Abstract Body: Background : Fibromuscular dysplasia (FMD) is a systemic, non-atherosclerotic arterial disease that predominantly affects women and can affect multiple arterial beds. FMD is a complex, polygenic disorder, and as such, family members of individuals with FMD represent a group of individuals at higher risk of FMD and FMD-related manifestations of arterial dysplasia than baseline population risk. However, little is known regarding the specific nature of that risk, including the potential subclinical manifestations that are detectable on imaging without overt signs or symptoms. To evaluate such potential clinical manifestations, we sought to perform a pilot study where head-to-pelvis angiographic CT imaging was done for family members of individuals with FMD.

Methods: We evaluated 21 families with a proband with angiographically confirmed FMD. Family members of FMD probands were reviewed for eligibility and interest in head-to-pelvis CT-angiographic imaging, of which 10 individuals among 7 families ultimately participated in this pilot study.

Results: The pilot study of family members of 7 FMD probands comprised 10 family members (100% women) who underwent CT-angiographic imaging from head through pelvis using a standardized imaging protocol with dedicated head/neck, chest, and abdomen/pelvis radiologist readers. The average age was 45.6 years (range 20 – 68 years). We identified findings of arterial dysplasia consistent with FMD (average age 57.4 years old at the time of imaging) in 5 individuals scanned, with 3 individuals found to have affected arterial beds in both their head/neck region as well as in their abdomen/pelvis (renal and external iliac arteries). Family member s known to be affected before the study imaging were all found to have more extensive arterial involvement than they were previously aware of based on prior clinical evaluations.

Conclusion: Our results confirm an elevated risk of FMD and other findings consistent with underlying arterial dysplasia in family members of individuals with FMD. The findings were both subclinical and clinically apparent in some cases. Ultimately, determining best practices for screening family members of individuals with FMD will require additional research with a larger cohort.