UPF1 and long COVID-19: We focused on the two loci that contained all mutations reported by Liu et al. (UPF1 exons 10-11 and exons 21–23). Because the relevant introns are very short, they were well covered by both the whole-exome and whole-genome sequencing used by Fang et al. Using relaxed mutation-calling criteria to maximize sensitivity (details in Materials and methods), we identified somatic UPF1 mutations in samples from 6 of 17 PASC patients.