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Diseases

Genetic and Rare Diseases Information Center (GARD)

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Pyruvate dehydrogenase deficiency


Other Names for this Disease
  • PDHC
  • Pyruvate dehydrogenase complex deficiency
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Inheritance


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How is pyruvate dehydrogenase deficiency inherited?

Pyruvate dehydrogenase deficiency is most commonly caused by mutations in the E1 alpha gene, which is located on the X chromosome (one of the sex chromosomes) and is typically inherited in an X-linked dominant manner. Dominant inheritance occurs when an abnormal gene from one parent is capable of causing disease, even though a matching gene from the other parent is normal. The abnormal gene "dominates" the gene pair.[1] Females have two X chromosomes (one from each parent) and males have one X chromosome from the mother and one Y chromosome from the father. For an X-linked dominant disorder, because one mutated gene is enough to cause the condition, both males and females can have the condition. Because males have no other copy of the X chromosome with a working gene, affected males usually have more severe disease than affected females (who have another X chromosome with a working gene).  If the father carries the abnormal X gene, all of his daughters will inherit the disease and none of his sons will have the disease. If the mother carries the abnormal X gene, there is a 50% (1 in 2) chance for each child (whether male or female) to inherit the disease.[1] The condition may also be caused by a new mutation that first appears in an affected individual, without either parent carrying an abnormal gene for the condition.

The other genes that are thought to cause pyruvate dehydrogenase deficiency appear to be inherited in an autosomal recessive manner and are not on the sex chromosomes.[2] This means that two non-working copies of the gene that is causing the condition must be present for an individual to have the condition. When an individual has an autosomal recessive condition, each of that person's parents have a non-working copy of the gene and are referred to as "carriers." When 2 carriers for the same condition are having children, there is a 25% (1 in 4) chance for each child to have the condition, a 50% (1 in 2) chance for each child to be a carrier like each of the parents, and a 25% chance for each child to not have the condition and not be a carrier.
Last updated: 1/4/2011

References
  1. Neil K. Kaneshiro. Sex-linked dominant. MedlinePlus. April 26, 2010; http://www.nlm.nih.gov/medlineplus/ency/article/002050.htm. Accessed 1/3/2011.
  2. Richard E Frye, Paul J Benke. Pyruvate dehydrogenase complex deficiency. eMedicine. November 6, 2009; http://emedicine.medscape.com/article/948360-overview. Accessed 1/3/2011.