Actionability of unanticipated monogenic disease risks in newborn genomic screening: Findings from the BabySeq Project.

Newborn genomic sequencing (NBSeq) to screen for medically important genetic information is of considerable interest but data characterizing the actionability of such findings, and the downstream medical efforts in response to discovery of unanticipated genetic risk variants, are lacking. From a clinical trial of comprehensive exome sequencing in 127 apparently healthy infants and 32 infants in intensive care, we previously identified 17 infants (10.7%) with unanticipated monogenic disease risks (uMDRs). In this analysis, we assessed actionability for each of these uMDRs with a modified ClinGen actionability semiquantitative metric (CASQM) and created radar plots representing degrees of penetrance of the condition, severity of the condition, effectiveness of intervention, and tolerability of intervention. In addition, we followed each of these infants for 3-5 years after disclosure and tracked the medical actions prompted by these findings. All 17 uMDR findings were scored as moderately or highly actionable on the CASQM (mean 9, range: 7-11 on a 0-12 scale) and several distinctive visual patterns emerged on the radar plots. In three infants, uMDRs revealed unsuspected genetic etiologies for existing phenotypes, and in the remaining 14 infants, uMDRs provided risk stratification for future medical surveillance. In 13 infants, uMDRs prompted screening for at-risk family members, three of whom underwent cancer-risk-reducing surgeries. Although assessments of clinical utility and cost-effectiveness will require larger datasets, these findings suggest that large-scale comprehensive sequencing of newborns will reveal numerous actionable uMDRs and precipitate substantial, and in some cases lifesaving, downstream medical care in newborns and their family members.

Urine Proteomics for Noninvasive Monitoring of Biomarkers in Bronchopulmonary Dysplasia.

INTRODUCTION: Current techniques to diagnose and/or monitor critically ill neonates with bronchopulmonary dysplasia (BPD) require invasive sampling of body fluids, which is suboptimal in these frail neonates. We tested our hypothesis that it is feasible to use noninvasively collected urine samples for proteomics from extremely low gestational age newborns (ELGANs) at risk for BPD to confirm previously identified proteins and biomarkers associated with BPD. METHODS: We developed a robust high-throughput urine proteomics methodology that requires only 50 µL of urine. We utilized the methodology with a proof-of-concept study validating proteins previously identified in invasively collected sample types such as blood and/or tracheal aspirates on urine collected within 72 h of birth from ELGANs (gestational age [26 ± 1.2] weeks) who were admitted to a single Neonatal Intensive Care Unit (NICU), half of whom eventually developed BPD (n = 21), while the other half served as controls (n = 21). RESULTS: Our high-throughput urine proteomics approach clearly identified several BPD-associated changes in the urine proteome recapitulating expected blood proteome changes, and several urinary proteins predicted BPD risk. Interestingly, 16 of the identified urinary proteins are known targets of drugs approved by the Food and Drug Administration. CONCLUSION: In addition to validating numerous proteins, previously found in invasively collected blood, tracheal aspirate, and bronchoalveolar lavage, that have been implicated in BPD pathophysiology, urine proteomics also suggested novel potential therapeutic targets. Ease of access to urine could allow for sequential proteomic evaluations for longitudinal monitoring of disease progression and impact of therapeutic intervention in future studies.

A role for abdominal ultrasound in discriminating suspected necrotizing enterocolitis in congenital heart disease patients.

