Kompleksarve

Kompleksarve is a term used in some Nordic-language contexts to denote complex inheritance, referring to traits that do not follow simple Mendelian patterns. In genetics, it is commonly associated with polygenic traits and traits influenced by environmental factors, rather than a single gene.

Key features of kompleksarve include multiple genetic loci each contributing a small effect, gene–gene interactions (epistasis), and gene–environment interactions that shape the final phenotype. These traits often show incomplete penetrance, meaning not everyone carrying risk variants expresses the trait, and variable expressivity, meaning the trait can present with different severities. Pleiotropy, where one variant influences multiple traits, is also common. Distinguishing kompleksarve from monogenic inheritance can be challenging because the cumulative effect of many genes interacts with lifestyle, exposure, and demographic factors.

Examples commonly described as complex include height, blood pressure, susceptibility to type 2 diabetes, and many psychiatric or metabolic traits. In clinical and research settings, kompleksarve is often studied using approaches such as genome-wide association studies to identify numerous loci with small effects and polygenic risk scores to estimate overall genetic predisposition. Heritability estimates for complex traits depend on population and environment, and translating findings into prediction or treatment remains a focus of ongoing research.

In summary, kompleksarve highlights the coordinated influence of many genes and environment on trait variation, differing from single-gene (Mendelian) inheritance. See also polygenic trait, complex trait, and gene–environment interaction.