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A heterozygous organism is an organism that has different alleles of the same gene. The allele is the version of the gene that is responsible for the generation of alternative values for the trait. Importantly, the gametes of a heterozygous representative may be different, i.e. they may consist of completely different genetic material.
What does the term “heterozygote” mean?
Term “heterozygota»Suggests that a given gene may exist in at least two forms. The combination Aa indicates that one allele of the gene is dominant – represented by a capital letter – over the other, which is represented by a lower case letter. That is, in the representative phenotype heterozygous it will have some advantage over the recessive allele. It is worth knowing that some genetic diseases are closely related to the presence of a recessive allele. Accordingly, they show themselves in the representatives homozygousand not in heterozygotach. However, there are also diseases conditioned by the presence of a dominant allele, and thus appear in u heterozygot and homozygot dominant, but not u homozygot recessive.
What is homozygous?
Homozygota is an organism that has the same chromosomal alleles of a given gene, for example AA or aa. Homozygoty they always produce gametes of the same type. They are the same in terms of genetic material. Homozygosity it can include one, several, or even all of the genes in the body.
What are the types of homozygotes?
Homozygoty we can divide into two types. The first is homozygota dominant. In such a case, where both alleles of a particular gene are dominant (e.g., BB), a representative may be homozygous dominant for more genes such as AABBCCDD, or quadruple homozygoty dominant. The second type is homozygota recessive. In this situation, both alleles are recessive and the representative may be homozygous recessive to more genes.
What is incomplete dominance?
The concept of incomplete dominance refers to heterozygoty i homozygoty. The former has a phenotype that is “intermediate” between homozygous dominant a homozygous recessive. An example of such a relationship can be represented by two colors of flowers. We have a white rose and a red rose. By crossing two heterozygoty, we get in: 1/4 homozygoty dominant, i.e. red flowers, 1/2 heterozygoty, i.e. pink flowers and 1/4 homozygoty recessive, i.e. white flowers.
What does heterozygote have to do with pregnancy?
When we plan or expect offspring, we start to think about genes, inheritance and, above all, keeping our child healthy. Unfortunately, various mutations may arise. One of them is the MTHFR mutation, which consequently leads to disorders of folic acid metabolism, increased homocysteine and hypercoagulability. Women need to be aware that this mutation increases the risk of neural tube development, Down syndrome and recurrent miscarriages. We can distinguish two very dangerous mutations of this gene: MTHFR C677T and MTHFRA1298C. We can analyze the variant 1298A> C of the MTHFR gene polymorphism and come to the conclusion that:
- MTHFR 1298AA homozygous means no mutation, normal result and full metabolic activity;
- heterozygous MTHFR 1298AC is a slight decrease in the activity of the MTHFR enzyme. In this case, you should monitor the level of homocysteine and take supplements containing folic acid;
- MTHFR 1298CC homozygous signals that the activity of the MTHFR enzyme is significantly reduced, in such a situation appropriate prophylaxis / treatment should be undertaken.
There are several indications that suggest performing the MTHFR gene mutation test, including family history of thromboembolism, family history of C677T / A1298C variants of the MTHFR gene, or homocysteine disorders. Also, if you have used hormonal contraception or hormone replacement therapy, it is worth having a test. Folic acid deficiency, which includes vitamin B9 and vitamin B12, and miscarriages should also prompt future mothers to take appropriate measures. When planning pregnancy, it is worth considering MTHFR gene mutation testing.
The test itself involves taking blood from a vein in the arm. Ideally, the patient should be on an empty stomach and his last meal was 8-12 hours ago. The day before the test, you should avoid heavy and fatty meals, as well as alcohol. Before the test itself, you can only drink a small amount of water. The waiting time for the results is approximately 12 days. You have to pay about PLN 300 for the examination.