PURPOSE: We evaluated the diagnostic utility of abdominal ultrasound (AUS), an adjunct to abdominal X-ray (AXR), for necrotizing enterocolitis (NEC) in congenital heart disease (CHD) patients. METHODS: 86 patients with suspected NEC from 2009 to 2018 were classified as with CHD (n = 18) if they required cardiac intervention versus without CHD (n = 68). Clinical and radiological data were collected, including AXR and AUS concordance. Wilcoxon rank-sum test and Fisher's exact test were performed. RESULTS: CHD patients had higher birth weights (p < 0.001) and gestational ages (p < 0.001) than non-CHD patients. CHD patients presented more frequently with hypotension (p = 0.041) and less frequently with bilious emesis (p < 0.001). Overall, CHD patients were less likely to have AUS findings of pneumatosis (33.3 vs. 72.1%; p = 0.005) and decreased mural flow (0 vs. 20.6%; p = 0.035) compared to non-CHD patients. On concordance analysis, CHD patients had 3.9-fold more discordant studies with pneumatosis on AXR but not on AUS (33.3 vs. 8.8%; p = 0.016) compared to non-CHD patients. Urgent surgery was required in 5.6% of CHD patients versus 16.2% of non-CHD patients. CONCLUSION: CHD patients with suspected NEC represent a distinct clinical population. AUS has particular utility in assessing findings of bowel viability in the CHD NEC population, reflecting reduced rates of surgical NEC.

Genetic counseling access for parents of newborns who screen positive for cystic fibrosis: Consensus guidelines.

INTRODUCTION: A risk associated with cystic fibrosis newborn screening (CFNBS) is parental misunderstanding of genetic information generated by the over 6600 positive screens reported annually in the United States. CFNBS algorithms incorporating DNA analysis can generate genetic information that requires clinical interpretation and has significance for the newborn, parents, and other relatives. Engagement between CF care centers and trained genetic counseling providers, such as licensed and/or certified genetic counselors (GCs), is variable and limited in providing information to CFNBS positive (CFNBS+) families. METHODS: Using a modified Delphi process, a workgroup of CFNBS experts developed recommendation statements for engagement of genetic counseling services in CF care centers where CFNBS + diagnostic evaluations are performed. Statements were assessed over three rounds of surveys, one face-to-face meeting, and through public feedback. RESULTS: Seventeen statements achieved >80% consensus (range: 82%-100%). The workgroup affirmed prior CFF policy statements recommending genetic counseling for parents of infants with CFNBS+. The remaining statements addressed infrastructure and logistics of genetic counseling services, including defining appropriate training for genetic counseling providers and counseling content, establishing a path to equal access to genetic counseling providers across CF care centers, and setting a standard for client-centered CFNBS genetic counseling that is respectful of diverse patient needs and autonomy. CONCLUSIONS: Implementation of client-centered genetic counseling for CFNBS+ families in CF care centers by providers with expertise in both CF and genetic counseling will require efforts to further define core concepts, enhance the education of providers, and develop opportunities for access via telemedicine.

Differences in clinical and laboratory biomarkers for short and long-term respiratory outcomes in preterm neonates.

BACKGROUND: Pulmonary outcome of premature neonates has focused more on short-term than long-term respiratory morbidities. OBJECTIVE: Describe risk factors/biomarkers associated with short-term (bronchopulmonary dysplasia [BPD]) (supplemental oxygen use at 36 weeks postmenstrual age [PMA]) and longer-term (chronic respiratory morbidity [CRM]) (respiratory related symptoms, medications, medical/emergency visits, hospitalizations at 6-12 months corrected gestational age [CGA]) respiratory outcomes in a longitudinal cohort. DESIGN/METHODS: Neonates born at 24-29-week gestation were prospectively followed to 6-12-month CGA. Associations between clinical and laboratory risk factors/biomarkers of BPD and CRM were explored. RESULTS: Of 86 subjects, 94% survived. Outcomes were available for 89% at 36-week PMA (BPD present in 42% of infants) and 72% at 6-12-month CGA (CRM present in 47% of infants). For the 54 infants with known outcomes for both BPD and CRM, diagnoses were discordant in 41%. BPD was associated with lower birthweight and birthweight Z-score for GA, lower Apgar scores, more surfactant doses, higher SNAPPE-II scores, highest Day 1 inspired oxygen concentration, Day 7 oxygen use, prolonged ventilatory support, bacteremia, necrotizing enterocolitis, and treated patent ductus arteriosus. CRM was associated with lower Apgar scores, Day 7 oxygen use and higher urine vascular endothelial growth factor. Patterns of plasma and urine lipid oxidation products differed in the two outcomes. CONCLUSION: In this hypothesis generating and exploratory study, BPD and CRM were associated with different risk factors/biomarker patterns. Concordance between these two outcomes was weak. Strategies for reducing CRM should be studied in cohorts identified by appropriate early risk factors/biomarkers.

