Table 2 Summary of Study Procedures

Study neurologist identifies patient who meets criteria for SWISS.

Proband gives written informed consent and receives study invitation letters to give to siblings.

Interested siblings send contact information to Clinical Coordinating Center.

Phase IIA – Verifying discordance

Clinical Coordinating Center staff conducts structured telephone interview with presumed discordant sibling to verify absence of stroke (discordance) and sends informed consent form to verifed discordant siblings.

Verified discordant sibling sends signed consent form to Clinical Coordinating Center.

Phase IIB – Verifying concordance

Clinical Coordinating Center sends request forms for medical records and informed consent forms to presumed concordant siblings.

Clinical Coordinating Center uses returned, signed forms to request medical records.

Stroke Verification Committee reviews medical records to verify stroke diagnosis (concordance).

Phase III – Acquiring blood for genetic analysis

Home health agency phlebotomist visits homes of proband, verified concordant sibling, and (if applicable) verified discordant sibling to obtain blood samples.

Home health agency forwards blood samples to DNA Bank.

Phase IV – Genome-wide screen

DNA Bank stores blood samples and notifies Genetics Laboratory when samples from 300 concordant sibling pairs have been collected.

Genetics Laboratory performs genome-wide screen.