Multifaktorielle

Multifaktorielle, also referred to as multifactorial, describes traits and diseases that arise from the combined influence of multiple genetic factors and environmental conditions. In human genetics, these traits are typically polygenic, with many genes contributing small effects, and are modulated by non-genetic influences such as nutrition, physical activity, and exposure to environmental factors.

Unlike single-gene (Mendelian) disorders, multifactorial traits show continuous variation and do not segregate in simple patterns. Family clustering occurs, but recurrence risk depends on the degree of relatedness and is not deterministic. The liability-threshold model posits an underlying, normally distributed susceptibility that, when exceeding a threshold, yields the trait.

Genetic contributions are usually additive across many loci, with environmental factors and gene–environment interactions shaping the final phenotype. Epigenetic mechanisms and developmental influences can also affect expression, leading to variable penetrance and expressivity across individuals and populations.

Common multifactorial conditions include type 2 diabetes, coronary artery disease, hypertension, obesity, neural tube defects, and cleft lip with or without cleft palate. Morphological traits such as height and complex cognitive traits also show multifactorial patterns, reflecting both genetic and environmental variation.

Clinical implications emphasize family history for risk assessment, while predictive power of genetic tests is limited for most multifactorial diseases. Prevention focuses on modifiable factors, such as diet, exercise, smoking cessation, and regular screening, alongside individualized medical guidance informed by risk estimates.