Abdominal ultrasound findings contribute to a multivariable predictive risk score for surgical necrotizing enterocolitis: A pilot study.

BACKGROUND: Abdominal ultrasound (AUS) is a promising adjunct to abdominal x-ray (AXR) for evaluating necrotizing enterocolitis (NEC). We developed a multivariable risk score incorporating AUS to predict surgical NEC. METHODS: 83 patients were evaluated by AXR and AUS for suspected NEC. A subset had surgical NEC. Multivariate logistic regression determined predictors of surgical NEC, which were incorporated into a risk score. RESULTS: 14/83 patients (16.9%) had surgical NEC. 10/83 (12.0%) patients required acute intervention, while 4/83 (4.8%) patients only required delayed surgery. Four predictors of surgical NEC were identified: abdominal wall erythema (OR: 8.2, p = 0.048), portal venous gas on AXR (OR: 29.8, p = 0.014), and echogenic free fluid (OR: 17.2, p = 0.027) and bowel wall thickening (OR: 12.5, p = 0.030) on AUS. A multivariable risk score incorporating these predictors had excellent area-under-the-curve of 0.937 (95% CI: 0.879-0.994). CONCLUSIONS: AUS, as an adjunct to physical exam and AXR, has utility for predicting surgical NEC.

Specificity of International Classification of Diseases codes for bronchopulmonary dysplasia: an investigation using electronic health record data and a large insurance database.

OBJECTIVE: International Classification of Diseases (ICD) codes in electronic health records (EHRs) are increasingly used for health services research, in spite of unknown diagnostic accuracy. The accuracy of ICD codes to identify bronchopulmonary dysplasia (BPD) is unknown. STUDY DESIGN: Retrospective cohort study in a single-center NICU (n = 166) to evaluate sensitivity and specificity of ICD-10 codes for the diagnosis of BPD. Analysis of large insurance claims database (n = 7887) to determine date of assignment of the code. RESULTS: The sensitivity of any BPD-related ICD codes ranged from 0.82 to 0.95, while the specificity ranged from 0.25 to 0.36. In a large national insurance database, the most common date of ICD-9 or ICD-10 code assignment was the day of birth, which is inconsistent with the clinical definition. CONCLUSIONS: ICD codes registered for BPD are unlikely to accurately reflect the current clinical definition and should be interpreted with caution.

Practice variation of genetic counselor engagement in the cystic fibrosis newborn screen-positive diagnostic resolution process.

Families of infants with a positive newborn screen for cystic fibrosis (CFNBS+) have well-characterized genetic counseling needs, including understanding the implications of diagnostic categorization. However, degree of involvement of genetic counselors (GCs) in the CFNBS+ diagnostic resolution process varies. This project explored GC engagement with US CF care centers in the diagnostic resolution process for CFNBS+ infants. Surveys were emailed to 713 Cystic Fibrosis Foundation-accredited CF center directors and clinic coordinators and 4,517 GCs. Respondents from institutions providing CFNBS+ diagnostic resolution were categorized by level of engagement between the CF center and GC: GC is part of or embedded in CF center (GC-engaged); GC is independent of CF center but receives CFNBS+ referrals (GC-referral); GC is uninvolved (non-engaged)] in CF center or CFNBS+ diagnostic resolution process. Responses from 125 CF center directors and clinic coordinators (17.5%) and 174 GCs (3.8%) were received. Analysis targeted responses from 84 center directors and clinic coordinators and 52 GCs, estimated to represent 24%-48% and 29% of 175 pediatric CF care centers, respectively. Nearly 40% of CF center directors or clinic coordinators never refer CFNBS+ infants to GCs. Respondents from GC-engaged CF centers reported that GCs provide unique and valuable services, understand CF at a high level, improve efficiency of the CFNBS+ diagnostic resolution process, and should be part of the CF care team; respondents from non-engaged CF centers reported negative views of GCs' value and knowledge (all p < .05). GCs engaged with CF centers were more likely to report that their services were valued by and accessible to CF centers (both p < .05). At all levels of engagement with CF centers, GCs were comfortable discussing CF genotype-phenotype correlation, variants of unknown significance, quality of life, and therapies. These results highlight a need to address practice variation in CFNBS+ genetic counseling and improve access to GCs' services.

