Clinical complications in children with false-negative results in cystic fibrosis newborn screening

Abstract Objective: To present signs and symptoms and clinical course in cystic fibrosis patients with false-negative newborn screening (CF NBS). Materials and methods: All children presented in this paper were covered by CF NBS. The group of 1.869.246 newborns was screened in the Institute of Mother and Child in Warsaw within a period of 01.01.1999 - 31.05.2019. Screening protocols evolved over time from IRT/IRTto IRT/DNA/EGA. Results: The authors identified 11 patients with false-negative NBS, in whom CF was diagnosed based on clinical symptoms or the examination of siblings with positive CF NBS. In the study group, the diagnosis was made significantly later in comparison to positive CF NBS patients ranging from 2 months to 15 years of age. CF NBS strategy does not significantly affect the sensitivity of the screening. Conclusion: In the presence of clinical symptoms, additional diagnostics must be implemented, in spite of the negative screening results. At first, the sweat test should be conducted, followed by a DNA analysis of the most common mutations in the given population. The diagnostic process requires searching for CFTR mutations not typically associated with a high chloride concentration in sweat. Repetition of sweat chloride concentration enables the diagnosis in children whose initial chloride values in sweat are borderline, and no CF-causing mutations are detected. In strong clinical indications, the extension of DNA analysis (EGA) is recommended in order to identify rare CF variants. In children with meconium ileus, genetic analysis is mandatory.

Reclassifying inconclusive diagnosis after newborn screening for cystic fibrosis. Moving forward.

BACKGROUND: Newborn screening for Cystic Fibrosis (CF) is associated with situations where the diagnosis of CF or CFTR related disorders (CFTR-RD) cannot be clearly ruled out. MATERIALS/PATIENTS AND METHODS: We report a case series of 23 children with unconclusive diagnosis after newborn screening for CF and a mean follow-up of 7.7 years (4-13). Comprehensive investigations including whole CFTR gene sequencing, in vivo intestinal current measurement (ICM), nasal potential difference (NPD), and in vitro functional studies of variants of unknown significance, helped to reclassify the patients. RESULTS: Extensive genetic testing identified, in trans with a CF causing mutation, variants with varying clinical consequences and 3 variants of unknown significance (VUS). Eighteen deep intronic variants were identified by deep resequencing of the whole CFTR gene in 13 patients and were finally considered as non-pathogenic. All patients had normal CFTR dependent chloride transport in ICM. NPD differentiated 3 different profiles: CF-like tracings qualifying the patients as CF, such as F508del/D1152H patients; normal responses, suggesting an extremely low likelihood of developing a CFTR-RD such as F508del/TG11T5 patients; partial CFTR dysfunction above 20% of the normal, highlighting a remaining risk of developing CFTR-RD such as F508del/F1052V patients. The 3 VUS were reclassified as variant with defective maturation (D537N), defective expression (T582I) or with no clinical consequence (M952T). CONCLUSION: This study demonstrates the usefulness of combining genetic and functional investigations to assess the possibility of evolving to CF or CFTR-RD in babies with inconclusive diagnosis at neonatal screening.

Clinical complications in children with false-negative results in cystic fibrosis newborn screening.

OBJECTIVE: To present signs and symptoms and clinical course in cystic fibrosis patients with false-negative newborn screening (CF NBS). MATERIALS AND METHODS: All children presented in this paper were covered by CF NBS. The group of 1.869.246 newborns was screened in the Institute of Mother and Child in Warsaw within a period of 01.01.1999 - 31.05.2019. Screening protocols evolved over time from IRT/IRT to IRT/DNA/EGA. RESULTS: The authors identified 11 patients with false-negative NBS, in whom CF was diagnosed based on clinical symptoms or the examination of siblings with positive CF NBS. In the study group, the diagnosis was made significantly later in comparison to positive CF NBS patients ranging from 2 months to 15 years of age. CF NBS strategy does not significantly affect the sensitivity of the screening. CONCLUSION: In the presence of clinical symptoms, additional diagnostics must be implemented, in spite of the negative screening results. At first, the sweat test should be conducted, followed by a DNA analysis of the most common mutations in the given population. The diagnostic process requires searching for CFTR mutations not typically associated with a high chloride concentration in sweat. Repetition of sweat chloride concentration enables the diagnosis in children whose initial chloride values in sweat are borderline, and no CF-causing mutations are detected. In strong clinical indications, the extension of DNA analysis (EGA) is recommended in order to identify rare CF variants. In children with meconium ileus, genetic analysis is mandatory.

