Child Has Only Six Adult Teeth In Jaw. Heart Beats Painful, Out Of Rhythm. Suggestions?

Hi. My son is 10. We have recently learned that he only has six adult teeth in his jaw. The dentist said this may be part of a syndrome that could affect other organs? My son has for two years now complained that every now and again his heart beats painfully hard and out of rythm. It hurts his chest and he sucks his breath in from the pain. When the rythm returns to normal, he is okay. This normally happens when he s just sitting at home or driving with me in the car, not during sport or exertion. His father died six months ago at age 51 of sudden cardiac arrest . His uncle had a heart attack two years ago and both his grandfathers, maternal and paternal, died before age 60 due to heart problems. I m not sure if they had sudden cardiac arrest or heart attacks.