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At least 19 recordsLinked to original sources
PubMed2002

[Determination of total phenylalanine and galactose from a sample of dry blood on paper filter: its application on neonatal screening].

Neonatal screening programs for metabolic disorders are recommended especially for phenylketonuria and congenital hypothyroidism. The present study was designed to adapt, develop and evaluate a SUMA method for total galactose (Gal) and phenylalanine (Phe) measurement on filter paper blood specimens. A single 5 mm disk with blood was deproteinized with methanol-acetone and eluted with distilled water. Ten microliters of the extract was transferred to one well of a ultramicroELISA plate, and the reaction solution was added to determine Phe level. The remaining extract was used for the GAL determinations. The method showed good linearity in a 0-50 mg/dl concentration range for Phe and 0-60 mg/dl for Gal. The detection limit was 0.14 mg/dl for Phe and 0.9 mg/dl for Gal. Reproducibility was assessed with filter paper blood specimens containing Gal and Phe at low, middle and high levels. Intraassay coefficients of variation were 10%, 7.5%, 6.22%, and 8.5%, 7%, 5%, respectively, whereas interassay coefficients of variation were 9.54%, 6%, 7% and 6%, 4.6%, 5.6%, respectively. In 1,000 samples from newborns, four samples of Phe and two samples of Gal showed a concentration below the threshold set for each assay. This method provides a rapid means to survey for a low incidence disease (i.e., galactosaemia: incidence, 1/30,000), in existing phenylketonuria analysis programs, where an incidence of 1/10,000), easily justifies the cost of mass screening.

Blood Stains↗
PubMed2003

Direct tandem mass spectrometric analysis of amino acids in dried blood spots without chemical derivatization for neonatal screening.

Neonatal screening performed by electrospray tandem mass spectrometry is a powerful technique in clinical diagnostics. In the present paper an alternative to the widely accepted method involving butylation has been developed. In the new method butylation is not required, and multiple reaction monitoring (MRM) was used instead of constant neutral loss scanning. The method was optimized for detection of 23 L-amino acids in their native form. Quantitation was based on isotope-labeled internal standards, calibration curves were linear from 0 to 500 micromol/L, and detection limits were in the range 2-42 micrmol/L. The utility of the present technique is illustrated in the case of one neonate suffering from citrullinaemia.

Amino Acid Metabolism, Inborn Errors↗
PubMedDate not supplied

Neonatal screening.

Neonatal screening (NS) is a medical act in the context of preventive medicine aimed at the early identification of infants affected by certain conditions that threaten their life and long-term health, for which a timely intervention can lead to a significant reduction of morbidity, mortality and associated disabilities. It emerged three decades ago in the context of prevention of mental retardation. Since then, around 600 inborn metabolic disorders have been described and technological progress has been impressive; nevertheless only around 5% of the disorders have been the object of NS. The most frequently cited reasons for the limitation are low prevalence and the lack of treatment. The tandem mass spectrometry has come in place in recent years across the globe, expanding NS to include several disorders of intermediary metabolism. This has shown, in addition to a prevalence much higher than previously thought, the benefits of early detection. The present work is a review of NS, not only from the point of view of technological/medical achievements, but also considering other factors which will affect specific disease selection, according to the social and organizational infrastructure that may expand the borders of NS.

Forecasting↗
PubMed2003

Comparing the clinical evolution of cystic fibrosis screened neonatally to that of cystic fibrosis diagnosed from clinical symptoms: a 10-year retrospective study in a French region (Brittany).

