FRAXE expansion is not a common etiological factor among developmentally delayed males.
Expansion of a (CGG)n trinucleotide repeat unit at FRAXE, a newly defined fragile site distal to FRAXA, at Xq28, is reported to be associated with mild mental retardation. Three hundred developmentally delayed male patients referred for fragile X testing but negative for the FMR-1 gene trinucleotide expansion were screened for the FRAXE expansion. This group of patients had a wide range of intellectual or behavioral problems and included 19 patients who had low-level fragile site expression detected cytogenetically at Xq27-q28. None of the patients tested positive for the FRAXE expansion. These results suggest that FRAXE is not a common etiological factor among this group of patients. The data support the hypothesis that FRAXE is either very rare or a benign fragile site that is not associated with any clinical phenotype, similar to the FRAXF and FRA16A sites.
Allingham-Hawkins
D J
DJ
Department of Genetics, The Hospital for Sick Children, Toronto, Ontario, Canada.
Ray
P N
PN
D001483:Base Sequence; D002675:Child, Preschool; D002658:Developmental Disabilities / Q000235:genetics*; D005600:Fragile X Syndrome / Q000235:genetics*; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012091:Repetitive Sequences, Nucleic Acid; D014960:X Chromosome