Utility of a buccal swab point-of-care test for the IFNL4 genotype in the era of direct acting antivirals for hepatitis C virus

BackgroundThe CC genotype of the IFNL4 gene is known to be associated with increased Hepatitis C (HCV) cure rates with interferon-based therapy and may contribute to cure with direct acting antivirals. The Genedrive (R) IFNL4 is a CE marked Point of Care (PoC) molecular diagnostic test, designed for in vitro diagnostic use to provide rapid, real-time detection of IFNL4 genotype status for SNP rs12979860. Methods120 Participants were consented to a substudy comparing IFNL4 genotyping results from a buccal swab analysed on the Genedrive (R) platform with results generated using the Affymetix UK Biobank array considered to be the gold standard. ResultsBuccal swabs were taken from 120 participants for PoC IFNL4 testing and a whole blood sample for genetic sequencing. Whole blood genotyping vs. buccal swab PoC testing identified 40 (33%), 65 (54%), and 15 (13%) had CC, CT and TT IFNL4 genotype respectively. The Buccal swab PoC identified 38 (32%) CC, 64 (53%) CT and 18 (15%) TT IFNL4 genotype respectively. The sensitivity and specificity of the buccal swab test to detect CC vs non-CC was 90% (95% CI 76-97%) and 98% (95% CI 91-100%) respectively. ConclusionsThe buccal swab test was better at correctly identifying non-CC genotypes than CC genotypes. The high specificity of the Genedrive (R) assay prevents CT/TT genotypes being mistaken for CC, and could avoid patients being identified as potentially 'good responders' to interferon-based therapy.