Until the year 2000, systematic cystic fibrosis (CF) neonatal screening was only performed in a few regions of France. The Brittany region began in 1989, but not the neighboring region of Loire-Atlantique. The present study compares the clinical evolution of both affected populations 10 years after screening was started. Although the 77 screened and 36 nonscreened children were followed in different CF centers, they were included in similar care protocols. The clinical characteristics at diagnosis and their evolution over a 10-year period of all the children affected with CF and born between January 1, 1989 and December 31, 1998, excluding those with meconium ileus, were compared. There were no significant differences in sex ratio, gestational age, anthropometric data at birth, frequency of deltaF508 homozygotes, proportion of pancreatic-insufficient patients, and mean age between the two populations. Age at diagnosis was lower in the screened group (38 days vs. 472 days, P < 10(-7)), as was the delay in supplementation with pancreatic enzymes (1.7 months vs.15.9 months, P < 10(-7)). The proportion of children who were hospitalized at least once was higher among the nonscreened than the screened patients (86% vs. 49%, P < 10(-4)). Z-scores for weight and height were significantly better in the screened population, not only in the first years of life, but also at 5 years old for height and 8 years old for weight. The Shwachman and Brasfield scores were higher among the screened children during the whole period of follow-up. No significant differences in colonization by Pseudomonas aeruginosa nor in lung function were found. Given the homogeneity in the characteristics and the follow-up of both populations, the benefits in terms of nutrition and clinical well-being of neonatal screening appear to be clear, thus confirming the advantages of its general implementation.

Age of Onset↗
PubMed1982

[Value of neonatal screening for cystic fibrosis. Evaluation of a neonatal screening program including 34,522 neonates (author's transl)].

Screening for cystic fibrosis in 34,522 neonates was done by assaying proteolytic activity in feces samples spread on special filter paper. Infants were considered at high risk for cystic fibrosis if proteolytic activity was significantly decreased and albumin was found in all the fresh stool specimens. Cystic fibrosis was detected in eight infants, most of whom were already hospitalized for respiratory and/or digestive manifestations suggestive of the disease. Six other patients, one of whom was three-and-a-half years-old, were detected after referral by pediatricians. Two false-negative results were recorded, in infants without detectable pancreatic involvement. Given these results, the authors believe that routine neonatal screening for cystic fibrosis is unnecessary. The various etiopathogenetic mechanisms and the possibilities for investigating patients with cystic fibrosis are discussed.

Clinical Enzyme Tests↗
PubMed1999

Technical aspects of neonatal screening using tandem mass spectrometry. Report from the 4th meeting of the International Society for Neonatal Screening.

Quantitative analysis of amino acids (AA) and acylcarnitines using tandem mass spectrometry is an emerging technology used to screen neonatal dried blood spot samples for disorders in the metabolism of AA, organic acids and fatty acids. This paper provides a brief review of some of the technically oriented issues which emerged at the 4th meeting of the International Society for Neonatal Screening in Stockholm, 1999. The information covers sample preparation, instrumentation, data acquistion modes, internal standards, interpretation, confounding factors and practical screening experience.

Amino Acid Metabolism, Inborn Errors↗
PubMed1997

Nutritional benefits of neonatal screening for cystic fibrosis. Wisconsin Cystic Fibrosis Neonatal Screening Study Group.

BACKGROUND: Many patients with cystic fibrosis are malnourished at the time of diagnosis. Whether newborn screening and early treatment may prevent the development of a nutritional deficiency is not known. METHODS: We compared the nutritional status of patients with cystic fibrosis identified by neonatal screening or by standard diagnostic methods. A total of 650,341 newborn infants were screened by measuring immunoreactive trypsinogen on dried blood spots (from April 1985 through June 1991) or by combining the trypsinogen test with DNA analysis (from July 1991 through June 1994). Of 325,171 infants assigned to an early-diagnosis group, cystic fibrosis was diagnosed in 74 infants, including 5 with negative screening tests. Excluding infants with meconium ileus, we evaluated nutritional status for up to 10 years by anthropometric and biochemical methods in 56 of the infants who received an early diagnosis and in 40 of the infants in whom the diagnosis was made by standard methods (the control group). Pancreatic insufficiency was managed with nutritional interventions that included high-calorie diets, pancreatic-enzyme therapy, and fat-soluble vitamin supplements. RESULTS: The diagnosis of cystic fibrosis was confirmed by a positive sweat test at a younger age in the early-diagnosis group than in the control group (mean age, 12 vs. 72 weeks). At the time of diagnosis, the early-diagnosis group had significantly higher height and weight percentiles and a higher head-circumference percentile (52nd, vs. 32nd in the control group; P=0.003). The early-diagnosis group also had significantly higher anthropometric indexes during the follow-up period, especially the children with pancreatic insufficiency and those who were homozygous for the deltaF508 mutation. CONCLUSIONS: Neonatal screening provides the opportunity to prevent malnutrition in infants with cystic fibrosis.

