Systematic screening for fragile X syndrome in a cohort of 574 mentally retarded children.
In this study, we evaluated the prevalence of the fragile X syndrome in a cohort of 574 mentally retarded children. The only inclusion criterion was the diagnosis of mental retardation according to the DSM-IIIR classification. We used a PCR-based strategy for the diagnosis of fragile X syndrome to facilitate systematic screening. This diagnostic scheme is based on an initial PCR to eliminate most fragile X-negative patients followed by Southern blotting for fragile X syndrome diagnosis. Altogether, 403 boys and 171 girls were tested. The prevalence of this genetic disorder was 1.9% (11/574) in the whole cohort and 2.5% (10/403) in boys. Only one case of fragile X syndrome was detected among the 171 girls tested (0.6%). Clinical examination, especially in the youngest children, was often unremarkable, and the only reason for suspecting fragile X syndrome was the presence of mental retardation. Thus, a systematic screening for the fragile X syndrome in mentally retarded children seems justified because of the importance of a precise diagnosis in genetic counseling.
Gérard
B
B
Laboratoire de Biochimie Génétique, Hôpital Robert Debré, Paris, France.
Le Heuzey
M F
MF
Brunie
G
G
Lewine
P
P
Saiag
M C
MC
Cacheux
V
V
Da Silva
F
F
Dugas
M
M
Mouren-Simeoni
M C
MC
Elion
J
J
Grandchamp
B
B
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D005600:Fragile X Syndrome / Q000453:epidemiology / Q000235:genetics*; D005820:Genetic Testing / Q000379:methods*; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D008297:Male; D015995:Prevalence