Neonatal screening for cystic fibrosis in São Paulo State, Brazil: a pilot study

Analysis of national coverage of neonatal cystic fibrosis screening in Brazil from 2008 to 2017

INTRODUCTION

The Brazilian neonatal screening program established in 2001 included the investigation of cystic fibrosis (CF) in the phase III of the program. For this purpose, the immunoreactive trypsin (IRT) measurement was added to the newborn screening test. The purpose of National Neonatal Screening Program is to reach 100% of live births in Brazil. The aim of this study was to analyze the coverage of neonatal Screening for Cystic Fibrosis (CF) in Brazil from 2008 to 2017.

MATERIALS AND METHODS

This is an ecological study design based on data collected from the Brazilian Outpatient Information System regarding the detection of IRT as a component of the heel stick test from 2008 to 2017. Moreover, we gathered data from the Brazilian Live Birth Information System referring to live births from 2008 to 2017. We calculated the coverage of IRT measurement for every 100 live births, using the number of IRT measurement procedures as the numerator and the number of live births stratified by federative units (states), as well as by the Brazilian regions as the denominator. These regions correspond to the divisions of the national territory based on criteria such as natural, social, cultural and economic aspects.

RESULTS

From 2008 to 2017, the regions presented the following coverage medians: South (84.1%), Southeast (71.4%), Midwest (47.3%) Northeast (12.3%) and North (10.9%). In the analysis of federative units, in the years 2013 to 2017, Paraná and Distrito Federal presented the highest median of coverage (100%), while the states with the lowest median were Rio Grande do Norte (12.1%), Amazonas (16.8%) and Paraíba (27.5%). Highest coverage was found in the South region, where are located most of the states with high socioeconomic development and high supply of health services, while the lowest coverage was found in the North region, where are located manly the states with low socioeconomic development and low supply of health services. According to data from the Brazilian Ministry of Health, the universalization of neonatal screening for cystic fibrosis occurred in 2013, however, at the end of this year, most states in the North and Northeast regions had not registered IRT measurements in the Outpatient Information System.

CONCLUSION

Although the coverage of neonatal screening for CF has improved nationwide over the years of the study, the disparity in the coverage of IRT measurements at the interregional and interstate levels is notable. Systematic implementation of neonatal screening for cystic fibrosis with equity and access to the entire population is suggested, leading to a greater number of children benefiting from treatment and a better quality of life.

The first five-year evaluation of cystic fibrosis neonatal screening program in São Paulo State, Brazil

The Hospital of the Ribeirão Preto Medical School, University of São Paulo is one of the three screening centers in São Paulo State, Brazil, and has included a test for cystic fibrosis (CF) since February 6, 2010, by a court order. We evaluated the first five years of this CF-newborn screening program. The original immunoreactive trypsinogen (IRT)/IRT screening protocol was adopted in Brazil. A total of 173,571 newborns were screened, 1,922 (1.1%) of whom showed IRT1 ≥ 70ng/mL. Of these, 1,795 (93.4%) collected IRT2, with elevated results (IRT2 ≥ 70ng/mL) in 102 of them (5.2%). We identified a total of 26 CF cases during this period, including three CF cases that were not detected by the CF-newborn screening. The incidence of the disease among the screened babies was 1:6,675 newborns screened. Median age at the initial evaluation was 42 days, comparable to that of neonates screened with the IRT/DNA protocol. Almost all infants with CF already exhibited some manifestations of the disease during the neonatal period. The mutation most frequently detected in the CF cases was F508del. These findings suggest the early age at the beginning of treatment at our center was due to the effort of the persons involved in the program regarding an effective active search. Considering the false negative results of CF-newborn screening and the early onset of clinical manifestations of the disease in this study, pediatricians should be aware of the diagnosis of CF even in children with negative test.

