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Failure to thrive: the earliest feature of cystic fibrosis in infants diagnosed by neonatal screening.

The benefits of early treatment of nutritional and respiratory problems in the CF infant and of genetic counselling for the parents are widely recognized. However, clinical diagnosis of CF is often delayed despite early onset of symptoms and the usefulness of neonatal population screening as a preventive measure is still under debate. This study analyses the clinical history of CF patients diagnosed exclusively on the basis of positive neonatal screening tests with the aim of identifying the earliest markers of the disease. We studied 103 CF infants born in north-east Italy, diagnosed following neonatal screening: assay of immunoreactive trypsin (IRT) from a heel-prick blood sample followed by a measurement of meconium lactase in cases with raised IRT. Diagnosis was confirmed by sweat test at an average age of 39 days. Eighty-one patients (79%) had symptoms strongly suggestive of CF at diagnosis, and signs and/or symptoms of pancreatic insufficiency were present in 16 of the remaining 22 cases. The most frequent symptom was growth failure (69% of infants) and of these, 44% weighed the same as at birth or less. Pancreatic insufficiency was confirmed by the low level of faecal chymotrypsin found in 85% of cases. IRT was elevated in all cases. CF had not been suspected in any symptomatic infant, although most of the infants had been monitored by a paediatrician. In conclusion, most infants with CF diagnosed by neonatal screening are already symptomatic in the first six weeks of life and the most frequent symptom is failure to thrive; pancreatic insufficiency was already present in most cases. In areas without CF neonatal screening programs, the disease should be excluded by differential diagnosis in all cases with growth failure notwithstanding adequate caloric intake in the first months of life. The high sensitivity, low cost and simple execution of IRT and fecal chymotrypsin tests make them an ideal first step in suspect cases before proceeding to the sweat test, often performed late because of limited availability.

Birth Weight↗

Neonatal screening for hearing impairment.

Over the last 25 years, technological developments have facilitated the implementation of neonatal screens for hearing impairment. Restricting tests to 10% of the cohort with risk factors enables detection of around 40% of congenital impairments. Critical review has therefore recommended universal screening targeting for identification all neonates with moderate or worse impairment. Both oto-acoustic emission and auditory brainstem response (ABR) recording make this possible. The emission test is very sensitive to mild impairments. Specificity critically depends upon the age of maternity testing, but a false positive rate of 8% at discharge is typical. This is reduced to <1% by implementing a second outpatient test, or an ABR before discharge. Both tests are required to identify auditory neuropathies. Widespread implementation will follow pilot trials that are currently being undertaken. The accurate assessment of screen positives, and appropriate habilitation for those identified, is also required. These needs are complex, and require further study if universal screening is to become routine.

Audiometry, Evoked Response↗

Neonatal screening for congenital adrenal hyperplasia in Taiwan: a pilot study.

BACKGROUND AND PURPOSE: Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder with defects in steroidogenesis. Its wide and non-specific clinical spectrum poses problems for early diagnosis. Without a screening program, affected newborns may be missed, even though they have a life-threatening illness. The purpose of this study was to survey the prevalence and phenotype of CAH in Taiwan by neonatal screening. METHODS: From March 1, 2000, to August 31, 2001, 192,687 capillary blood spots were collected nationwide. Enzyme-linked immunosorbent assay (ELISA) was used to quantitatively measure 17-hydroxyprogesterone (17-OHP) in all specimens. RESULTS: Thirteen cases of CAH (7 female and 6 male) were detected, resulting in an estimated prevalence of 1:14,822. Nine patients (69%) had salt-wasting CAH and four (31%) had simple virilizing CAH. All cases were identified before clinical diagnosis, and also before the development of adrenal crisis. CONCLUSION: This study estimated that 20 babies with CAH are born each year in Taiwan. A nationwide neonatal screening program is the only way to provide early diagnosis and prompt treatment. This would save lives and enhance the health of affected infants.

17-alpha-Hydroxyprogesterone↗

[Neonatal screening for phenylketonuria and hypothyroidism in France. A 12-year experience].

The authors report their experience in the systematic, co-ordinated and controlled neonatal screening in France: a coverage of approximately 100 per cent for several years, nearly 13 millions of tests for phenylketonuria and more than 7 millions for hypothyroidism, almost 850 phenylketonuric children and more than 1,600 patients with hypothyroidism, screened and taken care of. The frequency of phenylketonuria is estimated at 1 for 16,394 and the frequency of hypothyroidism at 1 for 4,041. They insist on the need for a strict investigation of false negatives and point out a few specific points on the care of affected children. Overall, the assessment of neonatal screening is positive since it has allowed 2,500 children, doomed to mental retardation, to have a normal growth.

