Fragile X syndrome and deletions in FMR1: new case and review of the literature.
The fragile X syndrome phenotype of mental retardation is almost always caused by abnormal CGG trinucleotide amplification within the FMR1 gene. Occasionally fragile X syndrome results from point mutations or deletions within or around the FMR1 locus. We have identified a mentally retarded African American male with typical fragile X phenotype and a 300-400 base pair intragenic deletion near the CGG repeat segment, present in his peripheral blood lymphocytes with no apparent mosaicism. His mother, who is not retarded, has a full FMR1 CGG expansion mutation with 700-900 repeats. A review of 23 published cases with FMR1 gene deletions shows full FMR1 mutation in the mother of only 1 other propositus, a male with FMR1 full mutation/premutation/deletion mosaicism of his cultured skin fibroblasts and peripheral blood lymphocytes. The various deletions within FMR1 and their clinical significance are reviewed.
Hammond
L S
LS
Department of Pediatrics, Medical University of South Carolina, Charleston 29425, USA.
Macias
M M
MM
Tarleton
J C
JC
Shashidhar Pai
G
G
D000293:Adolescent; D005091:Exons; D051860:Fragile X Messenger Ribonucleoprotein 1; D005600:Fragile X Syndrome / Q000235:genetics*; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000235:genetics; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics*; D010641:Phenotype; D016601:RNA-Binding Proteins; D017384:Sequence Deletion
D051860:Fragile X Messenger Ribonucleoprotein 1; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; C497683:FMR1 protein, human