Viral Illnesses and IEM. Sometimes it starts with a fever, a sniffle, or a cough. Other symptoms such as nausea, vomiting and diarrhea may also occur. Different types of viral illnesses occur throughout the year whether during the cold winter months (e.g. influenza) or the hot days of summer (enteroviruses). Although many patients may weather these illnesses well, certain high-risk groups, such as patients with IEM, are at greater risk for increased morbidity and mortality. Certain patients with IEM seem to take longer to clear infections, may become infected with unusual organisms, or may take a while to bounce back from their illnesses. Some of this may be attributed to their metabolic dysfunction, however, it should be noted that many IEM have been described as having some level of immunodeficiency.

The immune system anD IEM. IEM have been described as displaying deficiencies in immune function. For example, in organic acidemias reduced numbers of white blood cells and antibodies can be found. Since white blood cells and antibodies help the body fight off infection, patients with reductions in these critical components of the immune system may be at risk for serious infections. There are two likely mechanisms by which immune dysfunction may occur in IEM. First, enzymes deficient in IEM may also be deficient in immune cells (e.g. branched chain keto acid dehydrogenase in Maple Syrup Urine Disease (MSUD)). This may lead to a block in metabolism that is critical for immune system function. Second, toxic metabolites may build up and have damaging effects on immune system function. Toxic metabolites such as lactic acid, ammonia, and the organic acids seen in MSUD, are known to inhibit the function of immune cells. While there are at least 13 IEM that have been identified as having some form of immunodeficiency, the scope and depth of the problem is under-characterized.

Nutrition and the Immune System. The management of IEM oftentimes involves restriction of offending dietary components, such as protein, which may lead to nutritional deficiencies. Patients may display biochemical (e.g. decreased prealbumin) and physical signs of malnutrition (e.g. hair loss, poor growth). Nutrient and vitamin deficiencies may also coexist. A recent review of patients with phenylketonuria, an amino acid disorder, described suboptimal nutritional outcomes following treatment.1 Besides growth impairment, deficiencies in vitamins (B6 and B12), micronutrients (iron, zinc), essential fatty acids, and protein intake (decreased bone mass and density) were described. These nutritional deficiencies may affect immune system function.
Deficiencies in energy status, protein, vitamins and nutrients, alone or in combination, can lead to clinically significant immunodeficiencies. Nutritional deficiencies at critical periods of maturation of the immune system may hamper its development leading to an immunodeficiency.2,3 In addition to immune system development, proper nutrition is also critical for maintenance of the immune system. For example, deficiencies in various nutrients including protein, zinc, iron, vitamin A, leucine, arginine, citrulline and glutamine may affect white blood cell function. The adequacy of nutrition and immune function is highlighted in elderly populations. Elderly patients often have numerous nutritional deficiencies, which may affect their ability to produce protective antibodies after the flu shot. This reduced vaccine efficacy may be overcome by nutritional supplementation and optimization.4-6 These and numerous other studies suggest that proper nutrition is essential for immune system function.

The NIH MINI Study: Metabolism, Infection and Immunity. Since infections can trigger life-threatening acute metabolic crises in children and adults with IEM, we have decided to characterize the function of the immune system in patients with IEM. The standard of care for IEM patients is routine vaccination for childhood and seasonal illnesses. However, there have been no studies to investigate whether the response to vaccination is normal in IEM patients. Vaccination represents a challenge to the immune system and can tell us how well it may be functioning. IEM patients may have enzyme deficiencies in their immune cells, a build-up of toxic metabolites, and nutritional deficiencies, all of which may impact immune system function.

The NIH MINI Study: Metabolism Infection and Immunity in Inborn Errors of Metabolism ( is an exciting new study at the NIH Clinical Center ( The main goal of our study is to learn about the function of the immune system in metabolic disorders. The NIH MINI team is available to discuss eligibility for this protocol with anyone that may be interested in participating and welcomes all inquiries (2 years of age through adult).

For more information about the study please visit our Web site: or contact the study coordinator, Janet Shiffer, C-RNP by phone at (301) 451-9145 or by email at This email address is being protected from spambots. You need JavaScript enabled to view it..

  1. Enns GM, Koch R, Brumm V, Blakely E, Suter R, Jurecki E. Suboptimal outcomes in patients with PKU treated early with diet alone: revisiting the evidence. Mol Genet Metab. Oct-Nov 2010;101(2-3):99-109.
  2. Keusch GT. The history of nutrition: malnutrition, infection and immunity. J Nutr. Jan 2003;133(1):336S-340S.
  3. McDade TW, Beck MA, Kuzawa C, Adair LS. Prenatal undernutrition, postnatal environments, and antibody response to vaccination in adolescence. Am J Clin Nutr. Oct 2001;74(4):543-548.
  4. Girodon F, Galan P, Monget AL, et al. Impact of trace elements and vitamin supplementation on immunity and infections in institutionalized elderly patients: a randomized controlled trial. MIN. VIT. AOX. geriatric network. Arch Intern Med. Apr 12 1999;159(7):748-754.
  5. Chavance M, Herbeth B, Mikstacki T, Fournier C, Vernhes G, Janot C. Nutritional support improves antibody response to influenza virus vaccine in the elderly. Br Med J (Clin Res Ed). Nov 9 1985;291(6505):1348-1349.
  6. Wouters-Wesseling W, Rozendaal M, Snijder M, et al. Effect of a complete nutritional supplement on antibody response to influenza vaccine in elderly people. J Gerontol A Biol Sci Med Sci. Sep 2002;57(9):M563-566.

Peter J. McGuire MS, MD
National Human Genome Research Institute
National Institutes of Health
49 Convent Drive, Bldg 49
Room 4A62
Bethesda, MD 20892
Phone: 301-451-7716
Fax: 301-402-2170

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