Methylmalonic Acidemia

Inborn Error of Energy Metabolism

Methylmalonic acidemia (MMA) is an inherited condition caused by a faulty gene. Children with MMA lack a protein that the body needs to break down fats and cholesterol inside cells. As a result, these substances build up in cells, causing damage to the brain, liver, kidneys, and other organs that gets worse over time. Symptoms of MMA may include vomiting, “floppy” muscles, and excessive fatigue. Children with MMA do not gain weight and grow as they would be expected to.

Jerry Vockley, MD, PhD

Chief of Medical Genetics

Dr. Vockley is an international leader in treatment and research in medical genetics and the field of inborn errors of metabolism. He is also a founder of the North American Metabolic Academy.

What to Expect

If your child has been diagnosed with MMA, we want you to know that you are not alone – the Center for Rare Disease Therapy is here to help. Here’s what you can expect when you come to us for a consultation.

How quickly can we get an appointment?

At the Center for Rare Disease Therapy, a doctor specializing in genetic diseases can usually see a new patient within 1 to 2 weeks. To make an appointment, please call Jodie Vento at 412-692-7273 or send an email to

How long should we expect our first visit with the doctor to take?

You can expect your first visit to take from 4 to 6 hours. Your child will receive a complete evaluation and may be seen by several doctors and other health care professionals.

What will happen during our first visit?

Your child will receive a complete evaluation to establish or confirm a precise diagnosis and determine how much the disease has affected the child. Because we work as a team at the Center for Rare Disease Therapy, during your visit, your child may be seen by several doctors and other health care professionals, including a neurologist, a heart specialist, a surgeon, a nutritionist, a genetic counselor, a psychologist, and a specialist in child development.

We understand that the whole family is affected when a child has a rare disease. We see each family as our partner in caring for their child. We think the best approach to caring for a child with a rare disease emerges when we combine our depth of experience in rare diseases with your expertise in what’s best for your child.

We will talk with you about what we think is likely to happen with your child in the near future and about options we can suggest for treating and caring for your child. If surgery is an option, we will help you understand what the surgery entails and what you may need to do to prepare for it. We will also talk with you about what you can do at home to care for your child and improve his or her quality of life. Please feel free to ask our specialists any questions you have about your child’s disease, treating and caring for your child, or anything else that is on your mind.

By the end of your visit, you will have a care plan tailored to your child’s needs and an appointment for a follow-up visit in 3 months. You will be introduced to our clinical nurse practitioner, who is available by phone or video conference to help you with any concerns you have between now and your next appointment.

How long might we have to wait for test results?

Depending upon the types of tests that the doctors order, you can expect to receive a phone call within 2 weeks to explain test results and discuss recommended next steps. Test results are also made available on Children's patient portal, myCHP, which is provided at no cost to patients, parents, and guardians.

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Contact Us

At the Center for Rare Disease Therapy, every child diagnosed with a rare disease receives an individualized treatment plan and family-centered care.
For an appointment, consultation, or patient referral with an expert at Children’s Hospital of Pittsburgh of UPMC for a child diagnosed with MMA, please contact:
Jodie Vento, MGC, LCGC
Phone: 412-692-7273

Clinical Studies

Inborn Errors of Metabolism Registry

Inborn Errors of Metabolism Information System (IBEM-IS)

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Methylmalonic Acidemia Treatment with hLB-001 Gene Therapy: The SUNRISE Trial – Phase I/II

Study of hLB-001 Gene Therapy in Pediatric Patients with Methylmalonic Acidemia Characterized by MMUT Mutations

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Methylmalonic and Propionic Acidemias Natural History – The MaP Study

MaP: Mapping the Patient Journey in Methylmalonic and Propionic Acidemia, A Longitudinal, Exploratory, Natural History Study to Further Characterize and Describe the Signs and Symptoms of Patients with Organic Acidemias

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Propionic Acidemia & Methylmalonic Acidemia Specimen Sampling Study

A Stool and Biological Specimen Sampling Study in Subjects with Propionic or Methylmalonic Acidemia

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