What is genetics?
Genes and Chromosomes: The Building Blocks of Life
Every human being has approximately 30,000 genes that determine growth, development and operation of our physical and biochemical systems. Typically, genes are distributed on 46 chromosomes (23 pairs) inside our cells.
Pairs 1 through 22 are equal in men and women and are known as autosomes. The pair number 23 is composed of the chromosomes that determine sex. Females have two X chromosomes and males one X and one Y chromosome
Sperm and egg cells are different from other body cells. These reproductive cells have only 23 independent chromosomes each. When a sperm and egg combine, in early pregnancy, form a new cell with 46 chromosomes. The resulting human being is genetically unique and its design is determined by the father and mother in equal parts.
Genetics and Inherited Traits
Modern science has helped us to understand why different generations of a family have the same eye color or baldness, as well as other inherited traits, and are useful, harmless or harmful, or why sometimes occur even without background family. The genes responsible for these traits, are tiny packets of information containing instructions on how to develop and operate our bodies.
Sometimes, an abnormal gene can cause or contribute to the emergence of a birth defect. Birth defects are abnormal conditions
The structure of the body
Operation (such as fragile X syndrome, a form of mental retardation)
Chemistry of the body in which the absence of an enzyme causes mental retardation and death mainly in people of Eastern European Jewish or French Canadian)
We have identified several thousand different birth defects. They occur in one in 28 births, affecting millions of families.
Birth defects also may result from environmental factors such as drug or alcohol abuse, certain infections or exposure to certain medications or other chemicals. Often, birth defects appear to reflect a combination of heredity and environment.
The genetic counseling helps people identify and understand what particular traits can be transmitted to their children and to determine the specific risks that could influence the outcome of pregnancy.