GENEration Hope

X-Chromosome Inactivation

X-chromosome inactivation is a normal biological process in which most cells in people with two X chromosomes silence one of their X chromosomes. This helps balance gene expression between people with different sex chromosome patterns. In X-linked conditions, the pattern of inactivation can influence symptoms because different cells may keep different X chromosomes active. Skewed inactivation means one X is active more often than the other.

Why it matters

X-chromosome inactivation can help explain why some X-linked disorders affect people differently, including differences in severity among girls and women.

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