X-linked recessive disorders
Some features of X-linked recessive inheritance are:
- only males are affected
- there is no variation in expression, the disorder always follows a typical course
- heterozygous females are clinically unaffected but carry the mutant gene
- only rarely will a female manifest the signs of an X-linked disease; this is usually due to atypical lyonization, a new mutation in the other X chromosome, a carrier with Turner's syndrome, or X-autosome translocation
- milder signs of X-linked disorders may evolve in the female due to normal lyonization
Approximately 290 X-linked recessive conditions are known, the following are the most frequently encountered:
- red-green colour blindness
- non-specific X-linked mental retardation
- Duchenne muscular dystrophy
- Becker muscular dystrophy
- Haemophilia A (factor VIII)
- Haemophilia B (factor IX)
- X-linked ichythyosis
- X-linked agammaglobulinaemia
Related pages
- Adrenoleukodystrophy
- Alport's syndrome
- Becker muscular dystrophy
- Colour blindness
- Duchenne muscular dystrophy
- Glucose-6-phosphate dehydrogenase deficiency
- Haemophilia
- Idiopathic hypoparathyroidism
- Lesch-Nyhan syndrome
- Severe combined immunodeficiency disease
- X-linked ichthyosis
- Bruton's agammaglobulinaemia
- Monoamine oxidase A (MAOA) and mental illness
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