3-Hydroxy-3-methylglutaric aciduria (HMG) is a rare genetic condition resulting from a mutation (error) in a person’s DNA. HMG is an organic acid condition because it may lead to harmful amounts of certain organic acids and toxins in the body. Protein in the food we eat is broken down into amino acids, or “building blocks”. We typically eat more protein than needed; therefore we often have more amino acids than we need. Enzymes (special proteins) breakdown the extra amino acids into organic acids and ammonia and then harmless products our body can get rid of. If one of the enzymes needed is missing or not working correctly, the amino acid is not broken all the way down and organic acids builds up in our system. Although organic acids are only mild acids, both organic acids and ammonia can damage our bodies if too much builds up. In this the enzyme, HMG CoA lyase, is unable to break down the amino acid, leucine. HMG CoA lyase also makes ketone bodies from fat, which help store energy. People with HMG are unable to make ketone bodies and properly store energy.
HMG is an autosomal recessive condition. Children typically show signs between 3 months and 2 years of age. Symptoms include poor appetite, tiredness, irritability, weak muscle tone, fever, vomiting, diarrhea, low blood sugar, or behavior changes. Treatment usually includes supplements and a specific diet. Early diagnosis has shown to be effective in improving the health of individuals with HMG. Many babies are screened at birth so that treatment may begin early, however the conditions included in newborn screening vary state by state. For more information, visit Baby’s First Test. Talk with your doctor about the most current treatments. Support groups also are a good source of information. A genetic counselor will help you understand the genetics.