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PubMed2001

Analysis of guanidinoacetate and creatine by isotope dilution electrospray tandem mass spectrometry.

Guanidinoacetate methyltransferase (GAMT) deficiency is a disorder of creatine metabolism characterized by low plasma creatine concentrations in combination with elevated guanidinoacetate (GAA) concentrations. Although rare, GAMT deficiency has been identified in children with seizures, extrapyramidal movements, developmental delay, myopathies and behavioral abnormalities. Treatment with creatine monohydrate has been proven to be effective. We describe an isotope dilution electrospray tandem mass spectrometry (ES-MS/MS) assay for the simultaneous determination of plasma GAA and creatine using multiple reaction monitoring (MRM), d(3)-creatine as the internal standard and derivatization of GAA and creatine as butyl-esters. We analysed plasma of 16 healthy adults and 20 healthy children as well as three affected children. Plasma GAA concentrations were 5.02+/-1.84 micromol/l (mean+/-S.D.) in adults, 3.91+/-0.76 micromol/l in children age 5-10 years and 11.57, 15.16, 14.36 micromol/l in children with GAMT deficiency. Plasma creatine concentrations were 34.7+/-15.25 micromol/l in adults, 58.96+/-22.30 micromol/l in children and 5.37, 8.15, 403.5 micromol/l in two untreated children and one treated child with GAMT deficiency, respectively. GAA can also be reliably measured from filter cards, which is sufficient to make the correct diagnosis while creatine is consistently falsely elevated probably secondary to liberation of red cell creatine. In nine healthy newborn infants, GAA concentrations from filter cards were 4.83+/-1.43 and 5.04+/-1.84 micromol/l in 16 healthy adults. We conclude that isotope dilution ES-MS/MS is ideal for rapid high-throughput diagnosis of GAMT deficiency both from plasma and filter paper cards. Using this technique neonatal screening is feasible for this treatable inborn error of creatine metabolism.

Adult↗

PubMed1997

[Prevalence of gallstones in the neonatal period].

AIM: To assess the prevalence of gallstones in normal neonates. METHOD: We used sonography to assess the gallbladder in 3500 unselected infants between 1993 and 1995. Examination was performed during the first four days of life as part of a prospective neonatal screening study evaluating hip and renal abnormalities. RESULTS: We found sludge or gallstones in 19 children (0.5%). In 4 of 11 patients followed for up to 18 months, the gallstones persisted. In 3 of the cases, there was a family history of gallstones. None of the children had signs of cholestasis. Three were treated with ursodesoxycholic acid 15-20 mg/kg (per day): only one responded. CONCLUSION: About 0.5% of neonates have gallstones or gall bladder sludge; this is a higher percentage than previously thought. In one-third of the patients who were followed, the gallstones remained. Persistence was more likely in those with a positive family history for gallstones.

Cholelithiasis↗

PubMed2005

X-linked adrenoleukodystrophy: therapeutic approaches to distinct phenotypes.

X-linked adrenoleukodystrophy (X-ALD) in males can present with eight distinct phenotypes, which vary greatly in respect to phenotypic expression, age of onset and rate of progression and therapy. The plasma very long chain fatty acid assay permits precise diagnosis and is already abnormal at birth. The clinical features, molecular biology, pathogenesis, and therapeutic approaches, including the indications for Hematopoietic Stem Cell Transplants (HCT) and dietary therapy are discussed, with emphasis on the asymptomatic, childhood cerebral, and adrenomyeloneuropathy phenotypes. The rationale for neonatal screening and the profound effect that such screening would have on the therapy of X-ALD, including the role of HCT, are discussed.

Adolescent↗

PubMed2005

Hemoglobinopathies in newborns from Salvador, Bahia, Northeast Brazil.

Hemoglobinopathies are hereditary disorders of the hemoglobin molecule with a high prevalence worldwide. Brazil has a prevalence of 0.1 to 0.3% of newborns with sickle cell anemia and 20.0 to 25.0% of heterozygous alpha2 thalassemia among African Brazilians. In the present study, we investigated the presence of variant hemoglobins and alpha2(3.7 Kb) and alpha2 (4.2 Kb) thalassemia in newborns from Salvador, Bahia, Brazil. Samples of umbilical cord blood from a total of 590 newborns were analyzed, of which 57 (9.8%) were FAS; 36 (6.5%) FAC; one (0.2%) SF; and five (0.9%) FSC. One hundred fourteen (22.2%) newborns had alpha2(3.7 Kb) thalassemia, of whom 101 (19.7%) were heterozygous and 13 (2.5%) homozygous, showing statistical significance for hematological data between newborns with normal alpha genes and alpha2(3.7 Kb) thalassemia carriers. The alpha2(4.2 Kb) thalassemia was not found. Frequencies found in the present study confirm that hemoglobinopathies are a public health problem in Brazil, emphasizing the need for neonatal screening and genetic counseling programs.