Pilot study for cystic fibrosis neonatal screening: the Cuban experience

Background In Cuba, no screening program for cystic fibrosis (CF) has been implemented yet. The ultramicro enzyme-linked immunosorbent assay (UMELISA)® TIR NEONATAL has been developed for the measurement of immunoreactive trypsin (IRT) in dried blood spots on filter paper. The analytical performance of the kit was evaluated in the national network of laboratories. Methods Newborn dried blood samples (DBS) were evaluated in 16 laboratories. An IRT/IRT/DNA protocol was followed using a cut-off value of 50 ng/mL. The mean, median and percentiles of the distribution were calculated and a two-sample t-test with unequal variance was used for statistical analysis. Influence of perinatal factors on IRT levels was analyzed. Results From January to June 2018, 6470 newborns were studied, obtaining a mean IRT value of 12.09 ng/mL (ranging 0-358 ng/mL) and a median of 8.99 ng/mL. Fifty-two samples (0.78%) were above the cut-off level and 16 samples (0.24%) were elevated in the re-screening process. One of them was confirmed positive by molecular biology (phe508del/c.3120 + 1G > A), constituting the first newborn screened and diagnosed early in Cuba. Second DBS samples were collected on average at 14 days and processed in the laboratory at 16 days of birth. Significant differences were observed (p < 0.05) when evaluating the influence of gender, birth weight (BW) and gestational age (GA) on the IRT values. Lower IRT concentrations were found in samples processed after 10 days of collection. Conclusions The performance of UMELISA® TIR NEONATAL in the laboratories has been satisfactory; hence CF newborn screening (NBS) was extended throughout the country from January 2019.

Newborn Screening for Cystic Fibrosis in Mersin Province: Yearly Assessment of the National Program

OBJECTIVES

A national newborn screening program for cystic fibrosis (CF) was started using immunoreactive trypsinogen (IRT) test on January 1, 2015, in Turkey. We aimed to analyze the characteristics of newborn screen-positive (NBSP) infants in Mersin province.

MATERIALS AND METHODS

The data on NBSP infants were retrospectively analyzed between 2015 and 2017 from records of Mersin Women & Children's Hospital and Mersin City Training and Research Hospital.

RESULTS

A total of 82,273 newborns were screened for CF by IRT test between January 2015 and December 2017 in Mersin. Among those, 512 infants were defined as NBSP after two repeated IRT tests (IRT/IRT) (138 infants in 2015, 217 in 2016, and 157 in 2017). Sweat test was normal in the majority of infants (115 infants [83.3%] in 2015, 189 [87.1%] in 2016, and 129 [82.2%] in 2017). Overall, between 2015 and 2017, after two repeated sweat tests, 4 infants had sweat test results in the intermediate range and 9 infants had positive sweat tests. The incidence of CF for a 3-year period was approximately 1/9300 in our region. The positive predictive value of IRT test for defining CF was 1.8%, with a sensitivity of 90.0% and specificity of 99.4%.

CONCLUSION

IRT/IRT test as a newborn screening strategy provides the opportunity for earlier diagnosis and treatment of CF patients. More data are needed to understand the frequency of CF on a national level.

Cystic Fibrosis: A Simple and Customized Strategy for Genetic Screening Able to Detect Over 90% of Identified Mutated Alleles in Brazilian Newborns

INTRODUCTION

The incorporation of molecular genetic testing into cystic fibrosis (CF) screening programs increases the specificity of the diagnostic strategy and has the potential to decrease the rate of false- positive results. In this sense, our objective was to develop a genotyping assay that could detect 25 pathogenic variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene with high sensitivity and that could be incorporated into the routine of newborn screening, complementing the current existing protocol used in our public health institution.

METHODS

A mini-sequencing assay was standardized using single-base extension in a previously genotyped control sample. This strategy was validated in a Brazilian cohort of CF patients by Sanger sequencing.

RESULTS

The inclusion of the 25 variants in the current newborn screening program increased the identification rates of two alleles from 33 to 52.43% in CF patients. This new approach was able to detect a total of 37 variants, which represents 93.01% of all mutated alleles described in the last CF Brazilian Register.

CONCLUSIONS

Mini-sequencing for the simultaneous detection of 25 CFTR gene variants improves the screening of Brazilian newborns and decreases the number of inconclusive cases. This method uses minimal hands-on time and is suited for rapid screening, which reduces sample processing costs.

