Imprinting Disorders include Prader-Willi Syndrome and Angelman Syndrome, congenital diseases affecting expression of genes on chromosome 15.

Prader-Willi Syndrome occurs when the maternal gene is imprinted (and hence silent) and the paternal gene is mutated/deleted. Prader-Willi Syndrome classically presents with hyperphagia and hypoplastic/undescended testicles.

Angelman Syndrome occurs when the paternal gene is imprinted and the maternal gene is mutated/deleted, and presents with inappropriate laughter ("happy puppet syndrome") and severe cognitive disability.

Find Prader-Willi, Angelman Syndrome, and more Chromosomal Abnormalities among Pixorize's visual mnemonics for the USMLE Step 1 and NBME Shelf Exams.