Organic Acid Disorders

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Disease Name 3-hydroxy-3-methylglutaryl-CoA lyase deficiency
Alternate name(s) Hydroxymethylglutaric aciduria
Acronym HMG-CoA lyase deficiency
Disease Classification Organic Acid Disorder
Variants No
Variant name N/A
Symptom onset Infancy (6 months to 2 years)
Symptoms Persistent vomiting, lethargy, hypotonia, coma, seizures, apnea,
hepatomegaly.
Natural history without treatment Recurrent episodes of acute illness usually in response to fasting or to viral infection. Any episode can lead to death or
developmental delay if severe enough.
Natural history with treatment Normal IQ and development are possible. Severe hypoglycemic episodes may result in seizures and mental retardation.
Treatment Avoidance of fasting. Low fat, protein and high carbohydrate diet. Cornstarch supplementation. Carnitine supplementation.
Intravenous glucose to treat hypoglycemia during crisis episodes.
Other Crises consist of severe acidosis and hypoglycemia treated with IV glucose and bicarbonate administration.
Physical phenotype Possible microcephaly
Inheritance Autosomal recessive
General population incidence Rare
Ethnic differences No
Population N/A
Ethnic incidence N/A
Enzyme location Liver, fibroblasts and leukocytes
Enzyme Function Catalyzes the final step of leucine degradation and plays a role in ketone formation.
Missing Enzyme HMG CoA lyase
Metabolite changes 3-hydroxy-3-methylglutaric acid in urine, increased levels of
glutaric and adipic acids may be elevated in urine during crisis,
notable absence of ketosis.
Gene HMGCL
Gene location 1pter-p33
DNA testing available No
DNA testing detail N/A
Prenatal testing Prenatal testing has been accomplished by analysis of
metabolites in maternal urine at 23 weeks. Enzyme is active in
amniocytes and prenatal testing should be possible using this
method.
MS/MS Profile N/A
OMIM Link www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=246450
Genetests Link www.genetests.org
Support Group

Organic Acidemia Association
www.oaanews.org

Save Babies through Screening Foundation
www.savebabies.org

Genetic Alliance
www.geneticalliance.org
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