Characterizing Populations Based on Proximity to a Fragile X Syndrome Specialty Clinic.

Fragile X syndrome (FXS) is a rare condition that can require lifelong specialized care for optimal management. We describe census-based characteristics of general U.S. populations defined by proximity to FXS specialty clinics to better understand potential barriers to access. We used Geographic Information System software to estimate drive times from U.S. census tract centroids to FXS clinics. Of the contiguous U.S. population, 36.4% lives ≤1 hour from the closest FXS clinic in the same state; 32.4% live >1 to 4 hours, 7.3% live >4 hours, and 23.8% have no FXS clinic in their state. Individuals residing >1 hr from or in a state without an FXS clinic, compared to <1 hr, were more commonly non-Hispanic White, had household income below 150% poverty level, had one or more disabilities, and lived in a household without an internet subscription. Populations living ≤1 hr from an FXS clinic more commonly spoke limited English, lived in multiunit housing, and did not have a vehicle. These results can be used to identify areas of higher need for improving access to specialty care, inform efforts to reduce disparities related to access, and facilitate more optimal healthcare for people with FXS.