Restriction digests of the clone give the following sizes (kb): BamHI--4.0; EcoRI--3.6, 0.33; NotI--2.9, 0.88; PvuII--2.6, 1.0 0.33; XhoI--4.0. Insert contains the following restriction sites (approximate kb from the 5' end): EcoRI--0.17, 0.63; PuvII--0.07. Insert can be used to probe genomic DNA digested with NotI/XbaI to detect abnormalities diagnostic for Prader-Willi syndrome and Angelman syndrome (AS). The probe detects a 4.2 kb fragment for normal maternal chromosomes, consistent with methylation of three NotI sites. An 0.9 kb fragment is detected for normal paternal chromosomes, consistent with the absence of methylation at these NotI sites. Normal individuals will show fragments of both sizes. Absence of the 0.9 kb band is indicative of PWS. Absence of the 4.2 kb band is indicative of AS. Insert contains a deletion breakpoint found in some cases of familial Prader-Willi syndrome (PWS). The insert contains most of exon alpha (nt 1-66), also corresponding to nt 10-75 of GenBank accession J04615, and a portion of the following intron. The 0.9 kb NotI fragment is derived from a 4.2 kb XbaI genomic DNA fragment which shows differential methylation at several rare restriction sites in normal maternal and paternal chromosomes. |
