Sorted By Test Name - Mayo Medical Laboratories

VLCKM
60037
VIBC
89658
Clinical References: 1. Andresen BS, Olpin S, Poorthuis BJ, et al: Clear correlation of genotype
with disease phenotype in very-long-chain acyl-CoA dehydrogenase deficiency. Am J Hum Genet
1999;64:479-494 2. Liebig M, Schymik I, Mueller M, et al: Neonatal screening for very long-chain
acyl-CoA dehydrogenase deficiency: enzymatic and molecular evaluation of neonates with elevated
C14:1-carnitine levels. Pediatrics 2006;118:1065-1069
Very Long Chain Acyl-CoA Dehydrogenase Deficiency, Known
Mutation
Clinical Information: Very long chain acyl-CoA dehydrogenase (VLCAD) deficiency is an
autosomal recessive disorder of mitochondrial fatty acid beta-oxidation. Mitochondrial beta-oxidation
plays a major role in energy production and VLCAD catalyzes the first step in the breakdown of fatty
acids that are 14 to 20 carbons long. VLCAD deficiency has a reported incidence of approximately 1 in
30,000 births and has a variable age of onset that is generally classified into 3 categories. Individuals with
the early-onset type present with cardiomyopathy, hypotonia, and hepatomegaly in the first months of life;
sudden death is also frequent. Individuals with the early-childhood onset type typically present with
hypoketotic hypoglycemia and hepatomegaly without cardiomyopathy. Individuals with the late-onset
type of VLCAD deficiency generally present after childhood with intermittent rhabdomyolysis and
muscle dysfunction that often manifests as muscle cramps and exercise intolerance. Review of clinical
features and biochemical analysis via plasma acylcarnitines, plasma fatty acid profile, urine organic acids,
and fibroblast fatty acid oxidation probe studies are recommended as laboratory evaluations for VLCAD
deficiency. Plasma and urine biochemical testing are not reliable for identifying all individuals with
VLCAD deficiency or confirming carrier status, as biochemical findings may normalize during periods of
good metabolic control. It is uncertain whether skin fibroblast analysis can identify carriers of VLCAD
deficiency. The diagnosis is confirmed by molecular testing. Mutations in the ACADVL gene are
responsible for VLCAD deficiency. Most mutations are family specific with the exception of the V283A
mutation (also reported in the literature as V243A). This mutation is estimated to account for 20% of
pathogenic alleles in patients identified by newborn screening. When this test is ordered, results of
biochemical assays should be included with the specimen as they are necessary for accurate interpretation
of the VLCAD sequence analysis.
Useful For: Diagnostic confirmation of very long chain acyl-CoA dehydrogenase (VLCAD) deficiency
when familial mutations have been previously identified Carrier screening of at-risk individuals when a
mutation in the ACADVL gene has been identified in an affected family member
Interpretation: An interpretive report will be provided.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Andresen BS, Olpin S, Poorthuis BJ, et al: Clear correlation of genotype
with disease phenotype in very-long-chain acyl-CoA dehydrogenase deficiency. Am J Hum Genet
1999;64:479-494 2. Liebig M, Schymik I, Mueller M, et al: Neonatal screening for very long-chain
acyl-CoA dehydrogenase deficiency: enzymatic and molecular evaluation of neonates with elevated
C14:1-carnitine levels. Pediatrics 2006;118:1065-1069
Vibrio Culture, Stool
Clinical Information: Diarrhea may be caused by a number of agents (eg, bacteria, viruses, parasites,
and chemicals) and these agents may result in similar symptoms. A thorough patient history covering
symptoms, severity and duration of illness, age, travel history, food consumption, history of recent
antibiotic use, and illnesses in the family or other contacts will help the physician determine the
appropriate testing to be performed. Vibrio cholerae, the causative agent of endemic, epidemic, and
pandemic cholera, results in large volumes of rice-water stools due to the production of an enterotoxin.
Severe dehydration is of concern in patients without access to adequate medical care. In the United States,
Vibrio parahemolyticus is the most common cause of Vibrio disease. Vibrio parahemolyticus is associated
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