This study will evaluate patients with methylmalonic acidemia (MMA) and cobalamin disorders to learn more about the genetic causes of these inherited metabolic disorders and the medical complications associated with them. People with MMA may have difficulty with growth and development, neurological problems such as strokes, seizures and low muscle tone, kidney problems, poor vision, and metabolic instability causing them to become seriously ill, sometimes with little warning. There is no cure for any genetic MMA syndrome, but special diets, medication and vitamin therapies are used for treatment.
New information, treatments and in the future, a cure, for methylmalonic acidemia will only come from patients with MMA and their families working together with doctors. Animal models of the disease (like mice) are helpful up to a point. But there is no replacement for studying the disorder in a human being.
The study seeks to learn more about the genetic causes of the various types of these inherited metabolic disorders and the medical complications associated with them by clinically evaluating patients with methymalonic acidemia and cobalamin (vitamin B12) metabolic defects. By better understanding the complications, we may gain insight into what causes them. This knowledge may help guide the development of new therapies and provide more precise ways to assess how effective current medical regimens are working.
There are some reasons that may prevent you from joining the study. Patients will be excluded if they cannot travel to the NIH because of their medical condition or are less than 2 years of age. Other criteria that may lead to exclusion include: sub-optimal metabolic control as determined by Dr. Venditti's review of the laboratory data; residing in a hospital; any patient who requires dialysis once or more/week and weighs less than 40 kg; any patient who is being treated for an intercurrent infection with antibiotics or has evidence of an acute infection; and any patient who does not have a regular/local metabolic, genetic or endocrine physician and/or a family physician, pediatrician or internist.
In this study, we will clinically evaluate patients with methymalonic acidemia and cobalamin (vitamin B12) metabolic defects. We will define and characterize a patient population, obtain cells and urine, perform mutation analysis in known genes, and search for the causative genes when the molecular basis of the complementation class is uncertain.
Routine admissions will last 4 to 5 days and occur every year. Some patients may be seen on the outpatient clinic but most will be inpatient admissions. Evaluations will involve urine collection, blood drawing, ophthalmologic examination, radiological procedures such as abdominal ultrasound and brain MRI, and developmental and neurological testing. A skin biopsy will be only performed if it has not been done or there is a need for a repeat study. In a subset of patients who have or will receive kidney, liver or liver kidney transplants or have an unusual variant or clinical course, a lumbar puncture to examine CSF metabolites will be recommended. In this small group of patients, CSF metabolite monitoring may be used to adjust MMA therapy. All testing is optional for the participants.
The visits and all testing are free and there is no cost to you, your family or your insurance company for this study.
We will pay for most of your travel expenses. If you live locally (near the NIH) we will give you some money for meals and provide lodging if necessary. If you live further away, we will pay for your transportation to NIH (plane, car mileage, train, etc), lodging, and give you some money for meals. Travel must be arranged by NIH.
No, participants in the study do not receive any compensation other than travel and lodging expenses.
Last Reviewed: April 20, 2012