Autosomal dominant inheritance

✔️ thumb | An example of a family tree with an autosomal dominantly inherited trait

Basic characteristics

 * refers to genes located on non-sex chromosomes – autosomes
 * we observe the transmission of a trait at a conditional dominant by an allele
 * phenotypicwise, the monitored trait is manifested both in heterozygotes' (Aa) and in dominant homozygotes' ( AA)
 * in the case of incomplete dominance, heterozygotes (Aa) have less severe phenotypic manifestations than dominant homozygotes (AA), in which the respective disease manifests itself in a very severe form
 * phenotypically healthy individuals (recessive homozygotes) do not transmit the mutation to subsequent generations

Genealogical characteristics

 * 'both sexes are affected equally often
 * typically it is vertical type of inheritance - at least one parent is affected (most often heterozygous), the disease occurs in practically every generation

Risk calculation

 * when two heterozygotes (Aa) are crossed, there is a three-quarters probability (75%) of the birth of an affected offspring (in 25% of cases, the affected individual is a dominant homozygous AA)
 * {| class="wikitable"

|- |  || A || a |- | A || AA || Aa |- | a || Aa || aa
 * }


 * when a recessive homozygote (aa) is crossed with a heterozygote (Aa) there is a half (50%') probability of the birth of an affected offspring (Aa)
 * {| class="wikitable"

|- |  || a || a |- | A || Aa || Aa |- | a || aa || aa
 * }

Deviations

 * sporadic cases - mutation de novo (new mutation) - common for example in achondroplasia
 * incomplete penetrance (the allele manifests phenotypically in fewer carriers than we would expect)
 * variable expressivity (variable degree of character manifestation)
 * a consequence of the external environment or other genes
 * late-onset disease – polycystic kidney disease, Huntington's chorea
 * mosaicism of germ cells
 * nonpaternity

Examples
EKG
 * Achondroplasia
 * Apert syndrome
 * Brachydactyly
 * Familial hypercholesterolemia - frequency in the population 1:500
 * Huntington's chorea - frequency in the population 1:10 000-20 000
 * Marfan syndrome
 * Myotonic dystrophy – myotonia, muscular dystrophy, cataract, hypogonadism, frontal baldness and changes
 * Neurofibromatosis – frequency in the population 1:3 500
 * Osteogenesis imperfecta
 * Polycystic kidney disease - adult type, frequency in the population 1:1 000
 * Polydactyly

related articles

 * Autosomal recessive inheritance
 * Gonosomal inheritance
 * Gonosomal dominant inheritance
 * Gonosomal recessive inheritance

Exercising

 * Diseases - learning about heredity