Sex-linked

Sex-linked traits are those genetic characteristics determined by genes located on sex chromosomes. In humans, these are the X and Y chromosomes. Sex-linked traits are more common in one sex than the other. They are often used to refer to X-linked traits, which are traits linked to genes on the X chromosome.

Sex Chromosomes

In humans, sex is determined by two sex chromosomes, X and Y. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The Y chromosome is much smaller than the X and carries fewer genes. As a result, any gene on the X chromosome that does not have a corresponding gene on the Y chromosome will be expressed. This is why X-linked traits are more common in males than in females.

X-linked Traits

X-linked traits are traits that are determined by genes on the X chromosome. These traits can be either dominant or recessive. Dominant X-linked traits are those that are expressed if the gene is present on one of the two X chromosomes in females or on the single X chromosome in males. Recessive X-linked traits are only expressed if the gene is present on both X chromosomes in females or on the single X chromosome in males.

Y-linked Traits

Y-linked traits are traits that are determined by genes on the Y chromosome. Because males are the only sex with a Y chromosome, Y-linked traits are only expressed in males. These traits are always expressed if the gene is present, as there is no corresponding gene on the X chromosome to mask its expression.

Examples of Sex-linked Traits

Some examples of sex-linked traits include hemophilia, color blindness, and Duchenne muscular dystrophy. These are all X-linked recessive traits, meaning they are more common in males than in females.

See Also

• Genetics
• Chromosome
• Gene
• Dominance (genetics)
• Recessive trait

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