Role of Genetic Susceptibility in the Development of Bronchopulmonary Dysplasia.

OBJECTIVE: To assess heritable contributions to bronchopulmonary dysplasia (BPD) risk in a twin cohort restricted to gestational age at birth <29 weeks. STUDY DESIGN: A total of 250 twin pairs (192 dichorionic, 58 monochorionic) born <29 weeks gestational age with known BPD status were identified. Three statistical methods applicable to twin cohorts (χ2 test, intraclass correlations [ICCs], and ACE modeling [additive genetic or A, common environmental or C, and unique environmental or E components]) were applied. Heritability was estimated as percent variability from A. Identical methods were applied to a subcohort defined by zygosity and to an independent validation cohort. RESULTS: χ2 analyses comparing whether neither, 1, or both of monochorionic (23, 19, 16) and dichorionic (88, 56, 48) twin pairs developed BPD revealed no difference. Although there was similarity in BPD outcome within both monochorionic and dichorionic twin pairs by ICC (monochorionic ICC = 0.34, 95% CI [0.08, 0.55]; dichorionic ICC = 0.39, 95% CI [0.25, 0.51]), monochorionic twins were not more likely than dichorionic twins to have the same outcome (P = .70). ACE modeling revealed no contribution of heritability to BPD risk (% A = 0.0%, 95% CI [0.0%, 43.1%]). Validation and zygosity based cohort results were similar. CONCLUSIONS: Our analysis suggests that heritability is not a major contributor to BPD risk in preterm infants <29 weeks gestational age.

Diagnosis of Cystic Fibrosis in Screened Populations.

OBJECTIVE: Cystic fibrosis (CF) can be difficult to diagnose, even when newborn screening (NBS) tests yield positive results. This challenge is exacerbated by the multitude of NBS protocols, misunderstandings about screening vs diagnostic tests, and the lack of guidelines for presumptive diagnoses. There is also confusion regarding the designation of age at diagnosis. STUDY DESIGN: To improve diagnosis and achieve standardization in definitions worldwide, the CF Foundation convened a committee of 32 experts with a mission to develop clear and actionable consensus guidelines on diagnosis of CF with an emphasis on screened populations, especially the newborn population. A comprehensive literature review was performed with emphasis on relevant articles published during the past decade. RESULTS: After reviewing the common screening protocols and outcome scenarios, 14 of 27 consensus statements were drafted that apply to screened populations. These were approved by 80% or more of the participants. CONCLUSIONS: It is recommended that all diagnoses be established by demonstrating dysfunction of the CF transmembrane conductance regulator (CFTR) channel, initially with a sweat chloride test and, when needed, potentially with newer methods assessing membrane transport directly, such as intestinal current measurements. Even in babies with 2 CF-causing mutations detected via NBS, diagnosis must be confirmed by demonstrating CFTR dysfunction. The committee also recommends that the latest classifications identified in the Clinical and Functional Translation of CFTR project [http://www.cftr2.org/index.php] should be used to aid with CF diagnosis. Finally, to avoid delays in treatment, we provide guidelines for presumptive diagnoses and recommend how to determine the age of diagnosis.

