Pediatric Medical Genetics - S.I. Smiian 2003

General Principles of Medical Genetics
Medical Genetic Counseling

Despite significant progress in the Prevention and Treatment of Hereditary disorders, a radical cure for this pathology does not yet exist at the present stage. Management primarily relies on symptomatic and corrective treatments to reduce the phenotypic manifestations of the disease. Currently, the main approach to preventing hereditary disorders is Medical-Genetic Counseling for families burdened by hereditary conditions.

The primary objective of medical-genetic counseling (MGC) is to prevent the birth of an affected child. This applies first and foremost to Hereditary diseases accompanied by physical and mental developmental delays, as well as severe birth defects.

Indications for medical-genetic counseling include: having a child with a congenital pathology in the family, the presence of a congenital disease in one of the parents, a history of congenital pathology among relatives, Infertility, and recurrent Pregnancy loss.

Medical-genetic counseling helps individuals with marriage and reproductive planning, provides guidance to pregnant women, assists with hereditary issues and child adoption, and ensures precise Diagnosis of hereditary diseases.

After calculating the probability of having an affected child, the medical geneticist provides advice to the family. However, the final decision regarding childbearing rests solely with the prospective parents.

Counseling consists of several stages to enable the geneticist to provide evidence-based recommendations and help the family make an informed decision. Along the way, the counselor faces not only medical challenges but also moral and ethical dilemmas.

The First stage of counseling begins with establishing a precise diagnosis. The starting point is the clinical diagnosis of the affected child. Subsequently, all Methods of Medical genetics are applied to determine the definitive diagnosis and the mode of inheritance.

The Second Stage of counseling involves assessing the risk of having an affected child. The foundation for this is the pedigree of the affected child.

Geneticists do not have a complete consensus on risk assessment. However, high risk can be considered to span the entire probability range for monogenic traits, from 1 (100% probability) down to 1/8 (12% probability of having an affected child).

Sometimes the risk of having an affected child, although present, is negligibly small—meaning it is comparable to the Background probability of any child in the general population being stillborn or inheriting semi-lethal or lethal factors. Renowned experts in genetic counseling Stevenson and Davison consider a probability threshold of 1/50 (a 2% risk) to be the cutoff. At this risk level, the physician should encourage the family to have children.

Between the zones of high and negligibly low probabilities lies a wide intermediate range where providing precise advice is challenging.

The Third Stage of counseling involves preparing a formal Conclusion regarding the risk of disease in future children and providing recommendations to the parents.

When formulating recommendations, the physician must consider the severity of the familial pathology, the magnitude of the risk of having an affected child, and the moral and ethical aspects of the situation.

The magnitude of the risk is not the sole determining factor. Even with a high probability of having an affected child, many Hereditary diseases and anomalies do not constitute a contraindication to childbearing. This applies to all hereditary defects that do not impair health. For example, refractive errors and Color Vision deficiencies do not lead to a child's disability. The same applies to conditions amenable to correction and those manifesting later in life, such as late-onset forms of diabetes, atherosclerosis, and others.

Reproductive recommendations are of paramount importance in cases such as sublethal and lethal genetic diseases, severe incurable autosomal and sex-linked dominant and recessive disorders, chromosomal abnormalities, mental illnesses, and consanguineous marriages. In such cases, The Role of the medical geneticist is most critical.

The final stage of counseling consists of helping parents make the right decision. It requires the utmost care and sensitivity.

The risk should be explained in an accessible manner, tailored to the intellectual level and educational background of those being counseled.

Passive and active forms of medical-genetic counseling are distinguished. In passive counseling, the geneticist advises individuals who independently seek consultation. The physician's role in patient recruitment is passive. Foreign countries limit themselves to this form of consultation due to the commercial nature of their healthcare systems. A large number of individuals who would benefit from MGC remain outside The Scope of screening. The active form of MGC aligns with the preventive focus of our country's healthcare system. Medical and preventive institutions identify individuals who need counseling and refer them to MGC.

The primary subjects of active counseling should be the healthy relatives of patients with hereditary pathologies. This addresses two key objectives: prognostic counseling for their offspring and screening for predispositions to familial pathology among all family members.

Combating the manifestations of hereditary anomalies—effectively correcting the phenotype—is already a reality. It is essential to remember that with early detection of a genetic defect, accurate diagnosis, and timely treatment, complete normalization of a child's development can be achieved in A number of cases. To this end, Methods for the early diagnosis of hereditary diseases are being introduced into practice. A simple diagnostic test for phenylketonuria in newborns is already in use. A number of other inherited Metabolic Disorders (such as alactasia and galactosemia) are being actively treated.

Different people possess different genotypes and, consequently, varying aptitudes for diverse activities in technology, exact sciences, and the arts. These talents often remain undiscovered, representing a significant loss for both the individual and society. Therefore, the task of geneticists is to help everyone timely identify their abilities and rationally develop and utilize them.

Possible recommendations from medical-genetic counseling:

1. Avoid consanguineous marriages.

2. Prevention of childbearing in carriers of Genetic Disorders, opting against having children.

3. Artificial Insemination.

4. Child adoption.

5. Accounting for the risk of hereditary pathology within the family.

Ways to improve heredity include searching for methods to detect and replace pathological genes (Introduction/32.html">Genetic Engineering), prohibiting consanguineous marriages, population mixing, identifying recessive carriers and providing them with treatment.

People have learned to modify their phenotype. Straight Hair can be made wavy; dark hair can be dyed blonde; speech defects caused by a cleft lip can be corrected surgically; and genes predisposing to tuberculosis can be neutralized through vaccination. Therefore, pessimism regarding the future of humankind is unjustified. However, it is still premature to speak of the possibility of radically correcting genotype pathology.

From a social perspective, the ultimate goal of genetic counseling is to reduce the frequency of pathological genes in the population, whereas the goal of an individual consultation is to help a family make informed reproductive decisions. Thus, the criterion for the effectiveness of medical-genetic counseling as a whole is the reduction of pathological Gene frequency, while the criterion for an individual consultation is A change in The behavior of those who sought advice.

For an individual consultation to be effective (useful), a crucial intermediate factor is the degree to which the provided information is understood. Social studies have shown that individuals who visit a genetic counseling clinic misunderstand or only partially comprehend the information given. Even with satisfactory counseling outcomes, about 20% of families fail to follow the geneticist's recommendations. Among families advised to proceed with childbearing, every 10th family abandoned further family planning, while among those advised to refrain from having children, every 3rd family ignored this advice.