Genetics with the Fundamentals of Selection - M.P. Myhun - 2008

Chapter VII. Human Genetics (Anthropogenetics)

7.3. Research Methods and Characteristics of Human Genetics

Anthropogenetics successfully combines both traditional and rapidly developing modern Methods. The most common approaches include:

1. The genealogical method, or pedigree analysis.

2. The sib method, including the twin method.

3. Cytogenetic method.

4. Biochemical method.

5. Molecular-genetic method.

6. Ontogenetic method.

7. Population method.

8. Biotechnological (cellular) method.

Each of these methods has its advantages and limitations. Maximum informational value is achieved by combining them. Over 1,000 human genes have already been studied in detail, their localization in specific regions of particular Chromosomes has been mapped, and the mechanisms of their involvement in The Development of various phenotypic traits have been elucidated. In accordance with Mendelian postulates, these genes include dominant, codominant, and recessive ones. Some of them exhibit incomplete dominance, complementation, and Other types of interactions known for allelic and non-allelic genes.

The Mutational Process in humans leads to The Emergence of alleles that negatively affect health. Hereditary diseases can result from Gene, chromosomal, or genomic abnormalities. Phenotypic anomalies caused by Mutations serve as marker traits in The Study of human heredity and Variability.

Genealogical analysis makes it possible to overcome the difficulties associated with the impossibility of controlled crossing and the small number of children in families. As a rule, genealogical analysis serves as the starting point for MEDICAL Genetic Counseling.

First of all, a pedigree is compiled; standard methodologies and designation terminology exist for this purpose. The individual with whom the investigation begins is called the proband, brothers and sisters are referred to as sibs and are designated as follows:

Class="center">Selection/selection.files/image030.jpg" width="444"/>

After compiling the pedigree, the actual genetic analysis begins. Its purpose is to conclude whether a trait (or disease) is genetically determined and to determine its mode of inheritance.

Depending on the localization of mutant genes (in an autosome or a sex chromosome) and the characteristics of gene interactions (dominance, recessiveness, etc.), the following Major Types of inheritance for monogenic traits (including hereditary diseases) in humans are distinguished:

1) autosomal dominant;

2) autosomal recessive;

3) autosomal codominant;

4) X-linked;

5) X-linked recessive;

6) Y-linked type;

7) cytoplasmic type.

Humans are an integral part of the biosphere and a product of its evolution; therefore, the patterns of biological processes of universal significance fully apply to humans as well.

At the same time, certain Specific features of humans as research subjects must be taken into account, necessitating non-traditional approaches and Research Methods. These characteristics, which significantly complicate genetic analysis, pertain not only to the biological sphere but also to the biosocial nature of human beings.

First and foremost, it should be noted that the primary evolutionary factor—natural selection—no longer plays as critical a role in human society as it does in populations of simpler organisms. Other FACTORS OF POPULATION dynamics, such as mutation processes, migration, and assortative mating, retain their significance for humans.

It must be considered that Human Evolution has shifted largely into the social realm, the most crucial component of which is culture.

In addition to genetic heredity, many scientists distinguish signal heredity, or cultural continuity, through which experience is transmitted from generation to generation.

Signal heredity is the ability of parents to pass on adaptive behavioral skills to their offspring.

This transmission can also occur between any individuals of the same generation and even from offspring to parents. An example of signal heredity in animals is The phenomenon of imprinting—the retention in memory of behavioral responses formed during the Cytology/cytology/16.html">Early stages of Postnatal development in vertebrates, such as birds.