Elinor Langfelder-Schwind

Cystic fibrosis is an autosomal recessive condition historically reported to be predominantly in those of European ancestry; however, more cases of CF are reported in those with non‐European ancestry as we improve diagnostic awareness and aptitude. We report two cases of Somali siblings with rare CFTR 896delT (c.764del; p.Ile255ThrfsX6; dbSNP rs2485020167; ClinVar ID 2682475; NM_000492.4:c.764del) homozygous variants who manifested classic CF lung and hepatic disease. They presented with elevated immunoreactive trypsinogen on newborn screen but required exon sequencing to confirm their rare variant. This type of variant causes a frameshift that leads to an early stop codon; therefore, there is currently no available disease‐modulating therapy. Our cases highlight the clinical phenotype of this variant and increase awareness of the importance of inclusivity in our current CF screening methods.

Variants in the cystic fibrosis transmembrane conductance regulator ( CFTR ) gene, which causes cystic fibrosis, have become increasingly well‐characterized in recent decades. However, clinicians remain challenged by CFTR variants that result in variable expressivity and reduced penetrance, including the variant R117H (c.350G>A) and the intron 9 poly‐thymidine (poly‐T) and poly‐thymidine‐guanosine (TG) tracts, highlighting a knowledge gap that impacts the delivery of accurate information to patients and families. To address this gap, we developed an educational resource that provides descriptive likelihoods of specific phenotypes that may result from genotypes including R117H and the poly‐T and TG tracts. Development of the resource was grounded in an extensive literature review, clinical expertise, and publicly available CFTR variant databases, with feedback incorporated from CF clinicians, genetic counselors, and CF content experts. Genotypes were determined to have very low, low, moderate, high, or very high likelihood of resulting in CF, CFTR‐related disorder (CFTR‐RD), no symptoms, or the designation of CFTR‐related metabolic syndrome/CF‐screen positive, inconclusive diagnosis (CRMS/CFSPID) following CF newborn screening. The resource described in this report is intended to help clinicians navigate the uncertainty surrounding potential diagnostic scenarios to present accurate assessments to patients and families, a critical component of CF genetic testing and counseling.

As of December 2009, cystic fibrosis (CF) newborn screening (NBS) is performed in all 50 US states and the District of Columbia. Widespread implementation of CF newborn screening (CFNBS) in the US and internationally has brought about new and varied challenges. Immunoreactive trypsinogen (IRT) remains the first, albeit imperfect, biomarker used universally in the screening process. Advances in genetic testing have provided an opportunity for newborn screening programs to add CFTR sequencing tiers to their algorithms. This in turn will enable earlier identification of babies with CF and improve longer-term outcomes through prompt treatment and intervention. CFTR sequencing has led to the ability to identify infants with CF from diverse ethnic and racial backgrounds more equitably while also identifying an increasing proportion of infants with inconclusive diagnoses. Using the evolution of the New York State CF newborn screening program as a guide, this review outlines the basic steps in a universal CF newborn screening program, considers how to reduce bias, highlights challenges, offers guidance to address these challenges and provides recommendations for future consideration.

With the advent of highly effective modulator therapies, many people with cystic fibrosis (CF) are living longer, healthier lives. Pregnancy rates for women with CF more than doubled between 2019 and 2021, reflecting increases in both planned and unplanned pregnancies. For men with CF, CF-associated infertility can be mitigated with assistive reproductive technology, yet patient knowledge of these challenges and options is variable. Preconception and prenatal counseling for individuals with CF and for parents of children with CF who wish to expand their families requires nuanced discussions to promote informed reproductive decisions, drawing from a combination of standard practice recommendations and CF-specific assessments. This review article synthesizes the current literature and practice recommendations regarding reproductive counseling and care in CF, outlining the role of genetic counseling, carrier screening, teratogen counseling, in vitro fertilization and pre-implantation genetic diagnosis, and careful assessment and management of cystic fibrosis-related diabetes when present. Via a multidisciplinary, patient-centered approach, clinicians can support adults with CF and parents of children with CF as they make informed reproductive decisions and embark on family planning.