The CFTR variant profile of Hispanic patients with cystic fibrosis: Impact on access to effective screening, diagnosis, and personalized medicine

Abstract

Hispanic patients comprise an appreciable and increasing proportion of patients with cystic fibrosis (CF) in the United States (US). Hispanic patients with CF are known to have increased morbidity and mortality compared to non‐Hispanic white patients with CF, and ongoing investigations are underway to identify contributing factors amenable to intervention in order to address the disparate health outcomes. One contributing factor is the different CF transmembrane conductance regulator (CFTR) variant profile observed in Hispanic patients with CF. The most common CFTR variant, p.Phe508del (legacy name F508del), is proportionally underrepresented in Hispanic patients with CF. This difference has implications for prenatal screening, newborn screening (NBS), and CFTR variant‐specific therapeutic options. In particular, the recent approval of a highly effective CFTR modulator for patients carrying at least one copy of F508del, elexacaftor/tezacaftor/ivacaftor triple combination therapy, underscores the potential for unequal access to personalized treatment for Hispanic patients with CF. We report the CFTR variant profiles of Hispanic patients with CF and non‐CF Hispanic infants with a false‐positive New York State CF NBS at a single center in New York City over a 5‐year study period, as an opportunity to address the racial and ethnic disparities that currently exist in CF screening, diagnosis, and treatment. In addition to the previously documented disparate prevalence of the CFTR variant F508del in Hispanic patients, we observed two CFTR variants, p.His609Arg (legacy name H609R) and p.Thr1036Asn (legacy name T1036N), frequently identified in our Hispanic patients of Ecuadorian and Mexican ancestry, respectively, that are not well‐described in the US population. The presence of population‐specific and individually rare CFTR variants in Hispanic patients with CF further accentuates the disparity in health outcomes, as these CFTR variants are often absent from prenatal and NBS CFTR variant panels, potentially delaying diagnosis, and without an approved CFTR variant‐specific therapy.

Cystic fibrosis-related mortality in the United States from 1999 to 2020: an observational analysis of time trends and disparities

“…Hispanic patients tend to acquire Pseudomonas infection more frequently and at an earlier age, have lower FEV1, and are underrepresented in clinical trials 34 , 37 – 40 . The differences in mortality may also be influenced by variations in the identification of genetic mutations, with 39% of CFTR variants in Hispanic CF individuals remaining unclassified 33 , 41 , 42 . Moreover, the heterogeneity in CFTR genotype distribution results in 25% of Hispanic CF patients currently being ineligible for available CFTR modulator therapy based on their genotypes, compared to 10% in non-Hispanic whites 26 .…”