The quality or state of being composed of different, dissimilar, or diverse elements, kinds, or parts.
From Greek 'hetero-' (different) and 'geneity' (quality of being a certain kind), ultimately from 'genesis' (origin). Medieval Latin gave it formal scientific status.
Genetic heterogeneity means the same disease can be caused by mutations in completely different genes—why two kids with the same diagnosis might need totally different treatments!
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