Dominant autosomic Transmission

A genetic disease is known as of dominant autosomic transmission when

  • the abnormal Gène is on a nonsexual Chromosome (neither X, nor Y)
  • the presence of only one abnormal Gène is sufficient so that the disease exprime.
The abnormal gene is transmitted either by the father or by the mother (except of course if two people have the same genetic disease of dominant autosomic transmission)
During the gamètogenèse, the male or female cells pass from 2n Chromosome S (cell diploïde) to N Chromosome (haploid cell). The abnormal gene is thus present in half of the gamètes.
The characteristics of a genetic disease with dominant autosomic transmission are the following ones:
  • Any person reached with the one of her parents reached,
  • Any person reached has a risk of 1/2 to transmit its disease to each pregnancy,
  • the unscathed people do not transmit the disease,
  • It reaches the men as much as the women,
  • All the generations are atteintes.
But to be carrying gene inevitably does not mean to be sick, the demonstrations of a genetic disease depend on its Pénétrance and the Variabilité of its expression

General outline of the dominant autosomic transmission

In the diagrams the gamètes carrying normal gene are blue, the gamètes carrying abnormal gene are red. The sick people are red, the healthy people are violets

Union of a carrier and nona carrier

Like this diagram shows it, the risk for this couple to have a child carrying abnormal gene is of 1/2

Union of two carriers

Like the diagram below shows it, this couple has a risk of:
  • 3/4 to have a child carrying abnormal gene with a risk of 1/4 to have a carrying homozygote and a risk 1/2 to have a carrying hétérozygote,
  • 1/4 to have a child noncarrying abnormal gene.

In certain cases the fetuses or children homozygotes die either in utero or very quickly after the birth (Case of the Achondroplasie) while in other case (Chorée de Huntington) the homozygotie modifies the disease little.

General base of the genetic council in the diseases with dominant autosomic transmission

In genetics, the proposer nominates the person reached of the genetic disease from which one makes the genetic Conseil.

Relative of a proposer

Phratry of a proposer

Descent of a proposer

See too

Sources

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