Detection of X chromosome aneuploidy using Southern blot analysis during routine population-based screening for fragile X syndrome.

We report herein two cases where detection of X chromosome aneuploidy (cytogenetically proved 45,X/46XX and 47,XXX) was made possible by molecular diagnosis during population-based carrier screening for Fragile X syndrome, using Southern blot analysis. This study emphasizes the value of molecular analysis for gene dosage to suggest chromosomal aneuploidy.