Highly sensitive and rapid gene mapping using miniaturized blot hybridization: application to prenatal diagnosis

We have developed a protocol for the preparation and analysis of amniocyte DNA which permits more sensitive and more rapid antenatal detection of sickle-cell anemia (SCA) than previously has been possible. After rapid extraction of DNA from amniotic cells, only 50 ng of MstII-digested DNA need be analyzed by mini-gel electrophoresis and hybridization detection to determine reliably the fetal genotype. Under these conditions, the entire gene-mapping procedure can be performed within 5 days. When larger amounts of DNA (greater than 500 ng) are analyzed, the minimal diagnosis time is reduced to 2 days. The resolution of restriction fragments on mini-gels is comparable to that obtained with larger gels. The 1.15-kb betaA and 1.35-kb betaS MstII fragments are well separated. The technique is useful whenever rapid and sensitive analysis of genomic DNA is desired.