Microdeletions of PARK2 have been reported previously in seven patients with autism spectrum disorder. There are no reports of PARK2 microduplications in this population. Presented are two patients, one with deletion and the other with duplication, both with autism spectrum disorder, though their syndromic phenotypes vary. The deletion patient is cognitively normal and ectomorphic: the duplication patient is cognitively impaired, underweight and short. Further, the microduplication patient has demonstrated adverse medication reactions to psychotropic medications active in the dopamine metabolic pathway: cyclopentolate, lisdexamfetamine, methylphenidate. These patients support an association between PARK2 mutations and autism spectrum disorder and suggest that duplications may be equally causative. It is hypothesized that the disparate patient phenotypes may represent a deletion/duplication syndrome and that the adverse medication reactions may be a pharmacogenetic phenomenon. © 2011 Wiley-Liss, Inc.