Figure 5

Imprinting analysis of CYFIP1, NIPA2, GOLGA8E, and WHDC1L1. Northern blot analysis of CYFIP1 and NIPA2 in PWS class I and class II deletion patients using cultured lymphoblasts. The expression of CYFIP1(A)and NIPA2 (C) was comparable in the normal control and class II (CII) patient but lower in the class I (CI) patient which is consistent with haplodeficiency of CYFIPI in class I patients suggesting these two genes are not subject to imprinting. The expression of WHDC1L1 in (E), and GOLGA8E in (G) is also comparable to the normal control but the interpretation for WHDC1L1 and GOLGA8E related to imprinting is complicated by the presence of many highly similar copies in the 15q region (see text for detailed discussion). The results using a control GAPDH probe are shown in (B), (D), (F), and (H). RT-PCR expression analysis of the brain tissues from PWS patients is shown for CYFIP1 in (I), for NIPA2 in (J), for WHDC1L1 in (M), and for GOLGA8E in (N). Both transcripts were detectable in both patients but appear to be lower in PWS-2. The absence of SNRPN expression in both PWS cases is confirmed in (K) and (L) is a GADPH control for RNA input. The "+" indicates a PCR reaction carried out with reverse transcriptase and "-" is without reverse transciptase. The molecular defect of PWS-2 is most consistent with maternal UPD of chromosome 15 or a rare possibility of an imprinting mutation because of the maternal methylation pattern at the SNRPN CpG island, the absence of expression of SNRPN, and the failure to detect a deletion by array CGH (data not shown). This data is also consistent with a report by others [66].