One of the hereditary metabolic diseases is phenylketonuria, caused by a violation of the conversion

One of the hereditary metabolic diseases is phenylketonuria, caused by a violation of the conversion of the amino acid phenylalanine. As a result of the disease, children quickly develop dementia. The mutant gene is recessive to the normal gene. Determine the degree of risk of having a child with phenylketonuria: a) if both parents are heterozygous for this trait? b) if one parent is sick, and the other has a healthy heredity? c) is phenylketonuria related to mendelian symptoms?

Let us designate the recessive mutant gene that causes the development of phenylketonuria in humans as f, then the gene that determines the well-being in relation to this disease will be designated as F.

a) Heterozygous parents have genotypes Ff and produce spermatozoa and eggs of two types – f and F. The offspring possible for such a pair will be represented by the following options: healthy children – homozygotes (FF) – 25%; healthy children – heterozygotes (Ff) – 50%; children with phenylketonuria (ff) – 25%;

b) A parent with phenylketonuria has a genotype ff homozygous for the mutant gene and produces germ cells f. A parent with an absolutely healthy inheritance has a homozygous FF genotype for the dominant gene and produces germ cells containing an exceptionally healthy gene F. All offspring will have a heterozygous Ff genotype and will be healthy;

c) Mendelian traits are usually called those genetically determined traits, the inheritance of which is carried out according to Mendel’s laws. Since the situations discussed above correspond to these patterns, it can be concluded that phenylketonuria in humans is a mendelian trait.