NEW YORK – A colossal international effort has yielded the first comprehensive look at how our DNA works, an encyclopedia of information that will rewrite the textbooks and offer new insights into the biology of disease.

For one thing, it may help explain why some people are more prone to common ailments such as high blood pressure and heart disease.

The findings, reported Wednesday by more than 500 scientists, reveal extraordinarily complex networks that tell our genes what to do and when, with millions of on-off switches.