Screening for the fragile X syndrome among the mentally retarded: a clinical study
- Bert B A de Vriesa,
- Serieta Mohkamsinga,
- Ans M W van den Ouwelanda,
- Esther Mola,
- Kirsten Gelsemaa,
- Monique van Rijna,
- Aad Tibbena,b,
- Dicky J J Halleya,
- Hugo J Duivenvoordenb,
- Ben A Oostraa,
- Martinus F Niermeijer for the Collaborative Fragile X Study Groupa
- aDepartment of Clinical Genetics, University Hospital Dijkzigt, Erasmus University, PO Box 1738, 3000 DR Rotterdam, The Netherlands, bDepartment of Medical Psychology and Psychotherapy, University Hospital Dijkzigt, Erasmus University, Rotterdam, The Netherlands
- Dr de Vries.
- Received 11 May 1998
- Revised 27 January 1999
Abstract
The fragile X syndrome is characterised by mental retardation with other features such as a long face with large, protruding ears, macro-orchidism, and eye gaze avoidance. This X linked disorder is caused by an expanded CGG repeat in the first exon of the fragile X mental retardation (FMR1) gene which is associated with shut down of transcription and absence of the fragile X mental retardation protein (FMRP). Molecular testing is used for detection of patients and carriers of the fragile X syndrome.
In a screening programme for the fragile X syndrome in the south west of The Netherlands, 896 males and 685 females with an unknown cause for their mental retardation were scored on seven fragile X features. All were tested by DNA analysis and 11 new cases were diagnosed. The seven item checklist allowed exclusion from further testing in 86% of the retarded males (95% CI 0.83-0.88) without missing either any of the newly diagnosed cases or, in retrospect, any of the 50 previously diagnosed cases known to our department.
These results showed that clinical preselection for DNA testing in mentally retarded males is feasible using a simple scoring list, which will increase the efficiency of further testing eightfold.
