Autosomal dominant
It has been suggested that this article be merged into Dominance relationship. (Discuss) Proposed since July 2006. |
It has been suggested that this article be merged into Sex linkage. (Discuss) Proposed since December 2006. |
An autosomal dominant gene is one that occurs on an autosomal (non-sex determining) chromosome. As it is dominant, the phenotype it gives will be expressed even if the gene is heterozygous. This contrasts with recessive genes, which need to be homozygous to be expressed.
The chances of an autosomal dominant disorder being inherited are 50% if one parent is heterozygous for the mutant gene and the other is homozygous for the normal, or 'wild-type', gene. This is because the offspring will always inherit a normal gene from the parent carrying the wild-type genes, and will have a 50% chance of inheriting the mutant gene from the other parent. If the mutant gene is inherited, the offspring will be heterozygous for the mutant gene, and will suffer from the disorder. If the parent with the disorder is homozygous for the gene, the offspring produced from mating with an unaffected parent will always have the disorder. See Mendelian inheritance.
The term vertical transmission refers to the concept that autosomal dominant disorders are inherited through generations. This is obvious when you examine the pedigree chart of a family for a particular trait. Because males and females are equally affected, they are equally likely to have affected children.
Although the mutated gene should be present in successive generations in which there are more than one or two offspring, it may appear that a generation is skipped if there is reduced penetrance.
Examples of human autosomal dominant disorders
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- Achondroplasia
- Alexander disease
- Antithrombin deficiency
- Charcot-Marie-Tooth Syndrome
- Ectrodactyly
- Cleft Chin
- Ehlers-Danlos Syndrome
- Familial hypercholesterolemia
- Facioscapulohumeral muscular dystrophy
- Fatal Familial Insomnia
- Fibrodysplasia Ossificans Progressiva
- FOXP2 Gene
- Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu Syndrome)
- Hereditary multiple exostoses
- Hereditary spherocytosis
- Huntington's Disease
- Lactose Intolerance
- Mandibulofacial dysostosis
- Marfan Syndrome
- Neurofibromatosis
- Osteogenesis Imperfecta
- Pfeiffer syndrome
- Polycystic Kidney Disease
- Tourettes Syndrome
- Treacher Collins syndrome
- Tuberous Sclerosis
- Von Hippel-Lindau disease
- Familial adenomatous polyposis
- Noonan Syndrome