ABSTRACT
Not all birth defects involve chromosome defects that are visible through the microscope. More sensitive tests are required to detect gene mutations. Birth defects due to gene mutations (as opposed to chromosome mutations such as aneuploidy and polyploidy) do not involve chromosomal abnormalities in the usual sense. Birth defects due to gene mutations include enzyme deficiencies (such as Tay-Sachs disease), hemophilia, albinism, and red-green color-blindness.
