IMPRINTING ANALYSIS OF 3 GENES IN THE PRADER-WILLI ANGELMAN REGION - SNRPN, E6-ASSOCIATED PROTEIN, AND PAR-2 (D15S225E)/

order to identify genes in the Prader - Willi/Angelman syndrome critic al region, radiolabeled cDNA probes from poly(A)(+) RNA from mouse tis sues were used to identify potential exon-containing genomic DNA fragm ents in cosmid or phage clones from appropriate yeast artificial chrom osomes, and these fragments were subsequently used to screen human cDN A libraries. A mouse brain cDNA probe was effective in detecting contr ol genes of various abundance including small nuclear ribonucleoprotei n polypeptide N (SNRPN), hypoxanthine-guanine phosphoribosyl transfera se, glyceraldehyde-3-phosphate dehydrogenase, and beta-actin. Two gene s mapping within the Angelman syndrome critical region were isolated. One gene was found to encode the E6-associated protein (E6-AP; gene sy mbol HPVE6A), a protein which interacts with the E6 protein of human p apilloma virus. The other gene is previously uncharacterized and is de signated PAR-2 (D15S225E) for Prader-Willi and Angelman region-gene 2. Imprinting analysis using reverse transcription-polymerase chain reac tion of RNA from fibroblasts and lymphoblasts of deletion Prader-Willi and Angelman patients demonstrated imprinting of SNRPN with exclusive expression from the paternal allele, but E6-AP and PAR-2 were not imp rinted in these cultured human cells. The ability to analyze for impri nting and expression of SNRPN and other genes in this region in cultur ed human cells will be a valuable tool for analyzing the molecular bas is of the Prader - Willi and Angelman syndromes, although imprinting m ay differ between cultured cells and tissues. Based on the biological information for EG-AP and on the imprinting analysis of E6-AP and PAR- 2, neither of these genes are strong candidates to be the Angelman gen e, but neither can be eliminated as possibilities with the available d ata.