By DELTHIA RICKS / delthia.ricks@newsday.com

Long Island scientists have embarked on a study of sets of sisters in which one has lupus and one or more do not with the hope of bringing new clarity to a disease that tends to stalk families.

Drs. Peter Gregersen and Betty Diamond of the Feinstein Institute in Manhasset have begun their recruitment of siblings into the project with one goal in mind: finding the genetic and environmental interactions that lead to lupus.

"What we want to do is look at sisters of women with lupus because sisters are the ones most at risk," said Diamond, director of the Center for Autoimmune and Musculoskeletal Diseases at the Feinstein, a division of the North Shore-LIJ Health System.

Autoimmune diseases occur when the body's own proteins act as turncoats, attacking the heart, brain, kidneys and other tissues. People with lupus can suffer strokes, heart attacks and kidney failure.

Diamond said it's common for one sister to have lupus while another may develop rheumatoid arthritis, another autoimmune condition.

Sisters are being recruited from throughout Long Island as well as around the country to unmask many of the mysteries of the insidious condition. Lupus is nine times more likely to strike women.

The idea of studying sisters is new to lupus research but not to science. Since 2004, the Sister Study of breast cancer has focused on environmental factors that may be associated with that disease.

But Gregersen, director of the Feinstein's Center for Genomics and Human Genetics, said because lupus lacks breast cancer's public profile, recruiting siblings will probably be more challenging. "Breast cancer has an enormous presence in the lay press, so recruiting enough women for that study was somewhat easier," he said.

A lupus pilot study plans to enroll 400 siblings for the research effort that will last two years. Doctors ultimately hope to enroll 4,000 nationwide.

Sandra C. Raymond, president and chief executive of the Lupus Foundation of America in Washington, D.C., said the Long Island investigation is expected to break new ground. "This is a pivotal study to help us better understand what's going on in lupus," she said.