGG/GCC allelic polymorphism of FMR1 and FMR2 were established from a total of 392 X chromosomes, using the radioactive polymerase chain reaction–polyacrylamide gel electrophoresis method. Distinct repeat sizes, repeat ranges, and repeat modes characterised the FMR1 and FMR2 alleles. In the X chromosomes of both MR individuals and unaffected controls, unimodal values of 29 and 15 repeats in FMR1 and FMR2 genes, respectively, were observed. Allele frequency distribution was symmetrical at the FMR1 locus whereas a significant positive skew was observed for the FMR2 alleles. The observed heterozygosity of the FMR1 gene was 0.772 compared to 0.839 of FMR2. Correlation of CGG/GCC repeats of FMR1 and FMR2 did not show any association of repeat sizes at these two loci (correlation coefficient, ρ = 0.09). CGG/GCC repeat variation at FMR1 and FMR2 loci observed in this study sample are different from that reported for the other Caucasian and Asian populations. Genet. Epidemiol. 20:129–144, 2001. © 2001 Wiley‐Liss, Inc.

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Section: Discussionsupporting

confidence: 84%

Expansion mutation frequency and CGG/GCC repeat polymorphism inFMR1 andFMR2 genes in an Indian population

2000

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“…The prevalence 1/3,460 (CI 1/7,143-1/1,742) estimated here for FRAXA syndrome in a white male population is in agreement with that determined in previous studies (Murray et al 1996;Turner et al 1996;de Vries et al 1997;Morton et al 1997;Syrrou et al 1998). On the basis of this estimate, we project the prevalence among females to be ∼1/9,000, assuming that ∼50% of female full-mutation carriers exhibit the syndrome (Rousseau et al 1994) and that the frequency of male and female full-mutation carriers is equal (Sherman 1995a).…”

Section: Prevalencesupporting

confidence: 92%

Prevalence and Phenotype Consequence of FRAXA and FRAXE Alleles in a Large, Ethnically Diverse, Special Education–Needs Population

Crawford

Meadows

Newman

et al. 1999

The American Journal of Human Genetics

120

117

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We conducted a large population-based survey of fragile X (FRAXA) syndrome in ethnically diverse metropolitan Atlanta. The eligible study population consisted of public school children, aged 7-10 years, in special education-needs (SEN) classes. The purpose of the study was to estimate the prevalence among whites and, for the first time, African Americans, among a non-clinically referred population. At present, 5 males with FRAXA syndrome (4 whites and 1 African American), among 1,979 tested males, and no females, among 872 tested females, were identified. All males with FRAXA syndrome were mentally retarded and had been diagnosed previously. The prevalence for FRAXA syndrome was estimated to be 1/3,460 (confidence interval [CI] 1/7,143-1/1,742) for the general white male population and 1/4, 048 (CI 1/16,260-1/1,244) for the general African American male population. We also compared the frequency of intermediate and premutation FRAXA alleles (41-199 repeats) and fragile XE syndrome alleles (31-199 repeats) in the SEN population with that in a control population, to determine if there was a possible phenotype consequence of such high-repeat alleles, as has been reported previously. No difference was observed between our case and control populations, and no difference was observed between populations when the probands were grouped by a rough estimate of IQ based on class placement. These results suggest that there is no phenotype consequence of larger alleles that would cause carriers to be placed in an SEN class.

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“…Since the advent of molecular testing, we as well as others have examined the prevalence of the fragile X syndrome among males with specific cognitive or behavioral problems and have extrapolated the estimate to the general population. This has been done primarily for males of mostly northern European descent, and the prevalence was estimated at 1/6,000 to 1/4,000 males in the general population [Murray et al, 1996; Turner et al, 1996; Morton et al, 1997; de Vries et al, 1997; Syrrou et al, 1998; Crawford et al, 1999; Youings et al, 2000]. In our previous report, we estimated the prevalence of the fragile X syndrome as well as the other forms of the FMR1 alleles in a Caucasian and African‐American population of children in special education classes in the public school system residing in the four counties of metropolitan Atlanta, Georgia [Crawford et al, 1999].…”

Section: Introductionmentioning

confidence: 99%

Prevalence of the fragile X syndrome in African‐Americans

et al. 2002

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Since the development of a molecular diagnosis for the fragile X syndrome in the early 1990s, several population-based studies in Caucasians of mostly northern European descent have established that the prevalence is probably between one in 6,000 to one in 4,000 males in the general population. Reports of increased or decreased prevalence of the fragile X syndrome exist for a few other world populations; however, many of these are small and not population-based. We present here the final results of a 4-year study in the metropolitan area of Atlanta, Georgia, establishing the prevalence of the fragile X syndrome and the frequency of CGG repeat variants in a large Caucasian and African-American population. Results demonstrate that one-quarter to one-third of the children identified with the fragile X syndrome attending Atlanta public schools are not diagnosed before the age of 10 years. Also, a revised prevalence for the syndrome revealed a higher point estimate for African-American males (1/2,545; 95% CI: 1/5,208-1/1,289) than reported previously, although confidence intervals include the prevalence estimated for Caucasians from this (1/3,717; 95% CI: 1/7,692-1/1,869) and other studies. Further population-based studies in diverse populations are necessary to explore the possibility that the prevalence of the fragile X syndrome differs among world populations.

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FRAXA and FRAXE prevalence in patients with nonspecific mental retardation in the Hellenic population

Cited by 3 publications

References 7 publications

Expansion mutation frequency and CGG/GCC repeat polymorphism inFMR1 andFMR2 genes in an Indian population

Expansion mutation frequency and CGG/GCC repeat polymorphism inFMR1 andFMR2 genes in an Indian population

Prevalence and Phenotype Consequence of FRAXA and FRAXE Alleles in a Large, Ethnically Diverse, Special Education–Needs Population

Prevalence of the fragile X syndrome in African‐Americans

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