Clinical and Laboratory Study of Methylmalonic Acidemia

Recruiting now

Conditions studied: Organic Acidemia, Methylmalonic Acidemia, Inborn Errors of Metabolism

In brief

Methylmalonic acidemia (MMA), one of the most common inborn errors of organic acid metabolism, is heterogeneous in etiology and clinical manifestations. Affected patients with cblA, cblB and mut classes of MMA are medically fragile and can suffer from complications such as metabolic stroke or infarction of the basal ganglia, pancreatitis, end stage renal failure, growth impairment, osteoporosis, and developmental delay. The frequency of these complications and their precipitants remain undefined. Furthermore, current treatment protocol outcomes have continued to demonstrate substantial morbidity and mortality in the patient population. Increasingly, solid organ transplantation (liver, and/or kidney) has been used to treat patients. Disordered transport and intracellular metabolism of vitamin B12 produces a distinct group of disorders that feature methylmalonic acidemia as well as (hyper)homocysteinemia. These conditions are named after the corresponding cellular complementation class - (cblC, cblD, cblF, cblJ and cblX) - and are also heterogenous, clinically and biochemically. The genetic disorders underlying cblE and cblG feature an isolated impairment of the activity of methionine synthase, a critical enzyme involved in the conversion of homocysteine to methionine and these disorders feature (hyper)homocysteinemia. Lastly, a group of patients can have increased methylmalonic acid and/or homocysteine in the blood or urine caused by variant(s) in recently identified (ACSF3) and unknown genes. In this protocol, we will clinically evaluate patients with methylmalonic acidemia and cobalamin metabolic defects. Routine inpatient admissions will last up to 4-5 days and involve urine collection, blood drawing, ophthalmological examination, radiological procedures, MRI/MRS, skin biopsies in some, and developmental testing. In a subset of patients who have or will receive renal, hepato- or hepato-renal transplants or have an unusual variant or clinical course and have MMA, a lumbar puncture to examine CSF metabolites will be performed. In this small group of patients, CSF metabolite monitoring may be used to adjust therapy. The study objectives will be to further delineate the spectrum of phenotypes and characterize the natural history of these enzymopathies, query for genotype/enzymatic/phenotype correlations, search for new genetic causes of methylmalonic acidemia and/or homocysteinemia, identify new disease biomarkers and define clinical outcome parameters for future clinical trials. The population will consist of participants previously evaluated at NIH, physician referrals, and families directed to the study from clinicaltrials.gov as well as the Organic Acidemia Association, Homocystinuria Network America and other national and international support groups. Most participants will be evaluated only at the NIH Clinical Center. However, if the NIH team decides that a patient under the age of 2 years is a candidate subject for this research protocol, that patient may enroll at the Children's National Medical Center (CNMC) site, pending approval by Dr Chapman, the Principal Investigator of the CNMC location Individuals may also enroll in the tissue collection only part of the study at the UPMC Children's Hospital of Pittsburgh or share medical history and clinical data via telemedicine visits remotely. Outcome measures will largely be descriptive and encompass correlations between clinical, biochemical and molecular parameters.

Key facts

Study ID: NCT00078078
Run by: National Human Genome Research Institute (NHGRI)
People needed: 2275
Starts: 2004-06-07
Last updated by the study team: 2026-07-30

Who can join

Age: 0 and older, up to 115. Sex: any. Healthy volunteers: accepted.

You may not qualify if…

The PI/AI may decline to enroll a patient for reasons such as being medically unstable, residing in a hospital, sub-optimal metabolic control or for any concerns arising after review of the laboratory and clinical data; any patient who requires dialysis once or more/week and weighs <40 kg; any patient who is being treated for an intercurrent infection with antibiotics or has evidence of an acute infection and has metabolic symptoms; any patient who does not have a regular/local metabolic, genetic or endocrine physician and/or a family physician, pediatrician, or internist; any patient who may be metabolically unstable but not acutely ill; and any patient or family who may not be able to institute recommendations for appropriate testing and care before visiting the NIH. Each family may be contacted by the NIH team prior to a pending admission to confirm that the patient is metabolically stable and ready to visit the NIH in a state of relative health, with an adequate supply of special formulas, medications, supplements, and if needed, medical equipment such as feeding pumps and replacement parts for feeding tubes. A subset of participants will be enrolled in the tissue collection part of the study only (i.e. if they are too sick to travel).
Pregnant women may be eligible to enroll in the study if they are affected with methylmalonic acidemia or a cobalamin disorder or are family members of an affected subject. Pregnant women are not excluded because it is important to learn more about the effects of these disorders in pregnant participants and the fetus. This research involves no more than minimal risk to the fetus. Affected subjects who are pregnant or become pregnant during their participation on the study will not be withdrawn, but will be excluded from some procedures until the pregnancy is concluded. Affected subjects who are pregnant may undergo procedures as part of their clinical care, including blood draws, genetic studies, and consultations, according to the clinical judgement of the clinical team. Pregnant participants will be excluded from some procedures such as stable isotope, GFR testing, and MRI until the pregnancy is concluded.
Patients with methylmalonic acidemia or cobalamin disorders of any age, sex and ethnicity, undergoing a transplantation surgery at UPMC Children s Hospital of Pittsburgh, are eligible to participate in the tissue collection arm of the study. Pregnant women will be excluded from tissue collection at the UPMC Children s Hospital of Pittsburgh.
For the healthy volunteers, eligibility criteria include individuals that are age 18 and over.
Exclusion criteria include: women who are pregnant, individuals being treated with antibiotics, individuals with kidney or liver disease, individuals on a special diet such as a high protein diet or taking protein supplements and individuals with severe claustrophobia or other anxiety disorders.

Where it is running

National Institutes of Health Clinical Center — Bethesda, Maryland, United States (enrolling)
UPMC Children's Hospital of Pittsburgh — Pittsburgh, Pennsylvania, United States (enrolling)
Children's National Medical Center — Washington D.C., District of Columbia, United States

Full record on ClinicalTrials.gov

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