A SINGLE-TUBE PCR TEST FOR THE DIAGNOSIS OF ANGELMAN AND PRADER-WILLI-SYNDROME BASED ON ALLELIC METHYLATION DIFFERENCES AT THE SNRPN LOCUS

The analysis of allelic methylation differences in 15q11-q13 has been established as a valid test for the Angelman and Prader-Willi syndrome s. Current tests use methylation-sensitive restriction enzymes and Sou thern blot analysis. Here we describe a single-tube PCR test. It is ba sed on sodium bisulfite treatment of DNA, which converts unmethylated, but not methylated cytosine residues to uracil, and PCR primers speci fic for the maternal and the paternal allele. The method was validated in a blinded retrospective study on 87 DNA samples from normal contro ls and patients. Prospective studies by independent laboratories will be needed before this assay can replace Southern blot analysis in rout ine diagnostic procedures.