Abstract
BackgroundMultiple Acyl-CoA-Dehydrogenase deficiency (MADD) is an inherited metabolic disorder characterized by impaired oxidation of fatty acids and some amino acids.MethodsWe were interested whether children with MADD could tolerate a prolonged low-intensity exercise test and if this test could have any additional diagnostic value. Therefore, we performed a maximal exercise test and a low-intensity prolonged exercise test in 2 patients with MADD and in 5 control subjects. During a prolonged exercise test the subjects exercised on a cycle ergometer at a constant workload of 30% of their maximum for 90 minutes and heart rate, oxygen uptake, fuel utilization and changes in relevant blood and urinary parameters were monitored.ResultsThe tests were tolerated well. During the prolonged exercise test the fatty acid oxidation (FAO) was quite low compared to 5 control subjects, while characteristic metabolites of MADD appeared in plasma and urine.ConclusionWe suggest that the prolonged exercise test could be of diagnostic importance and might replace the fasting test as a diagnostic procedure in some cases, particularly in patients with anamnestic signs of intolerance for prolonged exercise.
Highlights
Multiple Acyl-CoA-Dehydrogenase deficiency or Glutaric Acidemia Type II (MADD; McKusick # 231680) is an inborn error due to a deficiency of electron transfer flavoprotein (ETF) or of ETF-ubiquinone oxidoreductase, and is characterized by impaired oxidation of fatty acids (FAO) and some amino acids
During the test the subjects breathed through a facemask (Hans Rudolph Inc., Kansas City, MO) connected to a calibrated respiratory gas analysis system (Oxycon Champion, Jaeger, Bilthoven, The Netherlands) which measured and or calculated breath-bybreath minute ventilation (VE), oxygen uptake (VO2), carbon dioxide production (VCO2), and respiratory exchange ratio (RER; = VCO2·VO2-1) using conventional equations
Both children had normal quadriceps muscle strength. Both children met the criteria for a maximal exercise test, i.e. a Heart rate (HR) > 180·min-1, RER > 1.0 and increased blood lactate concentrations
Summary
Multiple Acyl-CoA-Dehydrogenase deficiency or Glutaric Acidemia Type II (MADD; McKusick # 231680) is an inborn error due to a deficiency of electron transfer flavoprotein (ETF) or of ETF-ubiquinone oxidoreductase, and is characterized by impaired oxidation of fatty acids (FAO) and some amino acids. Patients with milder forms of the disorder present with a variety of symptoms such as hypoglycemia, Reye-like episodes, intermittent vomiting, acidosis and myopathy [1]. In patients with metabolic diseases, such as glycogen storage diseases [2,3,4], and FAO disorders such as carnitine palmitoyltransferase II deficiency and very longchain acyl-coA-dehydrogenase deficiency [5,6] prolonged (page number not for citation purposes). Multiple Acyl-CoA-Dehydrogenase deficiency (MADD) is an inherited metabolic disorder characterized by impaired oxidation of fatty acids and some amino acids
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