Autosomal recessive inheritance

Autosomal recessive mechanism of disease inheritance: both parents are carriers of the defective gene . In the diagram, a healthy baby is indicated in blue (birth probability is 25%), defective gene carriers in violet (50%), and a sick child in red (25% birth rate) in red. The normal gene is marked with a blue circle and a defective gene with red.

Autosomal recessive inheritance is a type of inheritance of a trait characteristic of diploid eukaryotes controlled by recessive alleles of the autosomal gene ^[1] . For a mutation or disease with this type of inheritance to occur, a mutant allele localized in the autosome must be inherited from both parents. In other words, a mutation appears only in a homozygous state, that is, when both copies of a gene located on homologous autosomes are damaged. If the mutation is in a heterozygous state, and the normal functional allele is associated with the mutant allele, then the autosomal recessive mutation does not occur.

In all cases of autosomal recessive inheritance, if both parents carry a defective gene, then according to Mendel’s laws, the probability that children, like their parents, will be carriers of the mutant gene is 50%, the probability of having a baby without a mutation is 25%, the probability of giving birth to a patient child - 25% ^[2] . Moreover, gene diseases of this type of inheritance with the same frequency are found in both men and women ^[3] .

The basis of many inherited human diseases is this type of inheritance. For example, most lysosomal storage diseases , which include Tay-Sachs disease, Gaucher disease, Nimann-Peak disease, and others, are autosomal recessive. A disease with an autosomal recessive type of inheritance is clinically expressed only when both autosomes are defective in this gene.

The prevalence of diseases inherited by the autosomal recessive type depends on the frequency of occurrence of the recessive allele in the population . Most often, recessive hereditary diseases occur in isolated ethnic groups, as well as among the population with a high percentage of closely related marriages ^{[2] [3]} .