The Role of Extended CFTR Gene Sequencing in Newborn Screening for Cystic Fibrosis

There has been considerable progress in the implementation of newborn screening (NBS) programs for cystic fibrosis (CF), with DNA analysis being part of an increasing number of strategies. Thanks to advances in genomic sequencing technologies, CFTR-extended genetic analysis (EGA) by sequencing its coding regions has become affordable and has already been included as part of a limited number of core NBS programs, to the benefit of admixed populations. Based on results analysis of existing programs, the values and challenges of EGA are reviewed in the perspective of its implementation on a larger scale. Sensitivity would be increased at best by using EGA as a second tier, but this could be at the expense of positive predictive value, which improves, however, if EGA is applied after testing a variant panel. The increased detection of babies with an inconclusive diagnosis has proved to be a major drawback in programs using EGA. The lack of knowledge on pathogenicity and penetrance associated with numerous variants hinders the introduction of EGA as a second tier, but EGA with filtering for all known CF variants with full penetrance could be a solution. The issue of incomplete knowledge is a real challenge in terms of the implemention of NBS extended to many genetic diseases.

Results of the Andalusian Cystic Fibrosis Neonatal Screening Program, 5 Years After Implementation

INTRODUCTION

Cystic fibrosis neonatal screening (CFNS), based on double determination of immunoreactive trypsinogen ([IRT] [IRT1/IRT2]), has been available in Andalusia since May 2011. If screening is positive, a sweat test is performed, and if that is positive or inconclusive, genetic testing is requested.

OBJECTIVE

To analyze CFNS, based on results from the first 4.5 years of the program.

MATERIALS AND METHODS

Prospective descriptive study of neonates undergoing CFNS. IRT levels, sweat chloride, and mutations were recorded. Statistical analysis was performed using SPSS 12.0.

RESULTS

Between May 2011 and December 2016, 474,953 neonates underwent CFNS. Of these, 1,087 (0.23%) had elevated IRT2. Since CFNS was introduced, 73 cases of cystic fibrosis were diagnosed; 60 were diagnosed by positive CFNS, and 13 were diagnosed by other means. In one case, the patient developed a typical clinical picture of cystic fibrosis, but had not undergone CFNS at the decision of the parents; the remaining 12 had a negative CFNS (false negatives). Of these, one patient was diagnosed before symptoms developed, as his twin brother had a positive CFNS result; another had chloride at the upper limit of normal, and was subsequently diagnosed with genetic testing before symptoms appeared; and 10 patients developed clinical signs and symptoms. Excluding patients with meconium ileus, sensitivity and specificity of the CFNS program were 85.71% and 99.78%, respectively. The incidence of the disease in Andalusia is 1/6,506 live births.

CONCLUSION

These results are a basis for reflection on possible areas for improvement of the CFNS algorithm, and thought may be given to the introduction of genetic studies to increase sensitivity and reduce false positives.

Newborn cystic fibrosis screening in southeastern Mexico: Birth prevalence and novel CFTR gene variants

Objective

To use the results of the first five years of a cystic fibrosis newborn screening program to estimate the cystic fibrosis birth prevalence and spectrum of cystic fibrosis transmembrane conductance regulator ( CFTR) gene variants in Yucatan, Mexico.

Methods

Screening was performed from 2010 to 2015, using two-tier immunoreactive trypsinogen testing, followed by a sweat test. When sweat test values were >30 mmol/L, the CFTR gene was analyzed.

Results

Of 96,071 newborns screened, a second sample was requested in 119 cases. A sweat test was performed in 30 newborns, and 9 possible cases were detected (seven confirmed cystic fibrosis and two inconclusive). The most frequently detected CFTR pathogenic variant (5/14 cystic fibrosis alleles, 35.7%) was p.(Phe508del); novel p.(Ala559Pro) and p.(Thr1299Hisfs*29) pathogenic variants were found.

Conclusions

Cystic fibrosis birth prevalence in southeastern Mexico is 1:13,724 newborns. Immunoreactive trypsinogen blood concentration is influenced by gestational age and by the time of sampling. The spectrum of CFTR gene variants in Yucatan is heterogeneous.

Measurements of Functional Responses in Human Primary Lung Cells as a Basis for Personalized Therapy for Cystic Fibrosis

Background

The best investigational drug to treat cystic fibrosis (CF) patients with the most common CF-causing mutation (F508del) is VX-809 (lumacaftor) which recently succeeded in Phase III clinical trial in combination with ivacaftor. This corrector rescues F508del-CFTR from its abnormal intracellular localization to the cell surface, a traffic defect shared by all Class II CFTR mutants. Our goal here is to test the efficacy of lumacaftor in other Class II mutants in primary human bronchial epithelial (HBE) cells derived from CF patients.

