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.^[1]

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.^[1]

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.

We suggest that you talk to your doctor about your concerns. If appropriate, they may recommend a referral to a genetics professional. 

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics, and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.