Updated Newborn Screening Cystic Fibrosis 139 Mutation Panel
The State of Michigan Newborn Screening (NBS) Program is working to establish infrastructure and framework to expand second-tier molecular analysis for cystic fibrosis (CF) screening. These efforts are supported by funding from the Cystic Fibrosis Foundation and the Health Resources Services and Administration (HRSA).
Screening for cystic fibrosis in Michigan utilizes a two-tiered approach. In the 1st tier, immunoreactive trypsinogen (IRT) is measured in every infant’s NBS specimen. Elevated IRT levels are associated with CF. For infants identified with elevated IRT, a 2nd tier mutation analysis of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene is performed. This two-tiered approach is the consensus standard for NBS and has been in place since Michigan began CF NBS in 2007. Currently, 2nd tier testing in Michigan is performed using the FDA-cleared Luminex xTAG CFTR 60 v2 kit, which tests for the presence of 60 CF-causing CFTR variants. Beginning early 2025, the Michigan NBS laboratory will switch to the next generation sequencing (NGS) based Illumina TruSight Cystic Fibrosis 139-Variant Assay, more than doubling the number of detectable CFTR variants.
The use of the 139-variant assay will greatly improve equity of cystic fibrosis screening, as most additional CF-causing variants are more prevalent in non-white populations. However, the 139-variant panel does not cover every possible CF-causing variant and the Michigan NBS laboratory’s transition to a 139-variant panel is the start of a long-term process to expand the variant panel to continuously improve CF screening quality and equity.
Updated educational materials, including the list of CFTR variants included on the 139-variant panel, can be found on the NBS website at: Hereditary Disorders (michigan.gov)
For direct email updates, sign up for the NBS list serv at the following link: https://forms.office.com/g/rFHkMvSc2a
For questions or comments on this change, please contact the Newborn Screening Program via email at newbornscreening@michigan.gov or via phone at 517-335-4181.
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