Phenotypes of California CF Newborn Screen-Positive Children with CFTR 5T Allele by TG Repeat Length.

BACKGROUND: At the cystic fibrosis transmembrane conductance regulator (CFTR) gene (IVS8)-(TG)m(T)n locus, a lower number of thymidines (legacy names 9T vs. 7T vs. 5T) and a higher number of (TG) repeats (TG-11 vs. 12 vs. 13) are associated with decreasing translation of functional CFTR protein in vitro. METHODS: Retrospective cohort study comparing phenotypes of California CF newborn screen-positive children (followed 2-8 years) who had two CF-causing mutations (diagnosed as CF) with those who had one mutation from a panel of 40 CF-causing mutations (CF40mut) and one (IVS8)-(TG)11, 12, or 13-5T mutation detected by sequencing (diagnosed as CFTR-related metabolic syndrome [cRMS]). RESULTS: The study included 428 children, of which 234 had two CF-causing mutations, and were used to compare with the other 194 children with one CF-causing mutation and one isolated 5T allele [CF40mut/(TG)13-5T = 21, CF40mut/(TG)12-5T = 85, and CF40mut/(TG)11-5T = 88]. Among children with CF40mut/(TG)13-5T, 38% were diagnosed with CF by 8 years, based on sweat chloride results and clinical presentation. Six percent of those with CF40mut/(TG)12-5T, and none with CF40mut/(TG)11-5T, reached diagnostic criteria. CONCLUSIONS: CFTR (IVS8)-(TG)m-5T allele (TG) tract length determination provides valuable information in predicting the risk of developing a CF phenotype. Of the three types of 5T alleles evaluated, screen-positive children with genotype CF40mut/(TG)13-5T progressed from CRMS to CF at a high rate, while there was little evidence of clinical disease in those with CF40mut/(TG)11-5T. Additional data from longer follow-up intervals are needed to fully understand the natural history of individuals with a CF40mut/(TG)m-5T genotype.

Prediction of respiratory outcome in extremely low gestational age infants.

BACKGROUND: Bronchopulmonary dysplasia (BPD) is a commonly used outcome for randomized neonatal trials. OBJECTIVES: The aim of the present study was to determine whether a diagnosis of BPD or respiratory morbidity (RM1 or RM2) at 12 months corrected age better predicted subsequent RM in extremely low gestational age infants (23-28 weeks of gestation). METHODS: Initial analysis was undertaken in a development cohort of 76 infants who underwent pulmonary function tests (PFTs) at 12 months corrected age. Parents completed infant respiratory diaries 2 weeks before the PFTs. Analysis was then undertaken in a validation cohort of 227 infants whose parents completed a 4-week respiratory diary when their infant was 12 months corrected age. BPD at 28 days (BPD28d) and 36 weeks post-menstrual age (BPD36w), RM1 (≥3 days and/or nights of cough, wheeze, and/or medicine use) and RM2 (≥4 days and/or nights of cough, wheeze, and/or respiratory medicine use) each week for 2 weeks at 12 months corrected age were assessed with regard to prediction of respiratory outcomes at 24 months documented by respiratory health questionnaires. RESULTS: BPD28d and BPD36w were not significantly associated with any respiratory outcome. Areas under the receiver operating characteristic curves were significantly better for either definition of RM than BPD28d or BPD36w for all outcomes. CONCLUSIONS: RM documented by parental completed diaries at 12 months corrected age better predicted respiratory outcome at 24 months corrected age than BPD regardless of diagnostic criteria.

Low urine vascular endothelial growth factor levels are associated with mechanical ventilation, bronchopulmonary dysplasia and retinopathy of prematurity.

