Inherited Metabolic Disorders:

Inherited metabolic disorders are genetic conditions that result in metabolism problems. Metabolism refers to all the chemical reactions taking place in the body to convert or use energy. In most inherited metabolic disorders, a single enzyme is either not produced by the body at all, or is produced in a form that doesn't work. The missing enzyme is like an absentee worker on the assembly line. Depending on that enzyme's job, its absence means toxic chemicals may build up, or an essential product may not be produced.

The code or blueprint to produce an enzyme is usually contained on a pair of genes. Most people with inherited metabolic disorders inherit two defective copies of the gene -- one from each parent. Both parents are "carriers" of the bad gene, meaning they carry one defective copy and one normal copy.

In the parents, the normal gene copy compensates for the bad copy. Their enzyme levels are usually adequate, so they may have no symptoms of a genetic metabolic disorder. However, the child who inherits two defective gene copies cannot produce enough effective enzymes and develops the genetic metabolic disorder. This form of genetic transmission is called autosomal recessive inheritance .The original cause of most genetic metabolic disorders is a gene mutation that occurred generations ago. The gene mutation is passed along through the generations, ensuring its preservation.

Each inherited metabolic disorder is quite rare in the general population. Considered all together, inherited metabolic disorders may affect about 1 in 1,000 to 2,500 newborns.

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