Biochemical and hormonal methods
Biochemical and hormonal methods of research allow to reveal the basic infringements of a metabolism and synthesis of various hormones, associated with hereditary diseases.
Diseases, which are based on a metabolic disorder, constitute a significant part of the hereditary pathology( phenylketonuria, galactosemia, alkaponuria, etc.).All of them, due to a genetic defect in the synthesis of a certain enzyme, lead to the accumulation of intermediate metabolic products in the patient's blood. Biochemical methods of research easily allow us to determine the content of these metabolites in the body and thereby suspect a hereditary pathology.
Clinical genetics uses the genetic polymorphism of a number of enzymes. It is known that there are different forms of the same enzyme that catalyze the same reaction, but differ in their molecular structure. Similar forms were called isoferents. The detection of several isoenzymes of the same enzyme indicates the existence of several alleles of this enzyme.
In other words, in single-valued loci of homologous chromosomes alternative states of the same gene responsible for the synthesis of this enzyme are presented. There are similar changes due to mutation. The structure of isoenzymes is genetically determined. Detection in the blood of a specific form of the isoenzyme or its absence indicates the genetic defect that underlies the disease.
A2-globulins of serum contain Haptoglobin( Hp) protein. With the help of electrophoresis it is possible to isolate several types of this protein. The most common types are Hp 1-1, Hp 2-1, Hp 2-2, differing in the electrophoretic mobility and the amount of protein components. The types of haptoglobin are genetically determined. They are encoded by a gene located on chromosome 16( 16q22).At present, the connection between various types of haptoglobin and certain forms of oncological diseases has been established.
Electrophoresis analysis of LP with the establishment of the type of DLP allows one to suspect a genetically determined defect underlying the violation of the exchange of LP and leading to the development of early atherosclerosis.
The study of hormones( 17-GPG, TSH, inhibin, free estriol, etc.) also plays an important role in the diagnosis of genetic diseases. Hereditary defects underlying the block of synthesis and metabolism of various hormones are discussed in Chapter 9 "Hormonal Research".