It is important that this process occurs otherwise a woman would produce twice the amount of normal X chromosome proteins. X inactivation is when one of the two X chromosomes in females is almost completely inactivated. X chromosomes in females undergo a process known as X inactivation. This mutation results in skeletal, craniofacial abnormalities, mental retardation, and short stature. One example of an X-linked trait is Coffin–Lowry syndrome, which is caused by a mutation in ribosomal protein gene. Just like X-linked inheritance, there will be a lack of male-to-male inheritance, which makes it distinguishable from autosomal traits. X-linked dominant inheritance will show the same phenotype as a heterozygote and homozygote. Men cannot be carriers for recessive X linked traits, as they only have one X chromosome, so any X linked trait inherited from the mother will show up.įemales express X-linked disorders when they are homozygous for the disorder and become carriers when they are heterozygous. Fathers only pass on their Y chromosome to their sons, so no X-linked traits will be inherited from father to son. This is because males inherit their X chromosome and all X-linked genes will be inherited from the maternal side. Recessive X-linked disorders are rarely seen in females and usually only affect males. X-linked genes just like autosomal genes have both dominant and recessive types. X-linked genes are found on the sex X chromosome. Examples of autosomal recessive disorders are albinism, cystic fibrosis. From an evolutionary perspective, a recessive disease or trait can remain hidden for several generations before displaying the phenotype. Because it takes two copies of a trait to display a trait, many people can unknowingly be carriers of a disease. The trait or gene will be located on a non-sex chromosome. For a recessive trait or disease to be displayed two copies of the trait or disorder needs to be presented. Autosomal recessive inheritance, a 25% chanceĪutosomal recessive traits is one pattern of inheritance for a trait, disease, or disorder to be passed on through families.

Human dominant traits