Body Height↗
PubMed2003

Methodological factors involved in neonatal screening using transient-evoked otoacoustic emissions and automated auditory brainstem response testing.

The methodological factors involved in screening neonates for hearing loss, using transient-evoked otoacoustic emissions (TEOAEs) and automated auditory brainstem responses, have been evaluated from a large sample of neonates. The risk factors, commonly used to select babies for a targeted screen, have very little correlation with failing TEOAE testing. The parameters used to determine passing or failing the TEOAE test and the false alarm rate change markedly with age in the first few days of life as, of course, did the percentage of babies who failed the test. The stimulus level used was the default setting for the Otodynamics equipment but the stimulus level measured in the ear canal decreased over the first 140 h of life. It is thought that this reflects the impedance changes in outer and middle ears and possible changes in middle ear dynamics. The methodological variables investigated here can illuminate some of the differences in previous reports of neonatal screening, in particular the reported hit and false alarm rates.

Age Factors↗
PubMed1993

Cost-effectiveness of neonatal screening for Duchenne muscular dystrophy--how does this compare to existing neonatal screening for metabolic disorders?

Costs of screening a series of 18,152 newborn males for Duchenne muscular dystrophy (DMD) in Canada were evaluated. The final aim of neonatal screening for DMD is the avoidance of additional cases in the families identified. Total costs to avoid one case of DMD were estimated at Cdn. $172,000, while the incremental costs were found to be $83,000. Reagent costs, test sensitivity, efficacy of screening and compliance with genetic advice were identified as factors crucial for cost-effectiveness. Costs of neonatal screening for DMD are compared with costs of neonatal screening for inborn metabolic disorders. It is found that the two programmes are similar in costs. Earlier predictions of inordinate costs of screening for DMD are refuted.

Cost-Benefit Analysis↗
PubMed1999

Controlled trial of universal neonatal screening for early identification of permanent childhood hearing impairment: coverage, positive predictive value, effect on mothers and incremental yield. Wessex Universal Neonatal Screening Trial Group.

OBJECT: Congenital bilateral permanent childhood hearing impairment (PCHI) impairs communication skills and, in some cases, mental health and employment prospects. Management of PCHI within the first year of life can alleviate most of its adverse effects. We investigated whether neonatal screening of all babies born in hospital, in addition to the standard Health Visitor Distraction Test (HVDT), would increase the rates of early diagnosis. METHODS: Between 1993 and 1996, two teams of four part-time testers and equipment moved between two pairs of hospitals to achieve four periods with neonatal screening and four without neonatal screening, each of 4-6 mo duration in each hospital. Babies did or did not undergo neonatal screening dependent on the periods during which they were born. We used a transient evoked oto-acoustic emissions (TEOAE) test followed, in infants who failed this test, by an automated auditory brainstem response (AABR) test on the same day. We referred babies with positive results for audiological assessment. RESULTS: 53,781 infants were included in the trial, including 25,609 born during periods of neonatal screening. The neonatal screen achieved 87% coverage of inborn births, with a false alarm rate of 1.5%, and an overall yield from the screen of 90 cases of bilateral PCHI > or = 40dB HTL per 100,000 target population, equivalent to 80% of the expected prevalence of the condition in the population. Seventy-one more babies with moderate or severe PCHI per 100,000 target population were referred before age 6 mo during periods with neonatal screening than during periods without. Early confirmation and management of PCHI were significantly increased. The false-negative rate of neonatal screening was significantly lower than that of HVDT screening (4% vs 27%). CONCLUSIONS: Neonatal screening is effective in identification of congenital PCHI and may be particularly useful for babies with moderate and severe PCHI for whom early management may have the most benefit.

Audiometry, Evoked Response↗
PubMed1991

Neonatal screening for sickle cell disease: a cost-effectiveness analysis.

