kjønnsbundet

Kjønnsbundet is a Norwegian term that translates to "sex-linked" in English. It refers to the inheritance of a gene or trait that is located on one of the sex chromosomes, typically the X chromosome. In humans, females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).

Because males have only one X chromosome, any gene present on it will be expressed, whether it is dominant or recessive. This is different from autosomal inheritance, where a trait may be masked by a dominant allele on the other chromosome. For women, a recessive sex-linked trait will only be expressed if both of their X chromosomes carry the recessive allele. If they have one dominant and one recessive allele, they will be carriers but will not display the trait.

Many genetic conditions are sex-linked, including red-green color blindness and hemophilia. These conditions are more common in males because they only need to inherit one copy of the affected gene on their single X chromosome. Females, with two X chromosomes, can be carriers of these conditions if they have one normal copy and one affected copy of the gene, but they are less likely to exhibit the full condition. The Y chromosome is much smaller than the X chromosome and carries fewer genes, so Y-linked inheritance is rare.