Clinical characteristics of rare CFTR mutations causing cystic fibrosis in Polish population.

INTRODUCTION: More than 2000 mutations have been identified since the discovery of the CFTR gene in 1989. However, only 346 mutations have been classified as cystic fibrosis (CF)-causing mutations. Due to the increasing number of mutations and poor correlation between the genotype and phenotype, there is an urgent need to determine the mutations that are pathogenic, nonpathogenic, or lead to variable symptoms. AIM: The aim of the study was to present the clinical characteristics of Polish patients with rare and novel CFTR mutations, with an attempt to determine the pathogenicity status of those variants. MATERIALS AND METHODS: The group included 13 patients born between September 2006 and May 2019, who underwent CF newborn screening and in whom two CFTR mutations, including at least one rare or a novel mutation, were identified. RESULTS: We identified 13 patients with mutations in both alleles of the CFTR gene, one of which was at least rare in Polish population (R289NfsX17, I618RfsX2, T682KfsX40, S1347PfsX13, W356X, E33X, dup.16,17A) or was a mutation of unknown clinical consequences (H199R, L468P, A1217E, Q359R, T1036I, W1282R). None of them were described in the CFTR2 database. In all examined patients, sweat tests were elevated. The diagnosed patients presented with a wide spectrum of clinical symptoms. Broad clinical characteristics and test results are presented. CONCLUSION: Pathogenic mutations are H199R, L468P, A1217E, Q359R, T1036I, W1282R, R289NfsX17, I618RfsX2, T682KfsX40, S1347PfsX13, W356X, E33X, dup.16,17A. Every patient with a mutation of unknown clinical consequences in one CFTR allele requires attentive follow-up.

Diagnosing cystic fibrosis in newborn screening in Poland - 15 years of experience.

UNLABELLED: Early diagnosis of cystic fibrosis (CF) made by the introduction of CF NBS (Cystic Fibrosis Newborn Screening) provides the opportunity to undertake preventive measures and provide treatment before the development of irreversible changes in the respiratory tract and other complications. CF NBS was conducted as a pilot programme in four Polish districts in the period 1999-2003. In 2006 CF NBS started again and was gradually extended across the country. The aim of this study was to show the evolution of the Polish CF NBS strategies and assess the diagnostic consequences of this programme. MATERIAL AND METHODS: The study involved children diagnosed and treated only in the IMiD Centre. The strategy in Polish CF NBS was modified over time. Firstly, the model IRT/IRT and IRT/IRT/DNA with one mutation was implemented, which was followed by IRT/DNA with a gradually expanding number of CFTR mutations (tab. I). Newborns with positive results of CF NBS were called to the CF IMiD Centre, and sweat tests were performed. The children diagnosed and children with mutations in both alleles of the CFTR gene even if at least one of them had undefined pathogenicity) were taken under IMiD Centre care. Sensitivity, specificity and positive predictive values during subsequent stages of CF NBS were calculated (tab. III). RESULTS: During the 1999-2003 pilot study 444 063 newborns underwent CF NBS and in 74 cases CF was diagnosed. 582 693 newborns were screened from September 2006 to December 2011 in four regions and 100 children were diagnosed with CF. The frequencies of CF in the Polish population in both screening periods were 1:5767 and 1:5712 respectively. Firstly, the IRT/IRT model was implemented, but the number of newborns called to the CF Centre was high - the PPV was 7.6%. In the next step CF NBS DNA analysis was used. Here sensitivity and specificity were high - nearly 100%. In the following years the number of mutations detected was expanded (including 16 most common ones in the Polish population). Due to the panel changes, the number of calls declined and the PPV (predictive positive value) improved (to 26.1%) after the application of expanded genetic analysis. Expanding the panel of mutations resulted in an increased number of carriers and observational subjects. CONCLUSIONS: IRT/DNA strategy with expanded DNA analysis provides the opportunity for earlier CF diagnosis even in children with normal sweat test values. However, this model caused frequent carrier detection and inconclusive diagnosis in comparison to IRT/IRT or IRT/IRT/DNA with a limited number of mutations. Further research and changes in Polish CF NBS are needed to increase the PPV, while preserving high sensitivity and specificity..

Meconium ileus in newborns with cystic fibrosis - results of treatment in the group of patients operated on in the years 2000-2014.

