What is the average life expectancy of an individual with methylmalonic aciduria? I understand it is a rare disease and that all cases are different. And how many cases of cobalamin C deficiency are there in the U.S.?
What is the prognosis and life expectancy for individuals with methylmalonic acidemia?
The effects of methylmalonic acidemia (MMA) vary from mild to life-threatening, and therefore the prognosis and life expectancy may differ significantly among affected individuals.
Affected individuals can die in the newborn period or during a later episode of metabolic decompensation. Despite therapeutic improvements over the past 20 years, several long-term complications remain a threat to affected individuals. Those who survive often have significant neurodevelopmental disability, although normal cognitive development can occur. Other complications that may occur include renal disease which may result in chronic renal failure; pancreatitis; cardiomyopathy; recurrent infections; and hypoglycemia.
Survival in individuals with MMA has improved over time. In individuals with methylmalonyl-CoA mutase (MCM) deficiency with no enzyme activity, survival at 1 year of age was over 90%, and at 5 years of age was over 80% in the 1990s. Studies looking at the median age of death of those with this subtype reported that 20% died at a median age of 2.2 years, and overall mortality was about 50% (median age of death 2 years). Overall mortality was reported to be 50% for the cobalamin B (cblB) subtype (median age of death 2.9 years); 40% for those with detectable but decreased MCM activity (median age of death 4.5 years); and about 5% for the cobalamin A (cblA) subtype (1 death at 14 days).
Last updated: 5/5/2016
How many people in the United States have cobalamin C deficiency?
The incidence of cobalamin C deficiency (cblC) has never been officially estimated. An article by LE Profitlich et al published in 2009 reported that from the start of expanded newborn screening in New York State in November 2004 up to 2009, 10 children were diagnosed with cblC, suggesting the statewide incidence is approximately 1 in 100,000 newborns. An article published in 2011 reported that over 300 patients with methylmalonic acidemia and homocystinuria due to cblC have been documented.
Last updated: 6/20/2012
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Profitlich LE, Kirmse B, Wasserstein MP, Diaz GA, Srivastava S. High prevalence of structural heart disease in children with cblC-type methylmalonic aciduria and homocystinuria. Mol Genet Metab. December 2009; 98(4):344-348.
Iraj Rezvani, David S. Rosenblatt. Chapter 79 - Defects in Metabolism of Amino Acids. Kliegman: Nelson Textbook of Pediatrics, 19th ed. Philadelphia, PA: Saunders, An Imprint of Elsevier; 2011;