BACKGROUND: Organ-specific vascular endothelial growth factor (VEGF) expression is decreased during the pathogenesis of bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) several weeks before either disease can be diagnosed. Early measurement of organ-specific tissue VEGF levels might allow identification of infants at high risk for these diseases, but is not clinically feasible. Urine VEGF is easily measured and useful in early diagnosis of several diseases. OBJECTIVES: Our aims were to assess the correlation of urine VEGF levels measured in the first postnatal month with subsequent BPD or ROP diagnosis and to determine whether various infant characteristics influence urine VEGF levels. METHODS: 106 subjects born at <29 weeks' gestation and surviving to 36 weeks' postmenstrual age were selected from an existing database and biorepository. Urine VEGF and total protein were measured in 2-3 samples per subject. RESULTS: Urine VEGF/protein levels increased by 72% per week (p < 0.0001) during the first postnatal month. In multivariable analysis controlling for postnatal age, lower VEGF/protein was associated with higher levels of mechanical respiratory support (p = 0.006), male gender (p = 0.001) and early sepsis (p = 0.003) but not with fraction of inspired oxygen. Lower urine VEGF/protein and mechanical ventilation were each associated with BPD and ROP. In analyses adjusted for respiratory support, lower urine VEGF/protein and ROP remained associated but urine VEGF/protein and BPD did not. CONCLUSIONS: Low urine VEGF/protein levels in the first postnatal month are associated with mechanical ventilation, BPD, and ROP.

Reduction of retinopathy of prematurity in extremely low gestational age newborns treated with recombinant human Cu/Zn superoxide dismutase.

BACKGROUND: Reactive oxygen species have been implicated in the pathogenesis of retinopathy of prematurity (ROP). Extremely low gestational age (GA) newborns (ELGANs) have the highest risk of ROP and might benefit most from treatment with antioxidants. OBJECTIVES: To determine whether recombinant human Cu/Zn superoxide dismutase (rhSOD) decreases the incidence or severity of ROP in ELGANs. METHODS: A previous multicenter trial of intratracheal rhSOD for prevention of bronchopulmonary dysplasia randomized 302 preterm infants to receive intratracheal rhSOD or placebo at birth and every 48 h for 1 month. An analysis of the incidence and severity of ROP was performed in ELGANs. RESULTS: The risk of ROP increased with decreasing GA. Within the entire cohort, no significant differences in ROP were found in the placebo versus rhSOD groups. Subgroup analysis on infants born at <26 weeks (n = 72) revealed a 22% reduction in ROP from 85% (placebo) to 66% (rhSOD) (p = 0.06). In subjects born at <25 weeks (n = 24), ROP was reduced by 53% from 85% (placebo) to 40% (rhSOD) (p = 0.03). ROP severity above stage 2 was found in 42% of placebo-treated infants but only 25% of rhSOD-treated subjects with ROP. CONCLUSIONS: This post hoc analysis suggests that rhSOD reduces the risk of developing ROP in ELGANs, although further studies are required to confirm this observation.

Update on the diagnosis and management of bronchopulmonary dysplasia/chronic lung disease of infancy: what the radiologist should know.

Pediatric radiologists are frequently called upon to render interpretations of chest radiographs performed on premature infants with chronic respiratory problems. After the acute phase of surfactant deficiency (respiratory distress syndrome), infants with persistent respiratory problems are loosely categorized by clinicians as evolving toward a broad, rather vague entity called bronchopulmonary dysplasia (BPD) or chronic lung disease (CLD). This review aims to update the radiologist on how the characteristics of the disease have shifted and how management, diagnosis and pathology have changed since the disorder was first described more than 40 years ago. The radiologist armed with this information might be better prepared to provide insightful reporting and address the needs of the neonatologist.

US assessment of estrogen-responsive organ growth among healthy term infants: piloting methods for assessing estrogenic activity.