Anemia, Sickle Cell↗

PubMed2000

Absence of platelet CD40L identifies patients with X-linked hyper IgM syndrome.

CD40 ligand (CD40L), a membrane protein expressed on activated T cells, plays a pivotal role in B cell proliferation and differentiation. Mutations in the CD40L gene are associated with a rare immunodeficiency state, X-linked hyper IgM syndrome (XLHIGM). Recently, platelets have been described as capable of expressing CD40L within minutes of stimulation. We have developed a rapid technique to determine expression of CD40L on activated platelets by flow cytometry in whole blood. We have demonstrated that this technique is useful in neonatal screening, in rapid diagnosis and in determining reconstitution by donor bone marrow post-transplantation.

Animals↗

PubMed2000

Technical report: congenital adrenal hyperplasia. Section on Endocrinology and Committee on Genetics.

The Section on Endocrinology and the Committee on Genetics of the American Academy of Pediatrics, in collaboration with experts from the fields of pediatric endocrinology and genetics, developed this policy statement as a means of providing up-to-date information for the practicing pediatrician about current practice and controversial issues in congenital adrenal hyperplasia (CAH), including the current status of prenatal diagnosis and treatment, the benefits and problem areas of neonatal screening programs, and the management of children with nonclassic CAH. The reference list is designed to allow physicians who wish more information to research the topic more thoroughly.

Adrenal Hyperplasia, Congenital↗

PubMed2003

Disparity between pediatricians' knowledge and practices regarding perinatal human immunodeficiency virus counseling and testing.

OBJECTIVES: This survey of members of the American Academy of Pediatrics (AAP) was initiated by the AAP Committee on Pediatric AIDS to assess the knowledge, attitudes, and behaviors of pediatricians regarding prenatal and neonatal screening as a means to reduce mother-to-child transmission of human immunodeficiency virus (HIV). METHODS: The survey consisted of a 4-page, self-administered questionnaire, which was mailed to a random sample of 1647 active US members of the AAP. The original and 5 subsequent mailings to nonresponders were conducted from July to November 2001. RESULTS: Completed questionnaires were received from 982 pediatricians, for a response rate of 59.6%. Nearly all pediatricians (96.6%) agree on the importance of knowing the HIV status of pregnant women, and more than three-fourths (78.5%) do not think that HIV screening during pregnancy or postpartum should be limited to women with perceived risk for infection. Approximately 6 (58.5%) of 10 pediatricians indicate that they counsel or provide education on HIV screening to pregnant women or mothers of newborns whose HIV status is unknown; 41.5% do not. Pediatricians reported evaluating an average of 56 newborns each during the 3 months before the survey. The HIV infection status of the mother was unknown for 40.6% of these cases. During the same time period, pediatricians said that they discussed a newborn or maternal HIV screening test with only 10.4% of the mothers whose HIV infection status was unknown. Reasons given for not counseling mothers with unknown HIV infection status about maternal and/or newborn screening for HIV included low prevalence of HIV in the pediatrician's practice area (65.4%), assessment by the pediatrician that the parents did not fit the profile of those "at risk" for HIV infection (56.1%), fear of offending the parents (50.2%), parental lack of understanding regarding the importance of screening (50.1%), and lack of sufficient time for counseling (44.4%). CONCLUSIONS: Pediatricians exhibit a high degree of understanding of the importance of HIV screening as a means to reduce mother-to-child transmission of HIV, but this does not always translate into their clinical practices.

Adult↗

PubMed2003

[Neonatal detection of sickle cell disease].

An experimental program for neonatal detection of sickle cell disease (SCD) was performed in France in 1990. Our data indicated a high prevalence of SCD, one patient in 1,250 newborns tested. The French national program for neonatal screening for SCD was set up in 1995 by the Association Française pour le Dépistage et la Prévention des Handicaps de l'Enfant (AFDPHE). This is not a systematic program, but only targeted at newborns at risk for SCD.

Anemia, Sickle Cell↗

PubMed2006

[Screening of hemoglobinopathies in a cohort of newborns in Madrid].

