Characteristics of two cases with dup(15)(q11.2-q12): one of maternal and one of paternal origin

Purpose: The phenotype correlations for interstitial duplications that incl ude the Prader-Willi/Angelman syndrome critical region are not well establi shed. We describe two such duplication cases, one of which was of maternal origin and the other was paternal. Methods: High resolution G-banding, fluo rescence in situ hybridization (FISH) for SNRP-N and D15S10 were used for c ytogenetic analysis. Southern blot analyses based on parent of origin speci fic DNA methylation at D15S63 (PW71) locus were utilized for detection of m ethylated and unmethylated fragments. Results: The duplication was establis hed by the FISH analysis. The molecular pattern suggested a maternal origin of the duplication in patient 1 and a paternal origin in patient 2. Patien t 1 (2 years old) had developmental and speech delays with pervasive develo pmental disorder or mild autism, strabismus, and normal growth parameters w ith seizures. Patient 2 (16 years old) had global developmental delay, verb al IQ of 94, depression, obesity, food-seeking behavior, and significant be havioral problems that included self-injurious tendencies. Neither patient had significant dysmorphic features or abnormalities of internal organs. Co nclusion: The two cases suggest that some patients with 15q11.2q12 duplicat ion may have significant anomalies, and there appear to be phenotypic diffe rences between maternal and paternal transmission of the duplication.