yksittäisgeenisiin

Yksittäisgeeninen, often translated as monogenic, refers to a characteristic, trait, or disease caused by a mutation in a single gene. This contrasts with polygenic traits, which are influenced by multiple genes, and multifactorial conditions, which involve the interaction of multiple genes and environmental factors.

In monogenic inheritance, a single gene locus is responsible for the observed phenotype. The inheritance patterns of monogenic traits follow predictable Mendelian laws. These patterns can be autosomal dominant, autosomal recessive, X-linked dominant, or X-linked recessive, depending on the gene's location on an autosome or sex chromosome and the nature of the mutation. Autosomal dominant traits are expressed when only one copy of the mutated gene is present. Autosomal recessive traits require two copies of the mutated gene for the trait to manifest. X-linked inheritance patterns differ between males and females due to the presence of two X chromosomes in females and one X and one Y chromosome in males.

Examples of monogenic diseases include cystic fibrosis, Huntington's disease, sickle cell anemia, and Tay-Sachs disease. While the underlying cause is a single gene defect, the expression and severity of monogenic conditions can sometimes be modified by other genes or environmental influences, a phenomenon known as genetic or phenotypical heterogeneity. Understanding monogenic inheritance is crucial for genetic counseling, diagnosis, and the development of targeted therapies.