Anemia, Sickle Cell↗

Neonatal hearing screening.

Neonatal hearing screening can be performed using reliable and reproducible methods. Intervention before the age of 6 months with hearing aids and appropriate educational support services will give the infant the best possible opportunity to develop language. Potential barriers to efficient implementation of a neonatal hearing screening program include access to appropriate and timely diagnostic and support services and insurance to cover the services. Without universal neonatal hearing screening, many children with hearing loss will be missed, which will have a direct negative impact on their speech, language, educational, and social development.

Hearing Disorders↗

Neonatal screening for glutaryl-CoA dehydrogenase deficiency.

Acute encephalopathic crisis in glutaryl-CoA dehydrogenase deficiency results in an unfavourable disease course and poor outcome, dominated by dystonia, feeding problems, seizures and secondary complications, and quite often leading to early death. The prerequisite for the prevention of irreversible brain damage in this disease is the detection of affected patients and initiation of treatment before the manifestation of such crisis. Apart from macrocephaly there are no signs or symptoms characteristic for this disease in presymptomatic children and, thus, they are usually missed. In some countries, implementation of extended neonatal screening programmes using electrospray ionization tandem mass spectrometry (ESI-MS/MS) allows detection of affected newborns and start of therapy before onset of neurological complications. This article summarizes recent strategies, pitfalls and shortcomings of a mass screening for glutaryl-CoA dehydrogenase deficiency using ESI-MS/MS. Furthermore, an alternative strategy, namely DNA-based neonatal screening for the Oji-Cree variant of this disease, is demonstrated. An optimization of diagnostic as well as therapeutic procedures must be achieved before GCDH deficiency unequivocally fulfills the criteria of a reliable and successful newborn screening programme.

Amino Acid Metabolism, Inborn Errors↗

Pancreatic function in infants identified as having cystic fibrosis in a neonatal screening program.

The use of the dried-blood immunoreactive-trypsin assay for the detection of cystic fibrosis in newborns has been questioned on the grounds that it may fail to identify patients with enough pancreatic function to have normal fat absorption. To investigate this possibility, we assessed pancreatic function in 78 patients identified in a neonatal screening program as having cystic fibrosis. The diagnosis of cystic fibrosis was confirmed by abnormal results on a sweat chloride test. The results of measurements of fecal fat excretion, pancreatic-stimulation tests, and estimations of the serum level of pancreatic isoamylase indicated that 29 of the 78 children (37 percent) had substantial preservation of pancreatic function. These children (median age, four years) had growth that was close to normal and comparable to growth in children with severe pancreatic insufficiency who received oral enzyme therapy. Pancreatic insufficiency subsequently developed in 6 of the 29 patients, at 3 to 36 months of age. We conclude that the serum immunoreactive-trypsin assay used in neonatal screening programs identifies patients with cystic fibrosis who have sufficient pancreatic function to have normal fat absorption and that a substantial proportion of infants identified as having cystic fibrosis are in this category.

Child, Preschool↗

[DPOAE in high-risk neonatal screening for hearing].

64 neonates under intensive care have been tested by distortion product otoacoustic emission (DPOAE) and the auditory brain stem response (ABR) to investigate the value of DPOAE as a test for hearing impairment. The DPOAE test has been found to be practical and quick to perform. The proportion of NICU infants producing a recordable DPOAE is 83.6%, and the sensitivity and specificity to the ABR result is 92.4% and 92.2%, false positive is 7.8%, false negative is 7.6% respectively. These figures are high enough and the reduction in time compared to ABR is sufficient for the DPOAE to be considered as the primary screen, firm conclusions on the sensitivity of DPOAE to long term hearing impairment await the results from larger numbers of infants and further follow up data.

Deafness↗

Laboratory integration and utilization of tandem mass spectrometry in neonatal screening: a model for clinical mass spectrometry in the next millennium.

