Multiplex XLMR pedigrees have been reported with only one mutated patient having autism and MR: different X-located MR genes have been shown to be involved (NLGN4, MECP2, OPHN1, ZNF674 and FRAXA) which does not suggest that they could be "autism genes".
The base change is at a position where it is unlikely to affect splicing of the FMR-1 transcript and is most likely a neutral variant that has only a spurious false positive association with autism.
These results enable us to reject the hypothesis that multiplex autism arises from expansion of the (CGG)n trinucleotide repeat in FMR-1.(ABSTRACT TRUNCATED AT 250 WORDS)