AIM: Evaluation of diagnostic and treatment procedures in children with cystic fibrosis (CF) operated on because of meconium ileus (MI). MATERIAL AND METHODS: The authors retrospectively reviewed the documentation of 10 CF newborn patients operated on in the years 2000-2014 because of MI. In prenatal ultrasound (US) examinations, suspicion of bowel abnormalities was raised in 2 cases, even though all the 10 mothers had a minimum of 3 US examinations during pregnancy. The mean gestational age of the newborns was 39.2 weeks - 36-41 weeks), their mean birth weight 3472g (2560-4550 g). Family history of CF was positive in two patients. Genetic testing was performed in all the children operated on. RESULTS: In all the children operated on, mutations in both alleles of the CFTR gene were found. Five patients were F508del homozygotic, 4 were heterozygotic for this mutation, one had another mutation. Sweat tests were positive in all the children. Abdominal distention was observed in 9 patients, vomiting and retention of gastric contents in 5. In 8 children meconium was not passed at all. 2 children passed a small amount of viscid meconium. Before the operation, rectal saline washouts were done in 5 newborns. Five patients were operated on during the first day of life, four on the second day and one on the third day of life. Intra-operatively a simple form of MI was diagnosed in 8 cases, a complicated form in 2 cases. In patients with the simple form of MI, a Bishop-Koop stoma was created after the evacuation of meconium. Two of these children needed a resection of some centimetres of dilated terminal ileum with doubtful viability. In newborns with the complicated form of MI, the treatment was individualized, always with stoma formation. The time of postoperative meconium evacuation through enterostomy ranged from 6 to 15 days. Enteral feeding was started on average on the 9th day postoperatively. The mean hospital stay was 22.9 days. In 8 children the stoma was taken out at the mean age of 19.4 months, in one patient the stoma closed spontaneously. No disturbances in electrolyte balance or excessive fluid loss, nor any body weight deficits connected with the stoma were observed. There were no complications during stoma closure. All the patients are alive. The time of observation ranges from 7 to 146 months (average 95 months). All the patients currently present respiratory symptoms, have pancreatic insufficiency and need pancreatic enzyme supplementation. Seven do not, however, have body weight and height deficits. All the children with weight and height deficits have abnormal liver function tests. During observation two patients had MI equivalent symptoms, which was resolved by conservative treatment. CONCLUSIONS: 1. In every case of intra-operative diagnosis of MI, it is necessary to perform genetic testing and sweat tests to confirm or exclude CF. 2. Mechanical intra-operative decompression of the bowel from inspissated meconium with a temporary stoma, which makes the continuation of bowel decompression possible in the postoperative period, is an effective treatment in children with MI. 3. The Bishop-Koop stoma, permitting the passage through the whole gastrointestinal tract, is a safe option. In our material, no complications of this stoma, such as stoma care problems or dyselectrolithemia were observed. 4. The decision of stoma closure in children with MI and CF should be delayed until the moment of introducing a broadened diet and should be undertaken together with a pediatrician who is a specialist in CF therapy. .

Clinical status and somatic development of patients with or without meconium ileus diagnosed through neonatal screening for cystic fibrosis.

UNLABELLED: The aim of the study was to compare the patients with abnormal result of newborn screening for cystic fibrosis (CF NBS), with or without meconium ileus (MI), in regard to their clinical status at the diagnosis and early childhood somatic development. MATERIAL AND METHODS: The survey comprised patients with abnormal results of CF NBS which was carried out during years 2006-2011. Cohort of 92 children remaining under care of Institute of Mother and Child was followed in the period 09.2006-12.2011. In our study there were two groups compared: 19 children with MI and 73 children without MI. Clinical characteristics and genotype were evaluated and biochemical tests assessing pancreatic insufficiency and hepatic dysfunction were performed at the time of diagnosis, then annual weight and height Z-scores as well as clinical status based on ShwachmanKulczycki score were collected. Cox proportional hazards regression model was used to assess the effect of MI and genotype on development of pancreatic insufficiency. RESULTS: MI was observed in 19 (20.6%) of 92 CF infants. MI and non-MI patients did not differ in respect of sex, gestational age and birth weight. The presence of severe genotype was more frequent in MI than non-MI group (94.7 and 64.4% respectively), whereas no significant difference was found in F508del mutation distribution. At the time of diagnosis inadequate weight gain and hepatic function disturbances prevailed more often in MI (68.4% and 31.6%) than non-MI group (39.7% and 9.6%). Pancreatic insufficiency was diagnosed in all children in MI group and in 76.1% of non-MI group and the risk of PI development was 2.3 (1.4-4.0) times higher in MI than in non-MI patients. MI children had smaller weight-for-age Z-score at the age of 12 months (-0.95) when compared to non-MI children (-0.13). Weight Z-scores compared at the age of 2 and 3 years as also height-for-age Z-scores did not differ significantly between groups. No statistically significant difference in clinical status according to Shwachman-Kulczycki score was found between MI and non-MI groups at the age of 12 months, 2 years and 3 years. CONCLUSIONS: Our results suggest that the history of MI in children with CF may predispose them to more severe clinical course of disease in early childhood: insufficient weight gain and liver disturbances at the time of diagnosis, higher risk of developing pancreatic insufficiency and smaller weight at the age of 12 months, although clinical status according to Shwachman-Kulczycki score did not differ from non-MI group. Patients with MI, may require more intensive care and supervision in treatment. Further research is needed to asses MI impact on development of CF children in subsequent years. .