BACKGROUND AND OBJECTIVE: Congenital structural hemoglobinopathies are a group of disorders whose incidence has experienced an increase in recent years, due to the higher number of immigrants living in the Region of Madrid. Given the possibility of starting early prophylactic measures, it seems advisable to carry out an screening of hemoglobinopathies in this region. The objective of this work was to know the current incidence of hemoglobinopathies in the Hospital Clinico San Carlos and to analyze the more suitable laboratory diagnostic tests. SUBJECTS AND METHOD: An ambispective cohort study, with 3,365 newborns studied at the Hospital Clinico San Carlos from May 2003 to June 2004. All were studied by cation exchange HPLC [Variant (Bio-Rad)] and pathologic specimens were analyzed by reversed phase HPLC. RESULTS: Hemoglobinophaty was detected in 26 children with the HPLC Variant, with a global incidence of 7.7 per 1,000 newborns: 1 case of sickle cell disease, 18 cases of sickle cell trait, 1 HbC, 1 HbE/A2 and five indeterminate cases. CONCLUSIONS: Neonatal screening for hemoglobinopathies in the Region of Madrid is necessary, and the HPLC Variant is an appropriate technique.

Cohort Studies↗

PubMed1992

[Total cholesterol, LDL-cholesterol and apoprotein B in umbilical cord blood: cross-sectional study].

The aim of the present study was to evaluate, in a large series of term newborns, the prevalence of hypercholesterolemia in cord blood, using as parameters, levels of plasma cholesterol, LDL-cholesterol and apo B higher than mean + 2 standard deviations, alone or in association. Data reported here represent the results of a transversal study. 1275 term newborns were studied. In everybody, in cord blood samples, at birth, cholesterol, triglycerides, HDL-cholesterol, apoprotein B and LDL-cholesterol have been assayed. In 3.13% of them (40 subjects), cholesterol levels > mean + 2 standard deviations were present. Moreover, only 6 subjects (0.47%) showed all three parameter levels higher than mean + 2 standard deviations, and 4 subjects (0.31%), in spite of normal cholesterol levels, presented high LDL-cholesterol and apo B levels. Integrated utilization of these parameters in the neonatal screening of familial hypercholesterolemia will have to be confirmed by follow-up studies.

Apolipoproteins B↗

PubMed2003

Characteristic acylcarnitine profiles in inherited defects of peroxisome biogenesis: a novel tool for screening diagnosis using tandem mass spectrometry.

Patients with inherited defects of peroxisomal metabolism, a class of diseases with marked clinical and genetic heterogeneity, show a characteristic phenotype in most cases with severe neurologic impairment, craniofacial abnormalities, and hepatic and kidney dysfunction. For the differential diagnosis of clinically suspected cases, a complex biochemical and genetic approach is required. Analysis of plasma very-long-chain fatty acids is a reliable screening method to detect most but not all peroxisomal disorders. To study the potential presence of abnormal acylcarnitine species in plasma and blood, we screened by tandem mass spectrometry a series of patients affected by a peroxisome biogenesis disorder (PBD) and compared the results with those obtained in patients with isolated peroxisomal defects (e.g. D-bifunctional protein deficiency, X-linked adrenoleukodystrophy) and mitochondrial long-chain fatty acid oxidation defects. The most relevant finding observed in plasma of patients with PBD was a significant increase of long-chain dicarboxylic C16- and C18-carnitine, i.e. hexadecanedioyl- and octadecanedioyl-carnitine, with high dicarboxylycarnitine/monocarboxylylcarnitine ratio. Elevation of very long-chain acylcarnitines C24- and C26-, i.e. lignoceroyl- and cerotoyl-carnitine, was detected in some PBDs and in D-bifunctional protein deficiency. Similar abnormalities were also found in neonatal screening blood spots. Detection of these compounds alone, in the absence of other shorter-chain acylcarnitines, is highly specific and characteristic of PBD, as confirmed by the differing profiles observed in patients with adrenoleukodystrophy and mitochondrial long-chain fatty acid oxidation defects. Our study adds a novel method to the diagnosis of PBD, which may also be of benefit for future neonatal mass screening programs based on acylcarnitine profiling.

Carnitine↗

PubMed2006

Newborn screening for hepatorenal tyrosinemia: Tandem mass spectrometric quantification of succinylacetone.

