Mutations in genes which code for sodium ion channel proteins have emerged as the most important genetic factors associated with epilepsy, cardiac rhythm disorders, skeletal muscle channelopathies and pain disorders. Geneticists in partnership with neurologists and cardiologists are often asked to comment on the clinical significance of specific mutations. Comparing over 1300 sodium ion channel mutations in diseases affecting the central and peripheral nervous system, heart and muscle, we have identified many similarities in genetic and clinical characteristics across this ion channel family. These findings should lead to a better understanding of the clinical significance of specific mutations, aiding geneticists and physicians in the interpretation of genetic variants and in counselling individuals and their families. (By Dr Andreas Brunklaus, http://jmg.bmj.com/content/early/2014/08/27/jmedgenet-2014-102608 )