The frequency of the fragile X chromosome among schoolchildren in Coventry.

Abstract

A population study has been carried out among schoolchildren in the City of Coventry in order to ascertain the frequency of mental retardation associated with the fragile X chromosome. The prevalence of the fragile X mental retardation syndrome in the 11 to 16 year age group (the age of greatest ascertainment) was about 1 0 per 1000 and therefore indicates that the syndrome is a major cause of mental retardation. Estimates of the prevalence of mental retardation in males associated with the fragile X chromosome have ranged from 0-19 to 0-92 per 10O0.'-I A study based on schools for the educationally subnormal (ESN) in Coventry has enabled us to estimate the prevalence of the fragile X chromosome in schoolchildren of that city, in both males and females. Methods The study took place between 1 April 1982 and 31 December 1985. Children were included if they were born before 31 August 1978 and if they were at school during the study period. We studied children with home addresses in Coventry who either lived at home and attended day schools for the educationally subnormal (ESN) or who were in residential care, either in or outside the city. We visited four ESN(S) and four ESN(M) schools in Coventry together with one mental deficiency hospital and two schools for the physically handicapped. We also examined at home two children who were resident during term time at schools outside Coventry. We chose to study certain groups of children among whom we anticipated that some would have the fragile X chromosome associated with their mental retardation. It was necessary to omit certain groups in whom the fragile X chromosome was less likely to be found because the techniques required to identify the fragile X chromosome are laborious4 5

Fragile X screening for FRAXA and FRAXE mutations using PCR based studies: Results of a five year study

“…[4] In 1986, a population study of school children in the city of Coventry gave an overall prevalence of 1/952 in males and females for fragile X syndrome. [16] Later on many of these children diagnosed as having fragile X syndrome based on cytogenetic method were found negative on molecular studies. So in 1997 a revised prevalence figure of 1/2720 males was calculated based on molecular investigations.…”

Cytogenetic Diagnosis of Fragile X Syndrome: Study of 305 Suspected Cases in Saudi Arabia

“…[18][19] Prevalences of 0.4-0.8/1000 in males and 0.2-0.6/1000 in females were reported based on cytogenetic screening. [20][21][22][23] However, de Vries recently reported a prevalence of 0.6% by combining DNA analysis studies from Europe, Australia and the United States. 24 The frequency of new fragile X cases may.…”

FMR1 and the fragile X syndrome: Human genome epidemiology review

“…34 Several studies published in the 1980s using the fragile site as a diagnostic tool estimated that the prevalence of the syndrome was as high as 1 in 1,500 males and 1 in 2,500 females in the general population. 35,36 The cytogenetic test employed by these studies has since been shown to be inaccurate, generating both false-negative and false-positive results. 37 The cloning of the CGG repeat responsible for the fragile X syndrome provided the opportunity for a more accurate diagnosis using molecular techniques.…”