SHANK1 and autism: As all members of the SHANK gene family appear to fulfill similar physiological roles and display considerable neuroanatomical co-expression, it is intriguing that Shank3−/− null mutant mice display social deficits and repetitive self-grooming behavior [123], while no such phenotypic changes relevant to the first and third diagnostic symptom of autism were found in Shank1−/− null mutant mice [23].