For this systematic review and meta-analysis, we considered all studies that examined familial loading thorough family aggregation rates and/or twin resemblance up to September 30, 2021. The following databases were searched: CENTRAL (Cochrane Library); MEDLINE by PubMed (US National Library of Medicine); EMBASE; BVS (Biblioteca Virtual em Saúde); and OpenGrey (for gray literature). The search strategy was designed using DeCS headings and adapted to the terms for each database indexing vocabulary thesaurus (i.e., Medical Subject Headings [MeSH] for MEDLINE). No restrictions were placed on language or date of publication. Specific details of the search strategy for each database including the uniterms used are provided in Box S1.
