X-linked dominant inheritance

X-linked dominant

X-linked dominant inheritance is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome. This type of inheritance can affect both males and females, but the patterns of inheritance and the severity of the condition can differ between the sexes.

Mechanism

In X-linked dominant inheritance, a single copy of the mutant gene on the X chromosome is sufficient to cause the disorder. Since females have two X chromosomes (XX), they have a higher chance of inheriting the disorder compared to males, who have only one X chromosome (XY). If a female inherits one mutant X chromosome, she will express the disorder. If a male inherits the mutant X chromosome, he will also express the disorder, often with more severe symptoms due to the lack of a second X chromosome to potentially counteract the effects of the mutation.

Inheritance Patterns

The inheritance patterns of X-linked dominant disorders can be summarized as follows:

• Affected males will pass the mutant gene to all of their daughters but none of their sons.
• Affected females have a 50% chance of passing the mutant gene to each of their children, regardless of sex.

Examples of X-linked Dominant Disorders

Some well-known examples of X-linked dominant disorders include:

• Rett syndrome
• Fragile X syndrome
• X-linked hypophosphatemia

Clinical Features

The clinical features of X-linked dominant disorders can vary widely depending on the specific condition. Common features may include developmental delays, intellectual disabilities, and various physical abnormalities. The severity of symptoms can also vary between males and females, with males often experiencing more severe manifestations.

Diagnosis and Management

Diagnosis of X-linked dominant disorders typically involves a combination of clinical evaluation, family history, and genetic testing. Management of these conditions is often multidisciplinary, involving specialists in genetics, neurology, and other relevant fields. Treatment is usually supportive and symptomatic, as there are currently no cures for most X-linked dominant disorders.

See Also

• Genetic inheritance
• X chromosome
• Autosomal dominant inheritance
• Autosomal recessive inheritance
• Y-linked inheritance