Genealogical method. Studying the pedigree

The study of the genealogy is carried out by man since ancient times. In the 18-19 centuries, the analysis of human pathology (morbidity) began to be widely used. Thus, the genealogical method of investigation began to be formed . Subsequently, there was an improvement in both the line of compilation of pedigrees, and the line of searching for options for statistical analysis of available data.

The clinical genealogical method is a method for the study of pedigrees, the use of which makes it possible to trace the distribution of pathology in the family or family by specifying the type of related relations between their members.

This option is considered universal. The genealogical method is used widely in solving theoretical problems. In particular, this method of research is used when:

- establishing the character of heredity in the attribute;

- determining the type of inheritance of the disease or trait;

- evaluation of the penetrance (frequency of manifestation) of the gene;

- analysis of the mapping process (determining the position of the gene relative to others on the chromosome) and the linkage of genes;

- study of the intensity of the mutation process;

- deciphering the mechanisms on which the interaction of genes is based.

A fairly large number of genetic pathologies are known in modern medicine. That is why a program has been developed to examine each pregnant woman for six hereditary diseases. They include:

- phenylketonuria;

Down's syndrome;

- congenital hypothyroidism ;

- androgenital syndrome;

- galactosemia;

Cystic fibrosis.

The genealogical method can be in some cases the only way in which you can determine the type of inheritance of the disease in the family, find out the nature of the pathology, assess the prognosis of the disease, and make a differential diagnosis with other hereditary diseases. In addition, the use of this research option makes it possible to calculate the probability of the birth of sick children, as well as to select appropriate and appropriate measures for prenatal diagnosis, prevention, treatment, adaptation and rehabilitation.

The genealogical method involves the compilation of a genealogy and its graphic representation.

In the course of these activities, information is collected about the proband (the individual the specialist is studying) and his family. As a rule, research is conducted with the patient or carrier of the trait under study. However, the genealogical method can be used not only in medicine.

In one parent couple, children are called siblings (brothers and sisters). In the presence of only one parent - polusibsami. They can be half-bred (with a common father) or one-half (with a common mother).

As a rule, the compilation of a pedigree is carried out for the purpose of studying several (or one) diseases (signs). The amount of information may depend on the number of generations involved in it (the pedigree).

The analysis of the obtained information assumes the account of a number of features when revealing the types of inheritance.

So, for example, the autosomal dominant type indicates frequent detection of the trait in the pedigree (in almost every generation), in boys and girls alike. The presence of a trait in one of the parents contributes to its appearance in half or all of the offspring.

When composing pedigrees, each generation should be located on its horizontal or radius. The numbering of generations is carried out by Roman, and family members by Arabic numerals.

If there are several hereditary diseases in the family, unrelated to each other, for each pathology the pedigree is compiled separately.