REFINEMENT OF NEWBORN SCREENING FOR CYSTIC FIBROSIS WITH NEXT GENERATION
SEQUENCING
Abstract
Background: Newborn screening (NBS) for cystic fibrosis (CF)
has been underway universally in the USA for more than a decade, as well
in most European countries, and algorithms have been evolving throughout
this period with quality improvement projects as immunoreactive
trypsinogen determinations alone have been transformed to a 2-tier
strategy with DNA analyses. Objective: To apply next generation
sequencing (NGS) as a method for expanding the DNA tier for identifying
variants in the cystic fibrosis transmembrane conductance regulator (
CFTR) gene with minimization of unintended outcomes.
Design: Sequential quality improvement project in three phases
using plan coupled to statewide follow up and analysis of screening
outcomes in comparison to other NBS programs that use CFTR
sequencing. Results: After demonstrating feasibility in the
first phase, we studied an IRT/NGS algorithm that included CFTR
Variants with Varying Clinical Consequences (VVCCs). This revealed a
high identification of CF patients with 2-variants detected through
screening, but for every CF case there were 1.4 with cystic fibrosis
metabolic syndrome/cystic fibrosis screen positive, inconclusive
diagnosis (CRMS/CFSPID). This led us to a third phase of quality
improvement in which the VVCCs were eliminated except for R117H,
resulting in 94% 2-variant detection of patients and 0.44:1 ratio of
CRMS/CFSPID to CF. Conclusion: NGS can be used with IRT as an
effective method of identifying infants at risk for CF without an
appreciable increase in detection of either carriers or CRMS/CFSPID
cases.