A deficiency in any one of the enzymes involved in pyruvate metabolism leads to one of many disorders.
Symptoms include seizures, intellectual disability, muscle weakness, and coordination problems.
Some of these disorders can be fatal.
Some specific pyruvate disorders are helped by changes in diet.
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 or code for functional RNA molecules.... read more . In many pyruvate metabolism 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. (See also Overview of Hereditary Metabolic Disorders Overview of Hereditary Metabolic Disorders 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'... read more .)
Pyruvate is a substance that is formed in the processing of carbohydrates Carbohydrates Carbohydrates, proteins, and fats are the main types of macronutrients in food (nutrients that are required daily in large quantities). They supply 90% of the dry weight of the diet and 100%... read more and proteins Proteins Carbohydrates, proteins, and fats are the main types of macronutrients in food (nutrients that are required daily in large quantities). They supply 90% of the dry weight of the diet and 100%... read more and that serves as an energy source for cells.
Problems with the breaking down (metabolizing) of pyruvate can limit a cell’s ability to produce energy and allow a buildup of a waste product called lactic acid (lactic acidosis). Many enzymes are involved in pyruvate metabolism. A hereditary deficiency in any one of these enzymes results in one of a variety of disorders, depending on which enzyme is deficient.
Symptoms of pyruvate metabolism disorders may develop any time between early infancy and late adulthood. Exercise and infections can worsen symptoms, leading to severe lactic acidosis.
These disorders are diagnosed by measuring enzyme activity in cells from the liver or skin. Genetic testing Genetic Counseling and Genetic Testing Before Pregnancy Genetic disorders are caused by abnormalities in one or more genes or chromosomes. Some genetic disorders are hereditary and others are spontaneous. Hereditary genetic disorders are passed down... read more , which is used to determine whether a couple is at increased risk of having a baby with a hereditary genetic disorder, is also available.
Pyruvate dehydrogenase complex deficiency
This disorder is caused by a lack of a group of enzymes needed to process pyruvate. This deficiency results in a variety of symptoms, ranging from mild to severe. Some newborns with this deficiency have brain malformations. Other children appear normal at birth but develop symptoms, including weak muscles, seizures Seizures in Children Seizures are a periodic disturbance of the brain’s electrical activity, resulting in some degree of temporary brain dysfunction. When older infants or young children have seizures, they often... read more , poor coordination, and a severe balance problem, later in infancy or childhood. Intellectual disability Intellectual Disability Intellectual disability is significantly below average intellectual functioning present from birth or early infancy, causing limitations in the ability to conduct normal activities of daily... read more is common.
This disorder cannot be cured, but some children are helped by a diet that is high in fat and low in carbohydrates. Children may also be given supplements of the vitamin thiamin Thiamin Deficiency Thiamin deficiency (causing beriberi and other problems) is most common among people whose diet mainly consists of white rice or highly processed carbohydrates in countries with high rates of... read more .
Absence of pyruvate carboxylase (pyruvate carboxylase deficiency)
Pyruvate carboxylase is an enzyme. A lack of this enzyme causes a very rare condition that interferes with or blocks the production of glucose from pyruvate in the body. Lactic acid and ketones build up in the blood. Often, this disease is fatal. Children who survive have seizures Seizures in Children Seizures are a periodic disturbance of the brain’s electrical activity, resulting in some degree of temporary brain dysfunction. When older infants or young children have seizures, they often... read more and severe intellectual disability Intellectual Disability Intellectual disability is significantly below average intellectual functioning present from birth or early infancy, causing limitations in the ability to conduct normal activities of daily... read more , although there are recent reports of children with milder symptoms.
There is no effective treatment for this disorder, but some children may be given supplements of biotin.
The following are some English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
National Organization for Rare Disorders (NORD): This resource provides information to parents and families about rare diseases, including a list of rare diseases, support groups, and clinical trial resources.
Genetic and Rare Diseases Information Center (GARD): This resource provides and easy to understand information about rare or genetic diseases.
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