The present invention provides methods and materials to identify genetic
abnormalities that predispose an individual to ion-channel diseases. The
invention provides four polymorphic sites in the KCNQ1 gene that cause
reduced conductance of the associated potassium ion channel current and a
variant form of the KCNE1 gene which causes decreased conductance though
the channel. The variant form of KCNE1 also acts synergistically with
variants of KCNQ1 to cause further decreased conductance than either
variant alone. The invention further provides polymorphisms in ion
channel genes showing a higher frequency in populations afflicted with
ion channel diseases or within control groups. The detection of these
polymorphic sites that produce the potassium ion channel protein variants
in either heterozygous or homozygous form in a subject indicates that the
subject has, or is susceptible to, ion channel diseases such as
congenital or acquired cardiac arrhythmia, LQT syndrome, SIDS, epilepsy,
or hearing loss.
