Prevalence of fragile X (A) syndrome in mentally retarded children at a genetics referral centre in Delhi, India
Jain, U.; Verma, I.C.; Kapoor, A.K.
Indian Journal of Medical Research 108: 12-16
1998
ISSN/ISBN: 0019-5340 PMID: 9745213 Document Number: 492121
The usefulness of the clinical score based on Turner 5-trait scale prior to undertaking cytogenetic or molecular tests for the diagnosis of the fragile X(A) syndrome was evaluated. Mean clinical score in fragile X positive patients was significantly higher than in fragile X negative patients (7.06 +- 1.85 vs 2.98 +- 1.6, P < 0.0001). Of 1206 children with mental retardation 360 (29.8%) boys fulfilled defined clinical criteria to be screened for fragile X syndrome by chromosomal studies. Twenty three (6.38%) of them were found to be positive for fragile X syndrome using cytogenetic techniques. Molecular confirmation in 21 affected boys (two were lost to follow up) showed full mutation in 19 (5.27%). Two patients showed a normal 5.2 kb band on southern blot. This frequency (5.27%) of fragile X (A) patients among children with nonspecific mental retardation is comparable to the results of studies in the West. Routine use of the clinical score, and the selection of patients with a score gtoreq 5 for diagnostic tests would reduce the laboratory load, especially in countries with limited facilities.