Practice question

Y chromosome transmission is exclusively paternal to male offspring, absent in female offspring because daughters receive paternal X. Genes located in non-recombining male-specific region of Y therefore show holandric inheritance pattern: affected father passes allele to every son, who in turn passes to all of his sons indefinitely. No females ever express trait nor transmit it. Examples include SRY sex-determining factor and some spermatogenesis genes. Such all-male paternal line pattern cannot be explained by autosomal or X-linked inheritance because daughters would be affected.