Gene mutation in kids causes odd heart rate

WASHINGTON - Italian researchers say they have discovered a genetic mutation that causes an abnormally fast heart rate that can suddenly kill children at play or under stress.

Several mutations in a single gene can cause the rare and hard-to-diagnose syndrome, known as catacholamineric polymorphic ventricular tachycardia (CPVT).

It strikes children during physical exertion or when they feel strong emotions, the team at the University of Pavia say.

"Finding the gene may help to identify individuals at risk," says Dr Silvia Priori, who led the study.

Her team looked at the genes of 12 people with CPVT.

Knowing that calcium levels are important to how well cells work, they targeted a gene called human cardiac ryanodine receptor gene (hRyR2), which controls the levels of calcium inside heart cells.

"Patients with CPVT, as a consequence of the mutation in the ryanodine gene, have an increased sensitivity to calcium.

"Therefore, intense stimulation due to emotional stress or increased physical activity may lead to calcium overload and precipitate severe arrhythmias," Dr Priori says.

The team found four mutations, each a one-letter change in the genetic code. In three cases, the mutations were not inherited from the parents, who had normal genes.

"None of the mutations was present in DNA obtained from 400 normal subjects," they wrote in the American Heart Association journal Circulation.

Knowing about the gene could help doctors better diagnose the condition.

- REUTERS