Sex-linked recessive

Inheritance - sex-linked recessive; Genetics - sex-linked recessive; X-linked recessive

Sex-linked diseases are passed down through families through one of the X or Y chromosomes. X and Y are sex chromosomes.

Dominant inheritance occurs when an abnormal gene from one parent causes disease, even though the matching gene from the other parent is normal. The abnormal gene dominates.

But in recessive inheritance, both matching genes must be abnormal to cause disease. If only one gene in the pair is abnormal, the disease does not occur or it is mild. Someone who has one abnormal gene (but no symptoms) is called a carrier. Carriers can pass abnormal genes to their children.

The term "sex-linked recessive" most often refers to X-linked recessive.


Genetics is the study of heredity and how traits are passed along from parents to offspring. Genes are contained within the chromosomes found within the egg and sperm. Each parent contributes one half of each pair or 23 chromosomes to their child, 22 autosomal and 1 sex chromosome. The inheritance of genetic diseases, abnormalities, or traits is described by both the type of chromosome the abnormal gene resides on (autosomal or sex chromosome), and by whether the gene itself is dominant or recessive.