Clinical and neonatal screening methods using a tandem mass spectrometer are clearly a model for modern laboratory testing in the new Millennium. By the year 2000, more than 1 million blood and plasma samples will have been tested in laboratories throughout the world for a battery of metabolic disorders using a tandem mass spectrometer as the primary analytical device. A tandem mass spectrometer is considered the "ultimate" analytical detector in a variety of biochemical and clinical methods because of its very high accuracy, selectivity, precision, versatility and robust nature. The ability to achieve very high and reproducible sample throughput (approximately 600 samples/instrument/24 h) has made this technology cost-effective for newborn screening. In order to reliably measure markers of inborn errors of metabolism while maintaining low costs and high efficiency, accuracy and quality, much attention needs to be placed on monitoring and maintenance of all components of the entire testing system. These components include specimen collection and sample preparation methods, analysis by LC tandem mass spectrometry, conversion of raw mass spectra (data) into clinically meaningful results (concentration), expert interpretation of these results so that the clinician can be provided with information to facilitate a diagnose, and follow-up and education so that the maximum benefits of newborn screening translate into prevention of disease symptoms or more effective treatments. Addressing each part of the whole system will produce a quality screening program that will detect a battery of disorders using tandem mass spectrometry with a disease frequency of nearly 1 in 4000 infants.

Clinical Laboratory Techniques↗

[Neonatal screening for cystic fibrosis].

OBJECTIVE: To analyze the efficiency of the method of neonatal screening for cystic fibrosis (CF) used in Castille and Leon (Spain), which is carried out with blood from Guthrie spots. MATERIAL AND METHODS: A total of 36,086 newborns were studied from January 1999 to June 2001. Immunoreactive trypsinogen (IRT) was quantified in all samples and genetic study covering 87.5 % of mutations in the CFTR gene was carried out when IRT levels were > 60 ng/mL. The sweat test was performed in all children in whom at least one mutation was detected. RESULTS: IRT values of > 60 ng/mL were found in 285 children (0.79 %). Of these, eight children (2.8 %) were diagnosed with CF and a further 11 children (3.9 %) with a negative sweat test were found to have one mutation and were thus classified as healthy carriers. To date, no false negatives have been detected. CONCLUSIONS: The two-stage screening method fulfills the required criteria. Its sensitivity is 98.5 % and the basic model can be used in other regions although genetic screening should be optimized by pilot programs to identify the local spectrum of CFTR mutations.

Cystic Fibrosis↗

A three-step molecular protocol employing DNA obtained from dried blood spots for neonatal screening for 45,X Turner syndrome.

Turner syndrome (TS) is one of the most common human chromosomal abnormalities; it is characterized by the presence of one normal X chromosome and the complete or partial loss of the second X chromosome. The early recognition of TS patients allows for adequate therapy for short stature and pubertal sex steroid substitution. We developed a cost-effective molecular diagnostic tool that can be used to identify 45,X TS patients from dried blood spots, for possible use in neonatal screening for TS. We used a three-step method for 45,X TS detection: i) DNA extraction from dried blood spot samples, ii) pre-PCR HpaII digestion (methylation-sensitive enzyme) and iii) GeneScan analysis of selected cases. DAX-1 gene amplification was used to recognize DNA integrity, and the androgen receptor gene (Xq11-12), which is both a highly polymorphic and methylated gene, was used to determine the number of X chromosome alleles. Using this three-step diagnostic procedure, we detected apparent TS in 1/304 (0.33%) samples; such individuals should be submitted to clinical examination and karyotype confirmation. The three-step 45,X TS neonatal screening protocol is a simple, reliable, fast (under 30 h) and cost-effective diagnostic tool, useful for the neonatal detection of TS.

Blood Specimen Collection↗

[Neonatal screening for hemoglobinopathies: a pilot study in Porto Alegre, Rio Grande do Sul, Brazil].

This study was conducted to establish the frequency of hemoglobinopathies among newborns undergoing screening tests for metabolic diseases at the University Hospital (Hospital de Clínicas) in Porto Alegre, Rio Grande do Sul, Brazil. Testing for abnormal hemoglobins was performed by isoelectric focusing electrophoresis on agarose gel with blood obtained by heel stick and applied to filter paper. For confirmatory testing of abnormal neonatal screening, a venopuncture blood sample was obtained from the infant and parents and then submitted to hemoglobin electrophoresis on cellulose acetate at pH 8.6 and citrate agar at pH 6.2. A total of 1,615 subjects were studied: 20 samples showed the Hb S pattern and six samples showed Hb C. Thus, frequency of the sickle cell gene was 1.2% and that of the Hb C gene was 0.4%, regardless of race or origin. These data suggest that the inclusion of universal neonatal screening for hemoglobinopathies in the ongoing projects for the detection of phenylketonuria and congenital hypothyroidism has many advantages and should be considered in health programs.

Anemia, Sickle Cell↗

Assessment of care of children with sickle cell disease: implications for neonatal screening programmes.

