Methylmalonic Acidaemia (MMA)

Methylmalonic Acidaemia (MMA) also known as methylmalonic aciduria is a rare life-threatening genetic disorder present from birth. In MMA, the body is unable to break down 4 amino acids (methionine, threonine, isoleucine and valine) and certain fatty acids. This causes a build up of methylmalonic acid and other harmful substances in the body and can cause problems.

There are a number of different forms of MMA.

Some forms can be treated with Vitamin B12 injections and these types are called ‘B12 responsive MMA’.

Other forms of MMA cannot be treated with B12 injections alone and these types are called ‘non-B12 responsive MMA’. At present, the treatment for ‘non-B12 responsive MMA’ is a protein restricted diet for life and taking regular dietary supplements which contain amino acids, vitamins and minerals. Supplementation of L-Carnitine may be recommended. This is a natural substance that helps the body to get rid of harmful substances. Antibiotics taken by mouth may also be recommended to lower the amount of methylmalonic acid made in the intestine by naturally occuring bacteria.

During times of illness the body will break down its own tissue to provide energy (catabolism). This can be dangerous for people with MMA as levels of methionine, threonine, isoleucine and valine, and other acids will increase quickly.  Patients will have an individualised emergency plan to use when they are unwell.

At NCIMD, we have been treating patients with MMA for a number of decades and have significant experience of managing this disorder. Patients with MMA are managed by the multidisciplinary team and we liaise closely with the Metabolic Laboratory to ensure close monitoring of these patients. We follow international best practise guidelines in managing our patients with MMA.

For patient stories click here

Printable Resources

Methylmalonic Acidaemia Standard Emergency Letter

MMA Dietary Handbook
1 gram Exchange list 2023
Slightly Higher Exchange List 2023 for those on more than 7 exchanges
Super High Exchange List 2023-for those on more than 20 exchanges
Low Protein Manufactured Food List 2024
Reading food labels for other protein disorders
Reward Charts
Weaning your baby on a diet for MMA/ PA

Other resources
Maeve and Max have MMA Storybook-a colourful and informative storybook about Maeve and Max who have MMA has been developed by Jenny McNulty, Dietitian and Jill Moore, Play Specialist. This book focuses on the importance of the synthetic protein. If you would like a copy please contact us directly or ask for a copy at your next out-patient appointment. Meave and Max have MMA