A clinical checklist for fragile X syndrome: Screening of Thai boys with developmental delay of unknown cause

The aim of this study was to determine a cost-effective clinical checklist for fragile X syndrome (FXS) screening in a Thai male prediatric population with developmental delay of unknown cause. We studied 179 non-FXS male patients and 27 FXS patients from 18 families (age ≤ 15 years). A six-item clinical checklist was used including family history (FH), long and narrow face (F), prominent and large ears (E), attention deficit/hyperactivity (AH), autistic-like behavior (AT) and testicular volume (T). These were scored as 0 if absent, 1 if borderline, and 2 if present. All patients were tested by using PCR and/or southern blot for the FMR1 gene. We used a logistic regression model from a computer program to analyze the data (Stata, version 5.0). We used logistic regression with cluster in the same family (average score) to eliminate bias from the related FXS cases. We found that a five-item checklist, 2FH + F + 0.5E + 2AH + T = total score, was the best model. When we used this clinical checklist with a threshold of total score of 4, 78.7 per cent of the screened cases with total scores ≤ 4 could be eliminated as negative cases. In addition, all positive FXS cases had total scores > 4, We propose this five-item model for FXS screening in clinical pediatric practice, particularly from Asian population settings.