Pseudo dominance
Pseudo-dominance , also quasi-dominance , is a term from genetics that is mainly used in relation to hereditary diseases . He describes an autosomal - recessive inheritance , the phenotypically like an autosomal dominant mode of inheritance occurs.
This case occurs with a special combination of genotype and phenotype of the parents:
- One parent is genotypically homozygous for the allele responsible for the disease (a / a) and is therefore phenotypically diseased.
- The other parent is heterozygous for this allele (A / a) and therefore phenotypically healthy.
In this autosomal recessive inheritance, the probability that the trait will phenotypically reappear in the following generation is 50%.
A comparable autosomal dominant inheritance would be:
- One parent is genotypically heterozygous for the allele responsible for the disease (A / a) and is therefore phenotypically diseased.
- The other parent is homozygous for the normal allele (a / a) and is therefore phenotypically healthy.
The probability that the trait phenotypically reappears in the following generation is also 50%.
Phenotypically, the two inheritance patterns cannot be distinguished, so the recessive one is pseudo-dominant:
- One parent is sick and one is healthy.
- The probability that a descendant is also sick is 50%.
An exact assignment of the genotypes is possible with a heterozygote test .
Individual evidence
literature
- Murks; Grim; Holinski-Feder: Pocket textbook human genetics . 7th edition. Thieme-Verlag, Stuttgart 2006, ISBN 3-13-139297-5 , p. 600 .