Bilateral sweat tests with two different methods as a part of cystic fibrosis newborn screening (CF NBS) protocol and additional quality control.

Infants with positive CF newborn screening (NBS) results are called to a CF Centre for verification. Those, in whom the sweat test is elevated, undergo further medical procedures. The aim of our study was to evaluate the applicability of Nanoduct - a new system measuring sweat conductivity and giving immediate results in a CF NBS protocol. Measurements with Nanoduct were compared with the classic pilocarpine method. During 3 years 487 infants from CF NBS had both sweat tests performed on the same day, at the same CF centre. CF infants had a mean conductivity of 99.8 ± 1 8.8 mmol/L and a mean chloride concentration of 74.0 ± 18.4 mmol/L. Non-CF infants values were 29.8 ± 7.7 mmol/L and 19.2 ± 6.6 mmol/L respectively. A good correlation between both tests was found (95% confidence level (CI); r=0.87). The optimal cut off, based on follow up experience of screened children, for conductivity tests was 50 mmol/L and for chloride concentration was 34 mmol/L (no lost CF, 11 false positive) with 100% sensitivity and 97.5 % specificity. In conclusion Nanoduct is a very useful and reliable tool in CF NBS protocol, allowing more time efficient organization of the diagnostic and training procedures. Simultaneous bilateral sweat testing with two different methods (concentration and conductivity) provides an extra quality control system.

Cystic fibrosis newborn screening enables diagnosis of elder siblings of recalled infants--additional benefit.

The different clinical manifestations of cystic fibrosis, with variable intensity and timing, often delay the diagnosis of this genetic autosomal recessive disorder. Many countries have introduced newborn screening for cystic fibrosis to facilitate diagnosis prior to the development of the disease. The advantages and harms of such screening programmes are regularly reassessed. In the five families presented in this article the elder siblings of screened infants were diagnosed thanks to CF NBS. This is an example of a benefit for children not even directly covered by the screening programme, adding another CF NBS advantage to the balance.

Early decline of pancreatic function in cystic fibrosis patients with class 1 or 2 CFTR mutations.

BACKGROUND: Most cystic fibrosis (CF) patients develop steatorrhea and require pancreatic enzyme replacement therapy. However, there are few data regarding the decline of exocrine pancreatic function within the first years of life in relation to CF genotype. We assessed the decline of pancreatic function in CF infants carrying class 1 or 2 CFTR mutations who were diagnosed in a neonatal screening program. MATERIALS AND METHODS: Twenty-eight CF patients were included in the study and 27 completed the study. In all subjects, fecal pancreatic elastase-1 concentrations and fecal fat excretion were scheduled to be determined at diagnosis, at 6 months of age and subsequently at 6-month intervals. RESULTS: In all CF patients, fecal pancreatic elastase-1 concentrations of the first assay after diagnosis (3 to 4 months of age) were lower than the cut-off level for normals of <200 microg/g stool. Steatorrhea was found in 81.5% of these subjects. At the age of 6 months, all screened CF subjects had fecal pancreatic elastase-1 concentrations <100 microg/g and at the age of 12 months all were pancreatic insufficient. At that time, having proved pancreatic insufficiency in all studied subjects, we stopped the scheduled further assessment. CONCLUSION: CF patients require careful monitoring of pancreatic status from diagnosis onwards. In patients carrying class 1 or 2 CFTR mutations, pancreatic insufficiency develops in the first months of life. The proper assessment of pancreatic insufficiency and intestinal malabsorption is crucial for the early introduction of pancreatic enzymes.