RESUMEN
Fragile-X syndrome (FXS) is the most common cause of inherited intellectual disability. Although FXS has been identified in all the main ethnic groups, little is known about its prevalence with respect to ethnicity. Since the identification of the FXS primary defect, diagnosis involving DNA analysis has been made possible, allowing efficient screening strategies to be considered. The present authors have carried out FXS screening among children belonging mainly to the Afro-Caribbean ethnic group (163 boys and 85 girls) affected with moderate to severe intellectual disability of previously unknown origin. We have found a 6.7% and 0% prevalence among boys and girls, respectively, yielding a minimum FXS incidence of 0.42 per 1000 male births per year. Family studies have resulted in genetic counselling for several individuals. FRAXE screening was also achieved and no FRAXE case was detected in this study.
Asunto(s)
Negro o Afroamericano/estadística & datos numéricos , Fragilidad Cromosómica , Síndrome del Cromosoma X Frágil/epidemiología , Discapacidad Intelectual/epidemiología , Adolescente , Negro o Afroamericano/psicología , Población Negra/genética , Southern Blotting , Niño , Estudios Transversales , Estudios de Factibilidad , Femenino , Síndrome del Cromosoma X Frágil/diagnóstico , Síndrome del Cromosoma X Frágil/genética , Asesoramiento Genético , Pruebas Genéticas , Guadalupe/epidemiología , Humanos , Incidencia , Discapacidad Intelectual/diagnóstico , Discapacidad Intelectual/genética , Masculino , Linaje , Reacción en Cadena de la PolimerasaRESUMEN
Fragile x syndrome (FXS) is the most frequent cause of inherited mental retardation (1:1500 males, 1:2500 females) and affects all ethnic groups. Recent demonstration of an original genetic basis, involving expansion of a (CGG)n repeat in affected individuals, has allowed development of efficient, specific and sensitive laboratory procedures of DNA analysis. Diagnosis of FXS has important implications in terms of genetic counselling. We have conducted a screening survey of FXS (and FRAXE) in Guadeloupe, among 138 boys and 88 girls affected with moderate to severe mental retardation and attending special schools. Using the procedure described by Wang et al (1995), with modifications, in order to estimate prevalence of FXS among these children and compare it to prevalences observed among Caucasian populations identify FXS index cases allowing for genetic counseling for their families and evaluate systematic screening for FXS and FRAXE using DNA analysis. We found a prevalence of FXS of 5.7 percent among boys and 0 percent among girls (3.5 percent overall); none of these cases was already known. No FRAXE case was identified. These results are consistent with other similar surveys concerning Caucasian populations. This study, like others, has demonstrated the efficiency, acceptablility and usefulness on DNA analysis for FXS screening (AU)