The number of trinucleotide repeats in the 5′ untranslated regions of the FMR1 and FMR2 genes
was determined by PCR in 254 Fragile XA-negative Javanese male children with developmental
disabilities. The distribution of FMR1 and FMR2 trinucleotide repeat alleles was found to be
significantly different in the Indonesian population with developmental disability compared to that
in developmentally disabled populations in North America and Europe (p < 0.021). Sequence
analysis was performed on the trinucleotide repeat arrays of the 27 individuals with FMR1 alleles in
the ‘grey zone’ (35–54 repeats). A repeat array structure of 9A9A6A9 was found in 16 unrelated
individuals with 36 repeats, confirming earlier observations in intellectually normal Japanese. We
propose that this FMR1 array pattern is specific for Asian populations and that Javanese and
Japanese populations arose from a single progenitor population.