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Genetic linkage is the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction.Two genetic markers that are physically near to each other are unlikely to be separated onto different chromatids during chromosomal crossover, and are therefore said to be more linked than markers that are far apart.
Sex-limited genes are also distinguished from sex-influenced genes, where the same gene will show differential expression in each sex. Sex-influenced genes commonly show a dominant/recessive relationship, where the same gene will have a dominant effect in one sex and a recessive effect in the other (for example, male pattern baldness).
A disease or trait determined by a gene on the X chromosome demonstrates X-linked inheritance, which can be divided into dominant and recessive patterns.. In X-linked recessive inheritance, a son born to a carrier mother and an unaffected father has a 50% chance of being affected, while a daughter has a 50% chance of being a carrier, however a fraction of carriers may display a milder (or even ...
Sexual dimorphism was also described in the gene level and shown to extend from the sex chromosomes. Overall, about 6500 genes have been found to have sex-differential expression in at least one tissue. Many of these genes are not directly associated with reproduction, but rather linked to more general biological features.
Many of the non-sex determining X-linked genes are responsible for abnormal conditions. The Y chromosome carries about 78 genes. Most of the Y chromosome genes are involved with essential cell house-keeping activities and sperm production. Only one of the Y chromosome genes, the SRY gene, is responsible for male anatomical traits.
This is an accepted version of this page This is the latest accepted revision, reviewed on 27 February 2025. Science of genes, heredity, and variation in living organisms This article is about the general scientific term. For the scientific journal, see Genetics (journal). For a more accessible and less technical introduction to this topic, see Introduction to genetics. For the Meghan Trainor ...
X-linked recessive inheritance. X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be always expressed in males (who are necessarily hemizygous for the gene mutation because they have one X and one Y chromosome) and in females who are homozygous for the gene mutation (see zygosity).
The Y-chromosome has been entirely mapped, [7] revealing many Y-linked traits. [8] Y linkage is similar to, but different from X linkage; although, both are forms of sex linkage. X linkage can be genetically linked and sex-linked, while Y linkage can only be genetically linked. This is because males' cells have only one copy of the Y-chromosome.