PIK3CA and overgrowth syndrome: The genetic diagnosis of MCAP through detection of <i>PIK3CA</i> somatic mosaicism in a periodontal biopsy is unprecedented.<h4>Conclusions</h4>Considering the tissue distribution and level of somatic mosaicism for <i>PIK3CA</i> mutation, the composite embryologic origin of periodontium and its high fibroblast cell content make it an ideal target for molecular analysis in overgrowth syndromes, and multidisciplinary approach including paediatric dentists should be encouraged.