Multifaktoriella

Multifaktoriella is a term used primarily in Scandinavian languages to describe phenomena that arise from multiple etiological factors. In practice it corresponds to the English term multifactorial and is used to denote traits, diseases, or conditions that do not have a single causal factor but result from the combined influence of genetic variation, environmental exposures, lifestyle, and developmental context. The word is formed from the root multifaktor- meaning many factors, with the adjective ending -ell or -ella in Nordic languages to indicate characteristic of or relating to.

In medical genetics and epidemiology, multifaktoriella describes complex traits such as type 2 diabetes, cardiovascular disease, neural tube defects, many cancers, and several psychiatric and neurodevelopmental conditions where heritability exists but is distributed across many genes, each contributing modest effect sizes, and where environmental factors modify risk. Consequently, these traits exhibit substantial heterogeneity and often require large population studies to disentangle genetic and environmental contributions.

Research approaches include family and twin studies to estimate heritability, genome-wide association studies to identify risk variants, and models of gene–environment interaction and liability thresholds. Polygenic risk scores and epidemiological risk modeling are commonly used to assess individual risk within a multifaktoriella framework. The concept underscores the limitations of single-cause explanations and supports integrated strategies in public health and personalized medicine.

See also: multifactorial inheritance, complex trait, heritability, gene–environment interaction, polygenic risk score.