Accelerated prenatal diagnosis of fragile X syndrome by polymerase chain reaction restriction fragment detection

Prenatal diagnosis of fragile X syndrome requires detection of the full FMR 1 mutation in chorionic villus or amniotic fluid cell samples. Although ana lysis of genomic DNA restriction fragment pattern is a highly reliable tech nique for identification of the full FMR1 mutation, standard Southern blot determination of this pattern requires significantly more genomic DNA than is initially available from a prenatal sample. To overcome this limitation we developed a method that determines the diagnostic pattern of genomic res triction fragments from a fraction of a prenatal specimen. The prenatal DNA sample is first, digested with EcoRI and EagI, and after agarose gel elect rophoresis, the 2- to 10-kb region of the gel is serially sectioned and amp lified by polymerase chain reaction, Analysis of prenatal samples from an u naffected male and from a full mutation male showed that this approach gene rated a diagnostic pattern comparable with a Southern blot of 100-fold more material. This innovation enables laboratories to prenatally diagnose the full FMR1 mutation sooner than standard, techniques, (C) 1999 Wiley-Liss, I nc.