A contiguous gene syndrome is a syndrome caused by abnormalities of 2 or more genes that are located next to each other on a chromosome. Prader-Willi Syndrome, which is caused by the microdeletion of 15q11-13, is a common example. Prader-Willi syndrome occurs when the deletion occurs on the paternal chromosome. If this deletion occurs on the maternal chromosome, it causes the Angelman syndrome. 22q11.2 deletion syndrome is a particularly well known example. WAGR syndrome (deletions of 11p13) is another example.Angelman syndrome M.D. Roy and D. Schmickel. (1986) Contiguous gene syndromes: A component of recognizable syndromes. J. Pediatr, 109: 231-241. [1]