Rapid FMR1-protein analysis of fetal blood: an enhancement of prenatal diagnostics

Fragile-X syndrome, a frequent cause of inherited mental retardation, is ch aracterised in almost all cases by a COG-repeat expansion that is located w ithin the FMR-I gene and that prevents the expression of fragile-X mental r etardation protein (FMRP). We describe a test that simultaneously allows th e rapid detection of FMRP in fetal lymphocytes and distinguishes these from fetal erythrocytes. Routine molecular genetic methods fail in the rare cas es where protein expression is blocked, although there is no repeat expansi on. Furthermore, they are unsuitable in cases of advanced pregnancy. Our te st proves extremely valuable under both these circumstances.