What is Pyruvate Carboxylase Deficiency?
Pyruvate carboxylase (PC) deficiency is an inherited enzyme defect that leads to an accumulation of lactic acid and other metabolites in the blood. The build up of these substances can affect the nervous system and cause organ damage. There are three different forms of this condition.
Infantile Form (Type A)
The infantile form of PC deficiency presents with developmental delays, failure to thrive, low muscle tone, and seizures. The build up of lactic acid (lactic acidosis) can cause vomiting and difficulty breathing, especially after illness or periods of fasting. Type A is most common in North America, specifically in those of Native American ancestry.
Severe Neonatal Form (Type B)
The severe neonatal form of PC deficiency presents shortly after birth with low blood sugar, severe lactic acidosis, enlarged liver, seizures, low muscle tone, and abnormal movements. Type B is most common in people of European descent, especially France, England, and Germany.
Intermittent/Benign Form (Type C)
The intermittent/benign form of PC deficiency is the mildest form of the condition. Affected individuals may have normal neurologic development or mild delays and slightly increased levels of lactic acid.
How common is Pyruvate Carboxylase Deficiency?
Overall, pyruvate carboxylase deficiency is rare, with an estimated 1 new case in every 250,000 births. Type A, however, is more frequent in the Native American population (Algonquin-speaking tribes) with as many as 1 in 10 individuals carrying one mutated copy of the gene (a carrier). Type C has only been reported in a small number of individuals in general.
How is Pyruvate Carboxylase Deficiency treated?
There is no cure for pyruvate carboxylase deficiency, but management involves a high carbohydrate- high protein diet, hydration, and correction of the biochemical abnormalities via supplementation. Fasting and a high fat- low carbohydrate (ketogenic) diet should be avoided, as this can worsen symptoms.
What is the prognosis for a person with Pyruvate Carboxylase Deficiency?
Children with the infantile form generally live into early childhood, while the severe neonatal form leads to death within the first few months of life. Individuals with the intermittent/benign form would be expected to live a normal lifespan with limited symptoms.