Y linkage

Y-linkage, which can also be known as sex linkage, has to deal with traits that are located on the Y chromosome. In mammals, the Y-chromosome determines the sex of the organism. Y-linkage only deals with traits on the Y-chromosome. Organisms with two X-chromosomes cannot exhibit this type of Genetic linkage. Instead, females show sex-linkage through their X-chromosomes. The Y-chromosome is not sex determining in Drosophila species.

For a trait to exhibit Y-linkage it must follow these three requirements: the trait occurs in males only, it reoccurs in all sons of affected males, and that the daughters of affected men are not only phenotypically normal but also do not have affected offspring.

One trait that is known to be Y-linked occurs on spontaneously hypertensive rats. The trait is hypertension, which is composed of at least two loci in rats, one of which is autosomal while the other is Y-linked.

Y-linkage is very hard to determine and prove. The Y-chromosome is small and does not contain as many genes as autosomal genes or the X-chromosome. In the 1950s using human pedigrees, many genes were determined incorrectly to be Y-linked. Y-linkage has been disproved in many cases. Hairy Ears was at once thought to be Y-linked in humans, however that hypothesis has been discredited. Other genes, such as scaly skin have also been discredited

Y-Chromosome deletions are a frequent genetic cause of male infertility.

As of the year 2000, a number of genes were known to be Y-linked, including:

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