Scientists find gene defect link to heart disease

LONDON - Five generations of a family in Dallas,Texas have helped scientists discover a genetic mutation thatcauses a common birth defect and contributes to heart diseasein adults.

Researchers at the University of Texas Southwestern MedicalCenter in Dallas studied DNA from 11 members of the family,including children and adults, who suffered from aortic heartdisease.

They found that all of them had a mutation on a gene calledNOTCH1.

"Mutations in NOTCH1 cause an early developmental defect inthe aortic valve," said Dr Vidu Garg, an assistant professor ofpediatrics and molecular biology.

Researchers found a second mutation on the same gene inmembers of a smaller family in San Diego which they saidconfirmed their finding.

The aortic valve is normally composed of three flaps oftissue that open and close to enable blood to flow in onedirection.

But about one or two percent of the population are bornwith valves with only two flaps which make them susceptible toaortic valve stenosis. The condition, which narrows the passagethrough which blood exits the heart, can require surgery atbirth.

In severe cases the heart does not develop properly in thefetus and the child is born with an illness called hypoplasticleft heart syndrome -- a leading cause of heart disease deaths