What is sex-linkage?

Sex-linkage refers to the association of certain genes with the sex chromosomes, which are designated as X and Y in humans. Genes that are located on the sex chromosomes exhibit inheritance patterns that are different from those of genes located on autosomes (non-sex chromosomes).

In humans, the X chromosome carries many genes, some of which are responsible for traits or disorders that are often more prevalent in one sex than the other—most notably males, who have only one X chromosome, while females have two. This disparity leads to unique patterns of inheritance for traits linked to the X chromosome, such as color blindness and hemophilia.

Understanding sex-linkage is important in genetics as it helps explain phenomena such as the higher incidence of certain genetic disorders in males and the inheritance patterns that can occur through maternal lines. This clear differentiation is why identifying a gene located on a sex chromosome is a defining characteristic of sex-linkage.