Methods

The effect of lumacaftor was investigated in primary HBE cells from non-CF and CF patients with F508del/F508del, A561E/A561E, N1303K/G542X, F508del/G542X and F508del/Y1092X genotypes by measurements of Forskolin plus Genistein-inducible equivalent short-circuit current (I_{eq-SC-Fsk + Gen}) in perfused open-circuit Ussing chambers. Efficacy of corrector C18 was also assessed on A561E/A561E and F508del/F508del cells.

Results

Our data indicate that A561E (when present in both alleles) responds positively to lumacaftor treatment at equivalent efficacy of F508del in primary HBE cells. Similarly, lumacaftor has a positive impact on Y1092X, but not on N1303K. Our data also show that cells with only one copy of F508del-CFTR respond less to VX-809. Moreover, there is great variability in lumacaftor responses among F508del-homozygous cells from different donors. Compound C18 failed to rescue A561E-CFTR but not in F508del-CFTR, thus plausibly it has a different mechanism of action distinct from lumacaftor.

Conclusions

CF patients with A561E (and likely also those with Y1029X) can potentially benefit from lumacaftor. Moreover, the methodology used here exemplifies how ex vivo approaches may apply personalized therapies to CF and possibly other respiratory diseases.

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A561E and Y1092X CFTR mutations (but not N1303K) respond positively to lumacaftor treatment.

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One copy of F508del-CFTR responds less to lumacaftor than 2 copies and F508del-responses vary greatly.

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CF patients with A561E (and likely also those with Y1029X) can potentially benefit from lumacaftor.

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The methodology used here exemplifies how ex vivo approaches may apply personalized therapies to CF and possibly other respiratory diseases.

Profile of cystic fibrosis in a single referral center in Egypt

It was generally believed that Cystic fibrosis (CF) is rare among Arabs; however, the few studies available from Egypt and other Arabic countries suggested the presence of many undiagnosed patients. The aim of the present study was to determine the frequency of CF patients out of the referred cases in a single referral hospital in Egypt. A total of 100 patients clinically suspected of having CF were recruited from the CF clinic of the Allergy and Pulmonology Unit, Children's Hospital, Cairo University, Egypt, throughout a 2 year period. Sweat chloride testing was done for all patients using the Wescor macroduct system for collection of sweat. Quantitative analysis for chloride was then done by the thiocyanate colorimetric method. Patients positive for sweat chloride (⩾60 mmol/L) were tested for the ΔF508 mutation using primer specific PCR for cystic fibrosis transmembrane conductance regulator (CFTR) gene. Thirty-six patients (36%) had a positive sweat chloride test. The main clinical presentations in patients were chronic cough in 32 (88.9%), failure to thrive in 27 (75%), steatorrhea in 24 (66.7%), and hepatobiliary involvement in 5 (13.9%). Positive consanguinity was reported in 50% of CF patients. Thirty-two patients were screened for ΔF508 mutation. Positive ΔF508 mutation was detected in 22 (68.8%) patients, 8 (25%) were homozygous, 14 (43.8%) were heterozygous, and 10 (31.3%) tested were negative. CF was diagnosed in more than third of patients suspected of having the disease on clinical grounds. This high frequency of CF among referred patients indicates that a high index of suspicion and an increasing availability of diagnostic tests lead to the identification of a higher number of affected individuals.

Newborn screening for cystic fibrosis in Serbia: a pilot study

BACKGROUND

We performed a pilot study of neonatal screening for cystic fibrosis (CF) in order to introduce it to the national screening program in Serbia.

METHODS

Immunoreactive trypsinogen (IRT) concentrations were analyzed in dried blood spot samples. Patients were recalled for repeated measurements in case of high IRT levels. Persisting high IRT levels resulted in DNA testing for the 29 most common mutations in the CF transmembrane regulator (CFTR) gene (IRT/IRT/DNA method). Sweat chloride measurements and clinical assessment were further performed for newly diagnosed patients.

RESULTS

Of 1000 samples, three were initially positive and were further analyzed for the presence of the most common CFTR mutations in the Serbian population. DNA analysis revealed two patients being homozygous for F508del mutation. One sample was false positive, as the genetic test proved to be negative and associated with normal sweat chloride concentration and unremarkable clinical presentation.

CONCLUSIONS

The results of our pilot study justified the expanding of the routine neonatal screening program in Serbia with CF. Data could be used in future in order to obtain accurate incidence of CF and carrier prevalence in our country.