Ain't got rhythm

In the February 6 Nature, Peter Mohler and colleagues report the discovery of mutations in the gene encoding ankyrin-B (known as ankyrin 2) in patients suffering from cardiac arrhythmia and inherited long-QT syndrome (Nature, 421:634-639, February 6, 2003).

An A-to-G transition results in a glutamic acid-to-glycine substitution. Mice heterozygote for a null mutation in ANKB also displayed cardiomyocyte defects, cardiac arrhythmia and sudden death after exercise. The ankyrin-B protein appears to be important for regulating expression of the sodium pump, the sodium/calcium exchanger, inositol-1,4,5-triphospate receptors, as well as Ca²⁺ signaling. This is the first report of a mutation in congenital long-QT syndrome that affects a protein other than an ion channel or channel subunit.