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NHLBI GO-ESP: Heart Cohorts Exome Sequencing Project (Siblings with Ischemic Stroke Study, SWISS)

The NHLBI "Grand Opportunity" Exome Sequencing Project (GO-ESP), a signature project of the NHLBI Recovery Act investment, was designed to identify genetic variants in coding regions (exons) of the human genome (the "exome") that are associated with heart, lung and blood diseases. These and related diseases that are of high impact to public health and individuals from diverse racial and ethnic groups will be studied. These data may help researchers understand the causes of disease, contributing to better ways to prevent, diagnose, and treat diseases, as well as determine whether to tailor prevention and treatments to specific populations. This could lead to more effective treatments and reduce the likelihood of side effects. GO-ESP is comprised of five collaborative components: 3 cohort consortia - HeartGO, LungGO, and WHISP - and 2 sequencing centers - BroadGO and SeattleGO.

The Siblings with Ischemic Stroke Study (SWISS) is an affected sibpair (ASP) study of patients and their brothers/sisters who have had similar strokes. The study was conducted to determine the genes that contribute to an individual's risk of developing an ischemic stroke (a stroke due to sudden interruption of blood flow to a part of the brain). Over 600 people have participated in SWISS, with the coordination of the recruitment and flow of the samples occurring at the Mayo Clinic, Jacksonville, FL, under the direction of James F. Meschia, MD. The University of Virginia (Stephen S. Rich, PhD) served as the analytic site for the genetic data. Participants were excluded from SWISS if they had stroke following an invasive cerebrovascular or cardiovascular procedure, if their stroke occurred shortly following an aneurismal subarachnoid hemorrhage, if the stroke occurred in the setting of a mechanical aortic or mitral valve, if the patient had definite CNS vasculitis or if the patient had a Mendelian mitochondrial stroke disorder, including CADASIL, MELAS, Fabry disease, sickle cell anemia or homocysteinemia.

For the NHLBI ESP, the youngest 51 ASPs (102 individuals) from SWISS were selected to undergo exome sequencing. These ASPs were selected from among all SWISS participants, excluding those pedigrees with individuals who had TOAST subtypes of stroke of other etiology or of stroke with undetermined etiology. In addition, the affected siblings were required to have the same TOAST subtype (both small vessel (lacunar) or both large vessel (atherosclerotic)). Of those selected, 98 samples passed initial quality control metrics, and 94 completed exome sequencing and were deposited in dbGaP.

An additional set of 590 samples from the SWISS collection has been genotyped on the ExomeChip that contained a subset of rare/infrequent variants identified by exome sequencing. These samples include 495 affected individuals (from multiple affected family members) as well as 95 unaffected family members. These genetic and phenotypic data also will reside in dbGaP.