Exclusion of the gastrin-releasing peptide receptor (GRPR) locus as a candidate gene for Rett syndrome

The gene for the gastrin‐releasing peptide receptor (GRPR) has been mapped to a candidate region for Rett syndrome (RTT) on the short arm of the X chromosome. The recent report of a translocation that disrupted the gene in an individual with mental retardation and autistic behavior prompted us to examine GRPR as a possible locus for RTT. Genomic polymerase chain reaction amplification of exons followed by single‐strand conformation analysis screening in 25 unrelated RTT‐affected individuals and by direct sequencing in 12 others has failed to detect any mutation. No gross structural rearrangements were found by Southern analysis of DNA from six unrelated RTT‐affected individuals. A high‐frequency biallelic polymorphism caused by two single nucleotide substitutions in exon 2 was discovered. The allele frequencies were identical in the RTT population as compared to 100 normal control X chromosomes. This polymorphism will enable future evaluation of the GRPR locus as a candidate for other X‐linked mental retardation or neurobehavioral syndromes. Am. J. Med. Genet. 78:173–175, 1998. © 1998 Wiley‐Liss, Inc.