An ion channel disease.
Ion channel diseases are ion-channel specific, e.g. if you have a disease in a certain voltage-gated calcium channel, it doesn’t automatically mean you will also have a disease in, say, a sodium channel.
Some ion channel diseases are congenital (i.e. “caused by the genes”) and others are acquired.
There are many factors which can make the situation better or worse for someone who has an ion channel disease.