Author(s): Merezhinskaya N, Fishbein WN, Davis JI, Foellmer JW
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Abstract We identified 5 patients with subnormal erythrocyte lactate transport plus symptoms and signs of muscle injury on exercise and heat exposure. All had transport rates below the 95\% envelope for normals. Three cases had rates 40-50\% of mean normal. One was found to have a missense mutation in monocarboxylate transporter 1 (MCT1), the gene for the red cell lactate transporter (also expressed in skeletal muscle), at a conserved site, which was not mutated in a cohort of 90 normal humans. The other 2 cases had a different missense mutation (at a nonconserved site), which was also not mutated in the normal cohort. All 3 patients were heterozygotes. We presume that these mutations are responsible for their subnormal lactate transport, and hence their muscle injury under environmental stress; homozygous patients should be more seriously compromised. The other 2 cases had lactate transport rates 60-65\% of mean normal, and their MCT1 revealed a third mutation, which proved to be a common polymorphism in the normal cohort. These 2 patients may be physiologic outliers in lactate transport, with their muscle damage arising from some other genetic defect. Copyright 2000 John Wiley & Sons, Inc.
This article was published in Muscle Nerve
and referenced in Journal of Nutrition Research