The possession of four chromosomes of any one type in an otherwise diploid cell.
https://www.has-sante.fr/jcms/p_3374425/fr/syndrome-48-xxyy-et-autres-tetrasomies-ou-pentasomies-des-gonosomes-chez-le-garcon 2022 France practice guideline Chronic disease other guides Boys Handbook Diseases klinefelter syndrome tetrasomy chronic disease, nos Tetrasomy chronic disease sex chromosomes tetrasomy
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