BACKGROUND: False-positive and false-negative results occur in current newborn-screening programs for hepatorenal tyrosinemia, which measure tyrosine concentrations in blood spots, sometimes in combination with other metabolites, including succinylacetone. We present our experience with a newly described method for succinylacetone quantification in routine newborn screening. METHODS: Succinylacetone was extracted from blood spots that had already been extracted with absolute methanol for acylcarnitine and amino acid analysis. The solvent was acetonitrile-water (80:20 by volume) containing formic acid, hydrazine hydrate, and 100 nmol/L 5,7-dioxooctanoic acid as internal standard. Analysis was performed by tandem mass spectrometry in a separate run. RESULTS: Of 61,344 samples, 99.6% had succinylacetone concentrations < or =5 micromol/L. With a cutoff of 10 micromol/L, no false-positive results were obtained. In 2 patients, the succinylacetone concentrations in the dried blood spots from the 36th and 56th hours of life were 152 and 271 micromol/L, respectively, and the tyrosine concentrations were 54 and 129 micromol/L. Hepatorenal tyrosinemia was subsequently confirmed in both patients. Retrospective analysis of the neonatal screening samples of 2 additional known patients revealed increased succinylacetone concentrations of 46 and 169 micromol/L, respectively. CONCLUSIONS: Tandem mass spectrometric quantification directly from residual blood spots is a useful method for the early detection of hepatorenal tyrosinemia in newborn-screening programs.

Blood Specimen Collection↗

PubMed2001

[Neonatal hearing loss screening using otoacoustic emission with Echocheck].

OBJECTIVES: Few studies have been published on neonatal hearing loss screening using the Echocheck system (a new and easy method for detecting otoacoustic emissions). The aim of this study was to demonstrate how, in combination with auditory evoked potentials, this system can be used with satisfactory results for universal screening of all live births. METHODS: Otoacoustic emissions in the 1,000 infants born in our hospital during a 10-months period were checked by Echocheck. According to a preestablished protocol, neonates who failed the first screening test were sent for diagnosis by auditory brainstem responses. RESULTS: Coverage of the test was 99.3%. In 25% of the patients the test was repeated. Deafness was found in eight infants (only in two infants at high risk). The results obtained with this new method were compared with published results for the ILO systems. CONCLUSIONS: Echocheck provides more data than the standard recommended for neonatal hearing loss screening which, together with the results obtained in previous studies, suggests that Echocheck can be used like other systems for neonatal screening programmes. Since it is easy to use and cheaper than screening programmes, this system facilitates universal screening.

Deafness↗

PubMed2002

Negative sweat test in hypertrypsinaemic infants with cystic fibrosis carrying rare CFTR mutations.

UNLABELLED: Persistent hypertrypsinaemia in newborn screening for cystic fibrosis (CF) recognises subjects at high risk to be affected. Diagnosis is confirmed by a positive sweat test and/or by the presence of two mutations in the cystic fibrosis transmembrane regulator gene. The aim of the present study was to evaluate the occurrence of a negative sweat test (chloride < 60 mmol/l) during the first months of life, in hypertrypsinaemic infants, which would lead to a delayed diagnosis. We reviewed clinical charts of CF patients born between January 1993 and September 1998, when the neonatal screening programme consisted of an immunoreactive trypsinogen (IRT)/DNA (F508del) + IRT strategy. Laboratory and clinical data were collected for patients diagnosed after 12 months of life. Out of 446,492 newborns, 104 CF patients were diagnosed giving an overall incidence of 1:4293. Of these, six had a blood IRT level above the cut off value (99th percentile) and a negative sweat test in the first trimester of life. At a mean age of 3.5years, the patients were again referred to our CF Centre for re-evaluation in order to confirm or exclude the disorder. Molecular analysis identified the following genotypes: F508del/A309D, F508del/3849 + 10kbC-->T, F508del/R117H (in two patients), R117H/ L997F, and F508del/R117L. CONCLUSION: Infants with cystic fibrosis bearing a spectrum of mild cystic fibrosis transmembrane regulator gene mutations may present as hypertrypsinaemic newborns with a sweat chloride within the normal range. Reference values for normal sweat test during the first months of life should be revised. A wide molecular genetic analysis is recommended for newborns presenting persistent hypertrypsinaemia and a sweat test result > 30 mmol/l in order to diagnose atypical forms of the disease.

Child↗

PubMed2002

Gas chromatography-mass spectrometry method for determination of phenylalanine and tyrosine in neonatal blood spots.

In this paper we developed a simple, rapid and sensitive method for the quantitative analysis of phenylalanine (Phe) and tyrosine (Tyr) in dried blood spots of newborns by gas chromatography-mass spectrometry (GC-MS). Phe and Tyr in blood samples were reacted with N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide at 120 degrees C for 30 min and their corresponding single derivatives were obtained. Phe and Tyr were determined by measurement of their derivatives by GC-MS in the selected ion monitoring mode. Contents of Phe and Tyr in blood spots were calculated by external standard method. The ratio of Phe to Tyr was used for neonatal screening for phenylketonuria. The present method only took a few minutes to perform and required minimal sample preparation. In addition it provided low detection limits of 1.2 micromol l(-1) for Phe and 1.6 micromol l(-1)for Tyr.

