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Clinical and Basic Investigations of Methylmalonic Acidemia (MMA) and Related Disorders

Diagnostic Criteria and Testing for MMA

To enroll in the study, patients must:
  • Be between 2 and 70 years of age and have a diagnosis of MMA
To participate in the study, patients will be admitted to the National Institutes of Health (NIH) Clinical Center for 4 to 5 days every year for 5 to 10 years and undergo the following tests and procedures:

  • A complete medical history, physical examination and eye examination.

  • Consultations from dentists and specialists for the nervous system, rehabilitation, digestive tract, endocrine and kidney, as needed.

  • A 24-hour urine collection to examine for methylmalonic acid, other acids, sugar and proteins to measure kidney function.

  • Blood tests to assess liver and thyroid function, blood counts and blood chemistries, methylmalonic acid levels, and for genetic tests and basic research studies.

  • In some patients, a blood test to measure growth hormone production as needed. A very small amount of blood is collected overnight (every 20 to 30 minutes from 8:00 p.m. to 8:00 a.m.) through an intravenous catheter (plastic tube placed in a vein). The total amount of blood drawn is approximately one tablespoon. Patients who have stopped growing or whose weight does not permit collection of one tablespoon of blood do not undergo this procedure.

  • Frequent blood pressure measurements, including overnight monitoring.

  • Skin biopsy for cell culture (cells to grow in the laboratory for future testing) if not already performed or if there is a need to repeat.

    • For this procedure, an area of skin is numbed with an anesthetic such as lidocaine. A 4-mm diameter circular area is then removed using a sharp punch the size of a pencil eraser and scissors. The wound is dressed and usually heals within a week.

  • Photographs of the face and body (wearing underwear) to help track growth and appearance.

  • Ultrasound of the abdomen (kidneys, liver, spleen etc).

  • Hand x-ray to determine bone age.

  • Dual energy x-ray absorptionometry (DEXA) scan to assess bone density. For the DEXA scan, the patient lies still on a table while the spine and hip are scanned using a small amount of radiation.

  • Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) of the brain. This is non-invasive but some patients may require sedation.

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Last Reviewed: April 20, 2012