Fragile X syndrome and deletions in FMR1: New case and review of the literature

✍ Scribed by Hammond, Lyn S.; Macias, Michelle M.; Tarleton, Jack C.; Pai, G. Shashidhar

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 68 KB
• Volume: 72
• Category: Article
• ISSN: 0148-7299
• DOI: 10.1002/(sici)1096-8628(19971112)72:4<430::aid-ajmg11>3.0.co;2-s

✦ Synopsis

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.