PURPOSE: To determine the cost-effectiveness of screening newborn infants for sickle cell disease. DESIGN: We developed a decision model that examined two strategies: (1) screening neonates and administering penicillin to infants found to have sickle cell disease in the hope of preventing pneumococcal sepsis, and (2) not screening but administering penicillin to infants after symptoms of sickle cell disease develop. The model calculates the cost-effectiveness of these strategies during the first 3 years of life. We applied the model to three prototypic populations of neonates--black, nonblack with a relatively high prevalence of hemoglobin S genes, and nonblack with a low prevalence of hemoglobin S genes. DATA IDENTIFICATION: We obtained from the published literature the effectiveness and risk of penicillin prophylaxis, the risk of pneumococcal sepsis, and the probability that in infants not screened the development of symptoms would lead to the discovery of sickle cell disease within the first 3 years of life; we used the published literature and the Hardy-Weinberg law to determine the prevalence of sickle cell disease. We used actual variable costs of screening, antibiotic prophylaxis, and hospitalization for pneumococcal sepsis or anaphylaxis. RESULTS: Screening and then treating affected black infants costs only $3100 more per life saved than not screening. Screening nonblack populations with a high prevalence of hemoglobin S genes would cost $1.4 million per life saved, and screening low prevalence populations would cost $450 billion per life saved. CONCLUSIONS: Screening black infants is very worthwhile, but screening populations in which the hemoglobin S gene is rare is unjustified.

Anaphylaxis↗
PubMed1999

[Neonatal screening for sickle cell anemia in metropolitan France. For the group for neonatal screening of sickle cell anemia of the French Association for Screening and Prevention of Infant Handicaps (AFDPHE)].

An experimental neonatal screening program for sickle cell disease (SCD) was set up in continental France in 1990. The screening strategy was fine-tuned based on results of screening programs in the French West Indies and of pilot studies in several regions of continental France. Since early 1994, sickle cell disease screening is done in combination with screening for phenylketonuria, hypothyroidism, and congenital adrenal hyperplasia but is restricted to infants identified by maternity units as belonging to high-risk ethnic groups. Cost has proved acceptable, and rates of false-positive and false-negative tests have been very low. The management of infants with a positive screening test has been defined. All cases detected to date have been included in a prospective study. SCD is currently being extended to the entire country, an endeavor that will require considerable education efforts and careful surveillance.

Anemia, Sickle Cell↗
PubMed2001

Early diagnosis of cystic fibrosis through neonatal screening prevents severe malnutrition and improves long-term growth. Wisconsin Cystic Fibrosis Neonatal Screening Study Group.

OBJECTIVE: Despite its relative frequency among autosomal recessive diseases and the availability of the sweat test, cystic fibrosis (CF) has been difficult to diagnose in early childhood, and delays can lead to severe malnutrition, lung disease, or even death. The Wisconsin CF Neonatal Screening Project was designed as a randomized clinical trial to assess the benefits and risks of early diagnosis through screening. In addition, the incidence of CF was determined, and the validity of our randomization method assessed by comparing 16 demographic variables. METHODOLOGY: Immunoreactive trypsinogen analysis was applied to dried newborn blood specimens for recognition of CF risk from 1985 to 1991 and was coupled to DNA-based detection of the DeltaF508 mutation from 1991 to 1994. Randomization of 650 341 newborns occurred when their blood specimens reached the Wisconsin screening laboratory. This created 2 groups-an early diagnosis, screened cohort and a standard diagnosis or control group. To avoid selection bias, we devised a unique unblinding method with a surveillance program to completely identify the control subjects. Because sequential analysis of nutritional outcome measures revealed significantly better growth in screened patients during 1996, we accelerated the unblinding and completely identified the control group by April 1998. Having each member of this cohort enrolled and evaluated for at least 1 year and having completed a comprehensive surveillance program, we performed another statistical analysis of anthropometric evaluated indices that includes all CF patients without meconium ileus. RESULTS: The incidence of classical CF, ie, patients diagnosed in this trial with a sweat chloride of 60 mEq/L greater, was 1:4189. By incorporating other CF patients born during the randomization period, including 2 autopsy diagnosed patients and 8 probable patients, we calculate a maximum incidence of 1:3938 (95% confidence interval: 3402-4611). Although there were group differences in the proportion of patients with DeltaF508 genotypes and with pancreatic insufficiency, validity of the randomization plan was demonstrated by analyzing 16 demographic variables and finding no significant difference after adjustment for multiple comparisons. Focusing on patients without meconium ileus, we found a marked difference in the mean +/- standard deviation age of diagnosis for screened patients (13 +/- 37 weeks), compared with the standard diagnosis group (100 +/- 117). Anthropometric indices of nutritional status were significantly higher at diagnosis in the screened group, including length/height, weight, and head circumference. During 13 years of study, despite similar nutritional therapy and the inherently better pancreatic status of the control group, analysis of nutritional outcomes revealed significantly greater growth associated with early diagnosis. Most impressively, the screened group had a much lower proportion of patients with weight and height data below the 10th percentile throughout childhood. CONCLUSIONS: Although the screened group had a higher proportion of patients with pancreatic insufficiency, their growth indices were significantly better than those of the control group during the 13-year follow-up evaluation and, therefore, this randomized clinical trial of early CF diagnosis must be interpreted as unequivocally positive. Our conclusions did not change when the height and weight data before 4 years of age for the controls detected by unblinding were included in the analysis. Also, comparison of growth outcomes after 4 years of age in all subjects showed persistence of the significant differences. Therefore, selection bias has been eliminated as a potential explanation. In addition, the results show that severe malnutrition persists after delayed diagnosis of CF and that catch-up may not be possible. We conclude that early diagnosis of CF through neonatal screening combined with aggressive nutritional therapy can result

