A genetic disease is a deviation from the normal state, resulting from a change in the transcription or transmission of genetic information encoded in DNA.
If the alteration concerns information contained in the gamete, it is passed on from generation to generation. In the case of changes contained in somatic cells, diseases are not inherited, but a higher risk of a particular disease is possible.
In Poland, approximately 20 000 children are diagnosed with a genetically determined disease each year. In the case of autosomal dominant inher itance, the incidence of the disease does not depend on gender. Healthy offspring of a patient always have healthy children. The probability of passing the gene to offspring is 50%.
With regard to autosomal rec essive inheritance, the mutated recessive gene does not manifest itself in the presence of a normal dominant allele. Symptoms are manifested in both sexes and the risk of having a sick child is 25%. The probability of a healthy child being a carrier is 2:3.
X-linked diseases can be inherited as a dominant or recessive trait. In the case of dominant inheritance, both men and women show symptoms of the disease. Heterozygous women have a 50% risk of passing the gene on to their offspring. Heterozygous men pass on the mutated gene to their daughters. In recessive inheritance, only men show symptoms. Heterozygous women bear a 50% risk of passing the gene to offspring. Affected men pass the gene on to their daughters.