OBJECTIVE: To assess the quality of care provided by hospitals for young children with sickle cell disease. DESIGN: Retrospective survey. SETTING: Teaching hospital in London. PATIENTS: 31 Children (mean age 4 years 4 months, range 4 months to 7 years 5 months) born with sickle cell disease between 1978 and 1985 identified from Hospital Activity Analysis data, an outpatient diagnostic register, and registers of the haematology department. Eight had been diagnosed on neonatal screening and at least four of these had not been followed up. MAIN OUTCOME MEASURES: Aspects of quality of outpatient care (blood testing, clinic attendance, and prophylactic drug treatment) and family care (adequate support and carers' knowledge about the disease) as assessed by reviewing the notes and administering a semistructured questionnaire to the carers, in relation to a devised list of standards deemed necessary to ensure achievement of the aims of screening. RESULTS: There were 93 outpatient attendances during the previous 12 months, but 13 children had not attended at least every six months and four not at all for more than a year. Only eight children had had three of the blood tests considered to be necessary for good care; three had had none. Prophylactic treatment with penicillin and folic acid was erratic; three children with sickle cell anaemia were not receiving regular prophylactic penicillin. IMPLICATION: Diagnosis of sickle cell disease on neonatal screening must be linked with follow up to ensure optimal management.

Anemia, Sickle Cell↗

Neonatal screening for cystic fibrosis.

Two groups of patients with cystic fibrosis were compared. The screened group, detected with an improved neonatal screening assay for immunoreactive trypsin, developed fewer chest infections requiring treatment and gained more weight than the unscreened group. Early diagnosis by screening seems to affect early morbidity.

Body Weight↗

Structural characterization of abnormal hemoglobins from dried blood specimens in a neonatal screening program.

Blood specimens dried on filter paper are now widely used for neonatal screening of hemoglobinopathies. These samples are perfectly suited for electrophoresis studies and HPLC analysis. They may also be used for DNA analysis. The structural characterization of a hemoglobin variant is also possible using protein chemistry methods. After elution of the hemoglobin from the paper, the different components are fractionated by a microscale preparative isoelectric focusing. The structural modification of the abnormal hemoglobin is then determined through a series of techniques including chain separation, aminoethylation, trypsin digestion, analysis of the peptides and determination of their aminoacid composition. The efficiency of this strategy is demonstrated by the study of an alpha-chain variant (Hb Hasharon) and three beta-chain variants (Hb S, Hb D Punjab, Hb E). Unambiguous identification of the structural abnormality was obtained with samples stored for up to 18 months and with abnormal fractions amounting to only approximately 10% of the total lysate.

Chromatography, High Pressure Liquid↗

Neonatal screening for glutaric aciduria type I: strategies to proceed.

Acute encephalopathic crisis in glutaric aciduria type I results in an unfavourable disease course and poor outcome, dominated by dystonia, feeding problems, seizures and reduced life expectancy. A conditio sine qua non for the prevention of irreversible brain damage is timely diagnosis and start of therapy, i.e. before the onset of neurological disease. As there are no specific clinical signs or symptoms that allow a reliable detection of these patients before the manifestation of encephalopathic crises, neonatal screening programmes for glutaric aciduria type I have been established in some countries using analysis of glutarylcarnitine in dried blood spots by tandem mass spectrometry. This article summarizes recent strategies, pitfalls and shortcomings of mass screening for glutaric aciduria type I, focusing on the relevant risk of missing patients with a mild biochemical phenotype (i.e. low excretors). Furthermore, it evaluates a binary strategy--using glutarylcarnitine as primary variable and glutarylcarnitine/acylcarnitine ratios as secondary variable--to improve the diagnostic sensitivity and specificity of neonatal screening for glutaric aciduria type I. An optimization of diagnostic as well as therapeutic procedures must be achieved before screening for glutaric aciduria type I can be regarded as reliable and beneficial for all patients.

Amino Acid Metabolism, Inborn Errors↗

Health economic analysis of the neonatal screening program in Japan.

In Japan, a nationwide mass screening system for neonatal metabolic diseases was established in 1977. This system consisted of screening programs for five main congenital metabolic diseases, including phenylketonuria (PKU). To evaluate the efficiency of the mass screening system, a cost-benefit analysis of the screening program for PKU (as a typical case in Japan) was carried out. The costs of the detection and the treatment program were compared with the projected benefit (avoided costs) that results from prevention of the mental retardation associated with the disorders due to PKU. Costs and benefits were discounted at an annual rate of 7%. Assuming that the incidence of PKU was 1/80,500 and the total number of infants screened was 1.2 million, net benefits for the screening program were $283,000, and the cost-benefit ratio was 1:2.5. The sensitivity analysis for the incidence of PKU showed that the cost-benefit ratios exceeded one.

Cost-Benefit Analysis↗