Caution advised in the use of CFTR modulator treatment for individuals harboring specific CFTR variants.

In December 2020, the U.S. Food and Drug Administration (FDA) expanded the list of CFTR variants approved for treatment with CFTR modulators drugs from 39 to 183. Clinicians should be aware that individuals harboring certain variants approved for treatment may not respond to or benefit from this therapy. After review, the expert panel leading the CFTR2 project identified four categories of variants that may not result in a clinical response to modulator treatment: 15 variants assigned as non CF-causing; 45 variants of unknown significance; six variants known or suspected to cause mis-splicing as their primary defect rather than an amino acid substitution; and eight variants known to occur together in cis with another deleterious variant not expected to lead to CFTR protein (nonsense or frameshift). The potential risks and benefits of CFTR modulator therapy should be considered carefully for individuals harboring these variants.

Correlating Cystic Fibrosis Transmembrane Conductance Regulator Function with Clinical Features to Inform Precision Treatment of Cystic Fibrosis.

Rationale: The advent of precision treatment for cystic fibrosis using small-molecule therapeutics has created a need to estimate potential clinical improvements attributable to increases in cystic fibrosis transmembrane conductance regulator (CFTR) function. Objectives: To derive CFTR function of a variety of CFTR genotypes and correlate with key clinical features (sweat chloride concentration, pancreatic exocrine status, and lung function) to develop benchmarks for assessing response to CFTR modulators. Methods: CFTR function assigned to 226 unique CFTR genotypes was correlated with the clinical data of 54,671 individuals enrolled in the Clinical and Functional Translation of CFTR (CFTR2) project. Cross-sectional FEV1% predicted measurements were plotted by age at which measurement was obtained. Shifts in sweat chloride concentration and lung function reported in CFTR modulator trials were compared with function-phenotype correlations to assess potential efficacy of therapies. Measurements and Main Results: CFTR genotype function exhibited a logarithmic relationship with each clinical feature. Modest increases in CFTR function related to differing genotypes were associated with clinically relevant improvements in cross-sectional FEV1% predicted over a range of ages (6-82 yr). Therapeutic responses to modulators corresponded closely to predictions from the CFTR2-derived relationship between CFTR genotype function and phenotype. Conclusions: Increasing CFTR function in individuals with severe disease will have a proportionally greater effect on outcomes than similar increases in CFTR function in individuals with mild disease and should reverse a substantial fraction of the disease process. This study provides reference standards for clinical outcomes that may be achieved by increasing CFTR function.

Genomics and infectious disease: a call to identify the ethical, legal and social implications for public health and clinical practice.

Advances in genomics are contributing to the development of more effective, personalized approaches to the prevention and treatment of infectious diseases. Genetic sequencing technologies are furthering our understanding of how human and pathogen genomic factors - and their interactions - contribute to individual differences in immunologic responses to vaccines, infections and drug therapies. Such understanding will influence future policies and procedures for infectious disease management. With the potential for tailored interventions for particular individuals, populations or subpopulations, ethical, legal and social implications (ELSIs) may arise for public health and clinical practice. Potential considerations include balancing health-related benefits and harms between individuals and the larger community, minimizing threats to individual privacy and autonomy, and ensuring just distribution of scarce resources. In this Opinion, we consider the potential application of pathogen and host genomic information to particular viral infections that have large-scale public health consequences but differ in ELSI-relevant characteristics such as ease of transmission, chronicity, severity, preventability and treatability. We argue for the importance of anticipating these ELSI issues in advance of new scientific discoveries, and call for the development of strategies for identifying and exploring ethical questions that should be considered as clinical, public health and policy decisions are made.

Defining the disease liability of variants in the cystic fibrosis transmembrane conductance regulator gene.

Allelic heterogeneity in disease-causing genes presents a substantial challenge to the translation of genomic variation into clinical practice. Few of the almost 2,000 variants in the cystic fibrosis transmembrane conductance regulator gene CFTR have empirical evidence that they cause cystic fibrosis. To address this gap, we collected both genotype and phenotype data for 39,696 individuals with cystic fibrosis in registries and clinics in North America and Europe. In these individuals, 159 CFTR variants had an allele frequency of l0.01%. These variants were evaluated for both clinical severity and functional consequence, with 127 (80%) meeting both clinical and functional criteria consistent with disease. Assessment of disease penetrance in 2,188 fathers of individuals with cystic fibrosis enabled assignment of 12 of the remaining 32 variants as neutral, whereas the other 20 variants remained of indeterminate effect. This study illustrates that sourcing data directly from well-phenotyped subjects can address the gap in our ability to interpret clinically relevant genomic variation.

Assessing public attitudes on the retention and use of residual newborn screening blood samples: a focus group study.

This paper discusses attitudes and opinions of a diverse group of participants toward the retention and use of residual newborn blood samples for research. Data were drawn from focus groups based in six states in the USA, and results provide support for the retention and use of residual newborn blood samples for research when parental permission is asked beforehand. However, there were a number of concerns that also warrant attention for the development of policy and maintaining trust with the public, such as timing of permission, use of samples already stored, level of personal control of sample use and education. The results demonstrate the complexity of the topic and the ethical ambiguities associated with the retention and use of residual newborn blood samples.

State laws regarding the retention and use of residual newborn screening blood samples.

BACKGROUND: After newborn screening has been completed, many states retain residual newborn screening dried blood samples for various purposes, including program evaluation, quality assurance, and biomedical research. The extent to which states possess legal authority to retain residual dried blood samples (DBS) and use them for purposes unrelated to newborn screening is unclear. OBJECTIVE: The purpose of this study was to evaluate state laws regarding the retention and use of DBS. METHODS: State statutes and regulations related to newborn screening of all 50 states plus the District of Columbia were accessed online between November 2008 and December 2009 and reviewed by 2 independent reviewers to determine the extent to which the retention and use of DBS were addressed. RESULTS: The retention or use of DBS has not been addressed in 18 states. In 4 states, DBS becomes state property. Eight states require that parents be provided information regarding the retention of DBS. Parents in 5 states may request the destruction of their child's residual sample. Parental consent is required under certain circumstances to release DBS for research in 6 states. One state prohibits DBS from being used for research purposes. CONCLUSIONS: States have wide variability in their policies regarding the retention and use of DBS. Many states have not addressed key issues, and some states that retain DBS may be acting outside the scope of their legal authority. The lack of transparency on the part of states in retaining DBS may undermine public trust in state newborn screening programs and the research enterprise.