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Genetic and Rare Diseases Information Center (GARD)

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HMG CoA lyase deficiency


Other Names for this Disease
  • 3-hydroxy-3-methylglutaric aciduria
  • 3-hydroxy-3-methylglutaryl-CoA lyase deficiency
  • Defect in leucine metabolism
  • HL deficiency
  • HMG-CoA lyase deficiency
More Names
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Overview



What is HMG CoA lyase deficiency

What are the signs and symptoms of HMG CoA lyase deficiency?

How is HMG CoA lyase deficiency inherited?


What is HMG CoA lyase deficiency

HMG CoA lyase deficiency is an inherited disorder in which the body cannot process leucine or make ketones. Ketones are used for energy during periods of fasting. This condition causes episodes of vomiting, diarrhea, dehydration, extreme tiredness (lethargy), and weak muscle tone (hypotonia). During an episode, blood sugar levels can become dangerously low (hypoglycemia), and a buildup of harmful compounds can cause the blood to become too acidic (metabolic acidosis). If untreated, the disorder can lead to breathing problems, convulsions, coma, and death. Episodes are often triggered by an infection, fasting, strenuous exercise, or other types of stress. Mutations in the HMGCL gene cause HMG-CoA lyase deficiency, and this condition is inherited in an autosomal recessive pattern.[1]
Last updated: 11/24/2009

What are the signs and symptoms of HMG CoA lyase deficiency?

The signs and symptoms of HMG CoA lyase deficiency usually appear within the first year of life. The condition causes episodes of vomiting, diarrhea, dehydration, extreme tiredness (lethargy), and weak muscle tone (hypotonia). During one of these episodes, blood sugar levels can become dangerously low (hypoglycemia), and a buildup of harmful compounds can cause the blood to become too acidic (metabolic acidosis). If untreated, the disorder can lead to breathing problems, convulsions (seizures), coma, and death. Episodes are often triggered by an infection, fasting (not eating enough), strenuous exercise, or other types of stress.[2]
Last updated: 12/21/2010

How is HMG CoA lyase deficiency inherited?

HMG CoA lyase deficiency is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene (and are referred to as carriers), but they typically do not show signs and symptoms of the condition. When parents who are both carriers of an autosomal recessive condition have a child, there is a 1 in 4 (25%) chance for each child to have the condition, a 1 in 2 (50%) chance for each child to be a carrier like each of the parents, and a 1 in 4 (25%) chance for the child not to have the condition and not be a carrier.

It is possible for an individual with an autosomal recessive condition to have a child with the same condition; if an individual has the condition and the other parent is a carrier for the same condition, there would be a 1 in 2 (50% chance) for each child to have the condition and a 1 in 2 (50%) chance for the child to be a carrier (but not have the condition). However, in the case of HMG CoA lyase deficiency, it would be highly unlikely for an adult to unknowingly have it and not experience the very severe, specific signs and symptoms that typically first occur in infancy.
Last updated: 12/21/2010

References
  1. 3-hydroxy-3-methylglutaryl-coenzyme A lyase deficiency. Genetics Home Reference. October 2008; http://ghr.nlm.nih.gov/condition=3hydroxy3methylglutarylcoenzymealyasedeficiency. Accessed 11/24/2009.
  2. 3-hydroxy-3-methylglutaryl-coenzyme A lyase deficiency. Genetics Home Reference. October, 2008; http://ghr.nlm.nih.gov/condition/3-hydroxy-3-methylglutaryl-coenzyme-a-lyase-deficiency. Accessed 12/21/2010.