A small number of individuals have genetic mutations that cause them to have very low levels of magnesium (Mg2+), which can cause altered heart beats, seizures, and involuntary muscle contraction.
Study of these patients has provided a lot of our information about how Mg2+ levels are normally controlled, which is of clinical importance as it has been estimated that up to 60% of critically ill patients have low Mg2+ levels, and this is associated with increased mortality.
René Bindels and colleagues, at Radboud University Nijmegen Medical Centre, The Netherlands, have now identified a new gene mutation in a family with hypomagnesemia, providing new insight into the mechanisms that regulate Mg2+ levels.
In the study, a mutation in the KCNA1 gene, which makes a protein known as Kv1.1, was found to cause hypomagnesemia in a large family with many individuals suffering from the disease. Detailed analysis revealed that the mutation generated a nonfunctional Kv1.1 protein and that it affected Mg2+ reabsorption by the protein TRPM6 in a region of the kidney known as the distal convoluted tubule.
In an accompanying commentary, David Ellison, at Oregon Health & Science University, Portland, discusses the importance of the data and suggests how they might explain some of the clinical situations in which critically ill patients have low Mg2+ levels.
The research is published in the March 23, 2009, issue of the Journal of Clinical Investigation.
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