Gas Chromatography-Mass Spectrometry↗

PubMed1999

Health visitor screening versus vigilance: outcomes of programmes for detecting permanent childhood hearing loss in west Berkshire.

The Health Visitor Distraction Test (HVDT) screen for hearing was replaced in West Berkshire in 1989 with a vigilance programme incorporating a questionnaire. The detection of permanent congenital deafness (bilateral > 50 dB HL) for all children born since 1984 has been audited to compare the two regimes. Sixty-two cases met the criteria, giving an ascertainment of 1.0 per 1000. Performance was similar under the two systems for severe/profound losses (> 70 dB HL), but there was a longer tail of late-detected moderate losses (50-70 dB HL) under the vigilance regime. The sensitivity of the Health Visitor questionnaire in referring those with permanent hearing loss was very similar to that of the HVDT (39% compared with 42%). Coverage for the questionnaire was approximately 87%, but only 78% for the known cases. Referral rate was lower under the vigilance programme, at approximately 3%. The results suggest that a vigilance programme is likely to perform as well as the HVDT but no better. Despite subsequent modifications to the vigilance programme, the poor pickup of moderate losses probably indicates the limitations of parental and professional observation in detecting partial hearing problems. The evidence adds support to the recent recommendations for universal neonatal screening.

Age Distribution↗

PubMed2005

Maternal views on infant hearing loss in a developing country.

BACKGROUND: Parental support for infant hearing loss is essential for a successful infant screening programme. However, in developing countries where unfavourable customs and beliefs towards childhood disabilities have been reported, parental support towards infant screening is uncertain and there is presently no published evidence on the subject. OBJECTIVE: To elicit the views of mothers and would-be mothers in order to ascertain their knowledge on infant hearing loss and their attitudes towards infant hearing screening. METHODS: A structured questionnaire consisting of 15 questions was administered to 101 mothers (mean age 31.6+/-7.3 years, range: 21-55 years) attending two community hospitals in Lagos, Nigeria. The responses were evaluated by descriptive statistics, factor analysis of the principal components and multiple regression analysis. The reliability of the two main domains (knowledge and attitude) was tested for internal consistency by Cronbach's alpha coefficient. RESULTS: Maternal knowledge was highest for measles (73%; mean score 2.54) and ear discharge (73%; mean score 2.51) but low for birth asphyxia (37%; mean score 1.90), traditional medicine (42%; mean score 2.03) and jaundice (47%; mean score 2.09) as causes of hearing loss. Attitude towards neonatal screening was positive in majority of mothers (92%; mean score 2.84) and there was a high acceptance of hearing aids as an early intervention option (84%; mean score 2.70). Five factors (eigenvalue>1) were extracted after principal component analysis with the attitude variables loading highly and exclusively on one factor. Age was the only demographic variable that was associated with a domain (knowledge) after multiple regression analysis. The component scales for the two domains were highly internally consistent (alpha coefficients of 0.84 and 0.83). CONCLUSIONS: Contrary to the concerns often expressed about parental support for infant hearing screening programmes in developing countries, this study suggests that current parental knowledge and attitude favour early detection and intervention of childhood hearing impairment.

Adult↗

PubMed2001

Hepatic carnitine palmitoyl transferase 1 (CPT1 A) deficiency in North American Hutterites (Canadian and American): evidence for a founder effect and results of a pilot study on a DNA-based newborn screening program.

We describe six patients with hepatic carnitine palmitoyl transferase (CPT1 A) deficiency who are members of a large extended Hutterite kindred living in widely scattered communities in the United States and Canadian Prairies. Two patients have significant neurological impairment due to severe recurrent hypoglycemic crises. The remaining four patients with earlier detection and treatment have near normal outcomes. The Canadian and American Hutterite families share two common ancestors who married in 1812, about 60 years before the Hutterites arrived in North America and prior to their subdivision into the three groups (Schmiedeleut, Dariusleut, and the Lehrerleut). These patients share a common haplotype on chromosome 11q13 and are all homozygous for a common CPT1 A G710E mutation, suggesting a founder effect. The clustering of such a rare disorder of fatty acid oxidation prompted us to initiate a pilot DNA-based neonatal screening program to determine the carrier frequency of this mutation in Hutterite newborns with the participation and support of the community. To date our carrier frequency is 1/16, close to the predicted frequency based on diagnosed patients and number of births. We believe our newborn screening program for CPT1 A deficiency in the Hutterite community will serve as a prototype model for delivery of targeted genetic services to other similar unique genetic isolates.

Adolescent↗