Überdominanz

Überdominanz is a term used in genetics to describe a specific type of gene interaction where one allele completely masks the expression of another allele, even when the second allele is present in a heterozygous state. This is a more extreme form of dominance. In standard dominance, a dominant allele will mask a recessive allele, but in Überdominanz, the dominant allele's effect is so pronounced that it entirely prevents any discernible trait from the recessive allele from appearing.

This phenomenon is distinct from simple dominance, where a heterozygous individual (carrying one dominant and one recessive allele) will display the trait associated with the dominant allele. In Überdominanz, the difference in phenotypic expression between a homozygous dominant individual and a heterozygous individual is indistinguishable, as both will exhibit the same trait, and the recessive allele's contribution is completely obscured.

Überdominanz is relatively rare compared to standard dominance. Its identification relies on careful analysis of inheritance patterns. If a trait is consistently expressed at the same level in individuals with two copies of the dominant allele and individuals with only one copy of the dominant allele, it suggests Überdominanz. Understanding Überdominanz is crucial for predicting inheritance patterns and for studying gene function and regulation. It highlights the complex ways in which alleles can interact to determine an organism's observable characteristics.