What is Pyruvate Carboxylase Deficiency?
Pyruvate carboxylase deficiency (PC deficiency), caused by harmful genetic changes (mutations) in the PC gene, is an inherited disease that leads to a buildup of toxic substances in the blood. This buildup 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 delay, 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 those originating from 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 in the blood.
How common is Pyruvate Carboxylase Deficiency?
The overall incidence of PC deficiency is 1 in 250,000 births. The disease rate of Type A is most frequent in the Native American population (Algonquin-speaking tribes). 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 PC 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 an individual with Pyruvate Carboxylase Deficiency?
Children with the infantile form of PC deficiency 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 are expected to live a normal lifespan with limited symptoms.