Alleles are the variations or alternatives for a gene locus, and they can be classified into two main categories. There are dominant and recessive alleles, where the latter’s effect is overridden by the former’s expression. If an organism possesses either two dominant or two recessive alleles, it is considered to be homozygous, whereas the combination is called heterozygous. Disorders can be linked with certain alleles, which can be an issue if it is dominant one or double recessive. For example, researchers sequenced the entire genome, which allowed them to find out that the occurrence rate of familial hypercholesterolemia is twice as high as previously estimated. It is also suggested that current technological advancements in sequencing can enable scientists and genetics to analyze the whole genome at once, instead of addressing every gene separately. In addition, it is important to note the fact that a certain part of the population might not show their disorder-causing alleles and simply be a carrier. This increases the risk of the next generation possessing the given disease.
The transmission of chromosomes and problem alleles, and hence the transmission of information about hereditary diseases, is possible according to several schemes such as autosomal dominant. If a child receives a strong dominant allele, then this gene will certainly appear. Thus, for example, achondroplasia is transmitted, and this disease, in which the growth of the limbs is impaired, and the bones become brittle. Autosomal recessive diseases are also inherent in this transmission pattern. The symptom appears only if the child received two weak recessive alleles from the parents. The likelihood of manifestation of the disease is lower than in the first case because the dysfunctional allele can be compensated by the normal dominant. Thus, phenylketonuria, albinism, and other diseases are inherited. In addition, there is a codominant method for transmitting genetic information. With this type of inheritance, both alleles are manifested, that is, both dominant and recessive.