Biochemical genetic testing is the study of the body's enzymes. Biochemical genetic studies may be taken from a blood, urine, spinal fluid or other tissue samples. These enzymes may be deficient or absent, unstable or have altered activity, which can lead to health problems, e.g., birth defects.
These disorders are called inborn errors of metabolism, since they are present at birth and affect the body's metabolism. Metabolism is the body converting food to energy. Anything not used for energy leaves the body as waste.
There are more than 200 human enzyme defects. Gene mutations can be more difficult to study than the enzyme causing the problem. The best approach depends on the disorder.
For example, mutations of the gene which causes Tay Sachs disease can be studied.
Although DNA mutation testing is available, the current studies do not detect all possible mutations. By performing lab tests for the deficient enzyme in Tay Sachs, more cases are discovered by DNA testing.