Recently, Frye (2012) has noted the existence of 6 mitochondrial genes that lie slightly proximal to the SHANK3 gene within the 22q13 region. These include genes important electron transport change function (SCO2, NDUFA6), mitochondrial DNA (TYMP) and RNA (TRMU) metabolism, fatty acid metabolism (CPT1B) and tricarboxylic acid cycle function (ACO2). Since most Individuals with PMS have deletions that include chromosomal deletion outside of the SHANK3 region, it is very likely that many, if not most, of children with PMS may have deletions in these mitochondrial genes. Many of these genes have been linked to mitochondrial disease, even in the heterozygous state. Even if recognized, mitochondrial disease is only linked to a homozygous abnormal state (autosomal recessive), the loss of one gene (heterozygous state) could result in symptomatology when associated with deletions in other mitochondrial or non-mitochondrial genes. Abnormalities in mitochondrial pathways can result in neurologic and non-neurologic symptoms including those sometimes seen in children with PMS. Added with the SHANK3 deletion, abnormalities in these mitochondrial genes could explain variations in patterns of development and the eventual cognitive potential.