Sex linkage

<p>Sex linkage describes the sex-specific patterns of <a href="/facts/Heredity/t0aMmRWx">inheritance</a> and <a href="/facts/Gene_expression/alCPohLR">expression</a> when a <a href="/facts/Gene/e1swwPY6">gene</a> is present on a <a href="/facts/Sex_chromosome/PGYGkTQM">sex chromosome</a> (allosome) rather than a non-sex chromosome (<a href="/facts/Autosome/uN3B2AhI">autosome</a>).  Genes situated on the <a href="/facts/X_chromosome/hpJxhSUr">X-chromosome</a> are thus termed X-linked, and are transmitted by both males and females, while genes situated on the <a href="/facts/Y_chromosome/nBDd0Vlg">Y-chromosome</a> are termed Y-linked, and are transmitted by males only.  As human females possess two X-chromosomes and human males possess one X-chromosome and one Y-chromosome, the phenotype of a sex-linked trait can differ between males and females due to the differential number of <a href="/facts/Allele/8FxCS9KA">alleles</a> (polymorphisms) possessed for a given gene.  In humans, sex-linked patterns of inheritance are termed <a href="/facts/X-linked_recessive/HDoKvzId">X-linked recessive</a>, <a href="/facts/X-linked_dominant/RmeTdfeP">X-linked dominant</a> and <a href="/facts/Y-linked/lvAXoQYz">Y-linked</a>. The inheritance and presentation of all three differ depending on the sex of both the parent and the child. This makes sex-linked patterns of inheritance characteristically different from autosomal <a href="/facts/Dominance_and_recessiveness/DsvtPyQU">dominance and recessiveness</a>.  This article will discuss each of these patterns of inheritance, as well as diseases that commonly arise through these sex-linked patterns of inheritance.  Variation in these inheritance patterns arising from <a href="/facts/Aneuploidy/CmaGcLIY">aneuploidy</a> of sex chromosomes, sex-linkage in non-human animals, and the history of the discovery of sex-linked inheritance are briefly introduced.
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Sex linkage open-in-new

Sex linkage