BACKGROUND: A mother's circulating estrogen increases over the third trimester, producing physiological effects on her newborn that wane postnatally. Estrogenization might be prolonged in newborns exposed to exogenous estrogens, such as isoflavones in soy formula. OBJECTIVE: We evaluated ultrasonography for monitoring growth of multiple estrogen-responsive organs in healthy infants and developed organ-growth trajectories. MATERIALS AND METHODS: We studied 38 boys (61 visits) from birth to age 6 months and 41 girls (96 visits) from birth to age 1 year using a partly cross-sectional, partly longitudinal design. We measured uterus and ovaries in girls, testes and prostate in boys, and kidneys, breasts, thymus, and thyroid in all children. We imaged all organs from the body surface in one session of < 1 h. RESULTS: Uterine volume decreased from birth (P < 0.0001), whereas ovarian volume increased sharply until age 2 months and then decreased (P < 0.001). Testicular volume increased with age (P < 0.0001), but prostatic volume showed minimal age trend. Breast bud diameter showed no age trend in girls but declined from birth in boys (P = 0.03). CONCLUSION: US examination of multiple estrogen-responsive organs in infants in a single session is feasible and yields volume estimates useful for assessing potential endocrine disruptor effects on organ growth.

Cystic fibrosis newborn screening: using experience to optimize the screening algorithm.

Newborn screening (NBS) for cystic fibrosis (CF) offers the opportunity for early diagnosis and improved outcomes in patients with CF and has been universally available in the state of Massachusetts since 1999 using an immunoreactive trypsinogen (IRT)-DNA algorithm. Ideally, CF NBS is incorporated as part of an integrated NBS system that allows for comprehensive and coordinated education, laboratory screening, clinical follow-up, and evaluation so that evidence-based data can be used to maximize quality improvements and optimize the screening algorithm. The New England Newborn Screening Program (NENSP) retrospectively analyzed Massachusetts's CF newborn screening data that yielded decisions to eliminate a screen-positive category, maintain the IRT cutoff value that prompts the second tier DNA testing, and communicate CF relative risk to primary care providers (PCPs) based on categorization of positive CF NBS results.

Cystic Fibrosis Foundation practice guidelines for the management of infants with cystic fibrosis transmembrane conductance regulator-related metabolic syndrome during the first two years of life and beyond.

Through early detection, newborn screening (NBS)(1) for cystic fibrosis (CF) offers the opportunity for early intervention and improved outcomes. NBS programs screen for hypertrypsinogenemia, and most also identify mutations in the CF transmembrane conductance regulator (CFTR) gene. Individuals identified by NBS are diagnosed with CF if they have an elevated sweat chloride level or if they have inherited 2 disease-causing mutations in the CFTR gene. Mutations in the CFTR gene can cause CF, but not all CFTR mutations are disease-causing. The term CFTR-related metabolic syndrome (CRMS) is proposed to describe infants identified by hypertrypsinogenemia on NBS who have sweat chloride values <60 mmol/L and up to 2 CFTR mutations, at least 1 of which is not clearly categorized as a "CF-causing mutation," thus they do not meet CF Foundation guidelines for the diagnosis of CF. With what is now near-universal CF NBS in the United States, an increasing number of infants with CRMS are being identified. Given our inadequate knowledge of the natural history of CRMS, standards for diagnosis, monitoring, and treatment are absent. This document aims to help guide the monitoring and care of individuals with CRMS while our knowledge base on appropriate management evolves.

Cystic Fibrosis Foundation evidence-based guidelines for management of infants with cystic fibrosis.

Newborn screening for cystic fibrosis (CF) offers the opportunity for early medical and nutritional intervention that can lead to improved outcomes. Management of the asymptomatic infant diagnosed with CF through newborn screening, prenatal diagnosis, or sibling screening is different from treatment of the symptomatically diagnosed individual. The focus of management is on maintaining health by preventing nutritional and respiratory complications. The CF Foundation convened a committee to develop recommendations based on a systematic review of the evidence and expert opinion. These guidelines encompass monitoring and treatment recommendations for infants diagnosed with CF and are intended to help guide families, primary care providers, and specialty care centers in the care of infants with CF.