Definition

Noun: A mode of genetic inheritance where a dominant allele (gene variant) located on the X chromosome is sufficient to cause a specific trait or disorder. This pattern affects both males and females, but the inheritance dynamics differ between the sexes due to the difference in the number of X chromosomes.

Usage

This term is used in the fields of genetics, medicine, and biology to describe the transmission pattern of certain genetic conditions or traits. It specifies that the responsible gene is on the X chromosome and that only one copy of the mutated allele is needed for the trait to be expressed.

Examples

• Basic Usage:
  • Rett syndrome is a neurodevelopmental disorder caused by X-linked dominant inheritance.
  • The pedigree showed a pattern consistent with X-linked dominant inheritance, as affected fathers passed the trait to all their daughters but none of their sons.

Advanced Usage

• Genetic Counseling Context: In genetic counseling, explaining X-linked dominant inheritance is crucial for assessing recurrence risks. For example, an affected mother has a 50% chance of passing the condition to each child, regardless of sex. An affected father will pass the condition to all his daughters (who inherit his X chromosome) but to none of his sons (who inherit his Y chromosome).

Variants and Related Words

• X-linked inheritance (noun): A broader category of inheritance for genes on the X chromosome, which includes both dominant and recessive patterns.
• X-linked recessive inheritance (noun): A pattern where a recessive allele on the X chromosome causes the trait, which is much more common in males than in females.
• Autosomal dominant inheritance (noun): A pattern where a dominant allele on any chromosome other than the sex chromosomes (autosomes) causes a trait.

Synonyms

• X-linked dominant trait
• X-linked dominant disorder (when referring to a disease)
• Sex-linked dominant inheritance (a slightly less precise synonym, as "sex-linked" can sometimes refer to the Y chromosome as well)

Related Phrases / Idioms

• To follow an X-linked dominant pattern: This phrase is used to describe how a trait is passed down in a family.
  • The disease appears to follow an X-linked dominant pattern based on the family history.

Noun

1. hereditary pattern in which a dominant gene on the X chromosome causes a characteristic to be manifested in the offspring