Medical Genetics - V. M. Zaporozhan 2005

Congenital Malformations
The Concept of "Major" and "Minor" (Systemic) Teratogenesis

Teratogenesis is The process of forming developmental malformations caused by teratogenic factors. This phenomenon is referred to as "major" teratogenesis. However, teratogenic factors sometimes affect the embryo or fetus without causing pronounced morphological malformations, yet functional Disorders of the nervous and immune systems may still occur. This phenomenon is known as "minor" (systemic) teratogenesis.

Systemic teratogenesis can be induced by various environmental factors (radiation, exposure to chemical teratogens at doses that do not cause developmental malformations, Hypoxia, low doses of alcohol, smoking, illicit drugs, starvation, low-Cholesterol diet, etc.).

In minor teratogenesis, a special place is occupied by functional disorders of the child's Central Nervous system, manifested as congenital deviations from normal neural reactivity. The child's learning capacity may decrease down to severe mental retardation. Intelligence can remain within the normal range, but a child exposed to a teratogenic factor will be less capable than they could have been under a normal Pregnancy.

The impact of teratogenic factors on the fetal immune system manifests as an increased predisposition of the child to allergies.

Thus, reduced child intelligence, sometimes mental retardation, susceptibility to neuroses and allergies can be a consequence of exposure to low doses of teratogens during the prenatal period, which do not lead to malformations but disrupt the functioning of the nervous and immune systems. For the Prevention of "minor" teratogenesis, pregnancy planning, abandonment of harmful habits, limitation of medication use during pregnancy, prevention of hypoxia, A balanced diet, protection of pregnant women from teratogen exposure, and environmental protection measures are of great importance.