a. High resolution G-banded ideograms and prometaphase chromosomes of the translocation derivatives and their normal homologs . An apparently balanced translocation t(4;15)(q27;q11) was identified with arrows indicating band location of breakpoints. b. DNA methylation analysis of CpG island of SNRPN promoter and exon 1. 1. The 174 bp PCR product is derived from the methylated maternal chromosome. 2. The 100 bp product is derived from the paternal chromosome. PWS: PWS control, Normal: normal control, and t(4;15) carrier; H2O: no template control. The t(4;15) carrier shows the normal bi-parental methylation pattern.