CFTR and cystic fibrosis: Interestingly, in the Chinese CFTR variant spectrum, though not yet well-established, only four CF alleles with gross rearrangement events were observed, including one allele with △E7-E11 (c.744-?_1584 +?del), [32] one with △E18-E20 (c.2909-?_3367 +?del), [32] and two with △E20 (c.3140-454_c.3367 + 249del931ins13).