Rather, specimens from infants known to have CF but without two clinically relevant CFTR variants were screened for del/dup using the Illumina CSA (detects deletions of exons 2–3 and exons 25–26 [22,23]), targeted real-time qPCR assays to assess exon copy number, CFTR-specific multiplex ligation-dependent probe amplification (MLPA)), gap-PCR assays, or Sanger sequencing. Here, CFTR is linked to cystic fibrosis.