However, it is not possible to test for every genetic disorder or birth defect because the underlying cause is not always known. If an individual has a family history of a birth defect or genetic condition, this means that either the individual, offspring of the individual, or relative of the individual is known to have a genetic disorder or birth defect. Some birth defects and inherited diseases are caused by an underlying genetic defect. The cause can be an alteration in the number or structure of the chromosomes, or a change in a specific gene carried on the chromosomes. Chromosomes and Genes Typically, a human being has a total of 46 chromosomes in every cell of the body.
Chromosomes come in pairs.
Just as we inherit half of our chromosomes from each of our parents, we inherit half of our genes from our mother and half from our father. Dominant Inheritance of Genetic Disorders Genetic changes can sometimes be passed from generation to generation. There are specific patterns of inheritance for genetic conditions. Dominant inheritance refers to a disorder that can be passed directly from one generation to the next. The genetic change in a dominant disorder occurs in one of the two copies of a specific chromosome or gene.