What are the consequences of X chromosome inactivation?
If an X-linked mutation results in the absence of a certain protein, a cell which has inactivated the wild-type, X-chromosome will experience problems from the protein absence, possibly resulting in growth disadvantage of that cell, or even cell death, which will result in selection against mutant cells.
What is the result of X inactivation?
For any given patch of fur, the inactivation of an X chromosome that carries one allele results in the fur color of the other, active allele. The process and possible outcomes of random X-chromosome inactivation in female human embryonic cells undergoing mitosis.
Which is an example of X inactivation?
A prime example of X inactivation is in the coat-color patterning of tortoiseshell or calico cats (Figure 1). In cats, the fur pigmentation gene is X-linked, and depending on which copy of the X chromosome each cell chooses to leave active, either an orange or black coat color results.
What is X inactivation in genetics?
(a) Heterozygosity: X inactivation is a random phenomenon that can involve a mutant allele containing X and a normal allele X in equal proportion in the heterozygous female.
How does X-chromosome inactivation affect the phenotype?
The occurrence of this normal process affects the phenotype seen in females carrying X-linked mutant genes or chromosome anomalies. X-chromosome inactivation is a physiological mechanism that equalizes gene-dosage effects on the sex chromosomes.
What is an example of X inactivation in cats?
A classic example of X-inactivation is seen in cats. If a female cat is heterozygous for black and tan alleles of a coat color gene found on the X, she will inactivate her two Xs (and thus, the two alleles of the coat color gene) at random in different cells during development.
What is X-linked inheritance?
X-linked inheritance means that the gene causing the trait or the disorder is located on the X chromosome. Females have two X chromosomes; males have one X and one Y. Genes on the X chromosome can be recessive or dominant.