Cystic Fibrosis↗
PubMed1999

Biological specimen banks in neonatal screening.

The Danish neonatal screening program analyses dried blood spot samples (DBSS) from close to 70,000 newborns annually from Denmark, Greenland and the Faroe Islands. Since 1982, all DBSS have been stored in a biological specimen bank at -20 degrees C as a routine procedure after analysis. Before sampling, parents are given written information about the screening tests, the biobank and its use, and can choose to opt out. Since 1993 the biobank has been regulated by specific legislation, and thus assumes a unique position among biological specimen banks. Its purposes are: (i) diagnosis and treatment of diseases screened for, including repeat testing, quality assurance and group statistics; (ii) other diagnostic uses during infancy; and (iii) research projects. The stored samples have been used successfully to diagnose a range of genetic diseases using biochemical and molecular genetic assays, and to diagnose congenital CMV and toxoplasmosis infections using assays for specific IgM antibodies and pathogen nucleic acids. The unbiased nature and comprehensive coverage of the samples in the biobank make them attractive for research purposes. Our studies have focused on the epidemiology of genetic disease alleles and other molecular disease markers and on retrospective screening projects, which have allowed rapid appraisal of the performance of novel screening modalities, saving years of prospective screening trials. Storage of neonatal screening samples is thus beneficial not only to the individual testees, but also to future generations of newborns.

Biological Specimen Banks↗
PubMed1986

[Neonatal screening for congenital adrenal hyperplasia due to 21-hydroxylase deficiency. 1. Enzyme immunoassay of dried blood 17 alpha-hydroxyprogesterone and its application to neonatal screening for congenital adrenal hyperplasia].

An enzyme immunoassay for measuring 17 alpha-hydroxyprogesterone (17-OHP) in dried blood collected on filter paper has been developed. The method is easy and rapid and has specificity, accuracy and precision. 17-OHP values of neonates with congenital adrenal hyperplasia (CAH, 40 ng/ml) were extremely high compared with normal neonates (1.1 +/- 0.7 ng/ml). There was a negative correlation between the 17-OHP value and birth weight. The method has been applied to neonatal screening for CAH due to 21-hydroxylase deficiency. During 38 months, 67,392 neonates were screened. The recall rate and the medical evaluation rate were 1.16% and 0.09%, respectively. A third of recalled neonates were low birth weight infants. 5 neonates were proven to have CAH, and its incidence was 1:13,478. The present study demonstrates the feasibility of a neonatal screening for CAH and indicates that the frequency of CAH may be greater than previously reported by case assessment method in Japan.

17-alpha-Hydroxyprogesterone↗