In mammals, Y-linkage refers to when a phenotypic trait is determined by an allele (or gene) on the Y chromosome. It is also known as holandric inheritance.
The Y-chromosome is small and does not contain many genes, therefore few traits are Y-linked, and Y-linked diseases are rare. Because the only humans which have a Y chromosome are males, the genes are simply passed from father to son, with no interchromosomal genetic recombination.
Chromosome Y deletions are a frequent genetic cause of male infertility. Another example in humans of a y-linked trait was thought to be hairy ears (it may also be sex-limited).[1] However, this has been discredited[2].