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Overview of Hereditary Metabolic Disorders

By

Matt Demczko

, MD, Sidney Kimmel Medical College of Thomas Jefferson University

Last full review/revision Apr 2020| Content last modified Apr 2020
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Hereditary metabolic disorders are inherited genetic conditions that cause metabolism problems.

Heredity is the passing of genes from one generation to the next. Children inherit their parents' genes. Hereditary metabolic disorders develop when children inherit defective genes X-Linked Recessive Disorders Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more that control metabolism. There are different types of inherited disorders Inheritance of Single-Gene Disorders Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more . In most hereditary metabolic disorders, both parents of the affected child carry a copy of the abnormal gene. Because usually two copies of the abnormal gene are necessary for the disorder to occur, usually neither parent has the disorder. Some hereditary metabolic disorders are X-linked X-Linked Recessive Disorders Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more , which means only one copy of the abnormal gene can cause the disorder in boys.

There are hundreds of metabolic disorders and most of them are extremely rare.

Metabolism

Most of the foods and drinks people ingest are complex materials that the body must break down into simpler substances. This process may involve several steps. The simpler substances are then used as building blocks, which are assembled into the materials the body needs to sustain life. The process of creating these materials may also require several steps. The major building blocks are

Metabolism is this complicated process of breaking down and converting the substances ingested.

Metabolism is carried out by chemical substances called enzymes, which are made by cells in the body. If a genetic abnormality affects the function of an enzyme or causes it to be deficient or missing altogether, various metabolic disorders can occur. These disorders usually result from one or both of the following:

  • Inability to break down a substance that should be broken down, allowing a toxic intermediate substance to build up

  • Inability to produce some essential substance

Metabolic disorders are classified by the particular building block that is affected.

Diagnosis of Hereditary Metabolic Disorders

  • Prenatal screening tests

  • Newborn screening tests

After birth, many of these disorders are detected by routine newborn screening tests Newborn Screening Tests Many serious disorders that are not apparent at birth can nonetheless be detected by various screening tests. Early diagnosis and prompt treatment can reduce or prevent many disorders that may... read more . For a complete list of routine newborn screening tests by state, see the National Newborn Screening and Global Resource Center web site. However, newborns are not screened for many of the less common hereditary metabolic disorders, and doctors do tests for those disorders only when they suspect a problem.

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