Challenges to Assessing the Prevalence of Cystic Fibrosis in the Caribbean

: Cystic fibrosis (CF) is likely underdiagnosed in Caribbean populations due to non-representative cystic fibrosis transmembrane conductance regulator (CFTR) variant screening panels, limited newborn screening programs, and structural healthcare barriers. Data from 2022 indicate substantial populations with European ancestry in Puerto Rico (1.4 M, 42.7%) and the Dominican Republic (1.4 M, 57.9%), yet the true burden of CF in the broader Caribbean remains largely undocumented. WORKING HYPOTHESIS: Current diagnostic frameworks, largely based on European-derived CFTR variant distributions, fail to capture the true burden of CF in Caribbean populations, leading to underestimated prevalence and delayed or missed diagnoses. OBJECTIVES: To synthesize registry, clinical, and published data to identify barriers to accurately assessing CF prevalence in Caribbean populations. STUDY DESIGN AND METHODS: This narrative literature review integrates CF registries, published data on CFTR variant distribution, population ancestry data, and clinical observations from CF centers in Puerto Rico and the Dominican Republic. Clinical insights were derived from pediatric patients evaluated at the Pediatric Rare Lung and Asthma Institute in Puerto Rico and the CF Clinic at Robert Reid Cabral Children's Hospital in the Dominican Republic. RESULTS: CFTR variant patterns differ from those in the United States, with higher frequencies of rare variants such as p.Ala559Thr. Standard screening panels may miss these variants, contributing to underdiagnosis. Limited newborn screening, misdiagnosis, and restricted access to CFTR modulator therapies further exacerbate disparities. CONCLUSIONS: Structural, diagnostic, and genetic factors hinder accurate CF prevalence estimates in the Caribbean, highlighting the need for region-specific research, improved screening, and expanded access to therapies.