References of "SCHOOS, Roland"
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See detailSurprising causes of C5-carnitine false positive results in newborn screening.
BOEMER, François ULg; SCHOOS, Roland ULg; de HALLEUX, Virginie ULg et al

in Molecular genetics and metabolism (2014), 111(1), 52-4

During an 18-month period, we noticed an alarming increase of newborn screening false positivity rate in identifying isovaleric acidemia. In 50 of 50 newborns presenting elevated C5-carnitine, we ... [more ▼]

During an 18-month period, we noticed an alarming increase of newborn screening false positivity rate in identifying isovaleric acidemia. In 50 of 50 newborns presenting elevated C5-carnitine, we confirmed the presence of pivaloylcarnitine. Exogenous pivalate administration had been previously identified as the causal agent of this concern. No pivalic-ester prodrug is commercially available in Belgium, but pivalic derivates are also used in the cosmetic industry as emollient under the term "neopentanoate". We have identified neopentanoate-esters in a nipple-fissure unguent that was provided to young mothers. Ceasing distribution of this product hugely reduced the C5-carnitine false positivity rate. [less ▲]

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See detailHETEROGENOUS CLINICAL AND LABORATORY PRESENTATIONS IN MAD DEFICIENCY
BOEMER, François ULg; SCHOOS, Roland ULg; ACQUAVIVA, Cécile et al

Poster (2013, September)

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See detailEnhanced interpretation of newborn screening results without analyte cutoff values
Marquardt, G.; Currier, R.; McHugh, D. M. S. et al

in Genetics in Medicine (2012), 14(7), 648-655

Purpose: To improve quality of newborn screening by tandem mass spectrometry with a novel approach made possible by the collaboration of 154 laboratories in 49 countries. Methods: A database of 767,464 ... [more ▼]

Purpose: To improve quality of newborn screening by tandem mass spectrometry with a novel approach made possible by the collaboration of 154 laboratories in 49 countries. Methods: A database of 767,464 results from 12,721 cases affected with 60 conditions was used to build multivariate pattern recognition software that generates tools integrating multiple clinically significant results into a single score. This score is determined by the overlap between normal and disease ranges, penetration within the disease range, differences between conditions, and weighted correction factors. Results: Ninety tools target either a single condition or the differential diagnosis between multiple conditions. Scores are expressed as the percentile rank among all cases with the same condition and are compared to interpretation guidelines. Retrospective evaluation of past cases suggests that these tools could have avoided at least half of 279 false-positive outcomes caused by carrier status for fatty-acid oxidation disorders and could have prevented 88% of known false-negative events. Conclusion: Application of this computational approach to raw data is independent from single analyte cutoff values. In Minnesota, the tools have been a major contributing factor to the sustained achievement of a false-positive rate below 0.1% and a positive predictive value above 60%. © 2012 American College of Medical Genetics and Genomics. [less ▲]

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See detailNeonatal thyroid-stimulating hormone concentrations in Belgium: a useful indicator for detecting mild iodine deficiency?
Vandevijvere, S; Coucke, W; Vanderpas, J et al

in PLoS ONE (2012)

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See detail3-years experience review of neonatal screening for hemoglobin disorders using tandem mass spectrometry.
BOEMER, François ULg; Cornet, Yves ULg; LIBIOULLE, Cécile ULg et al

in Clinica Chimica Acta (2011), 412(15-16), 1476-9

BACKGROUND: Neonatal screening programs for sickle cell disease are common in North America and in some European countries. Isoelectric Focusing or High Performance Liquid Chromatography is the main ... [more ▼]

BACKGROUND: Neonatal screening programs for sickle cell disease are common in North America and in some European countries. Isoelectric Focusing or High Performance Liquid Chromatography is the main technique used for hemoglobin variant detection. METHODS: Since tandem mass spectrometry is being used for screening of inherited metabolic disorders and allows protein identification, we had developed an application to identify the most relevant hemoglobin mutations with this technology. RESULTS: This approach had been previously validated and has been routinely applied in our laboratory for the last three years. We report here our experience with this new method in the field, applied to our East-Belgian population. CONCLUSIONS: To conclude, mass spectrometry provides an efficient alternative approach for laboratories performing neonatal screening of hemoglobin disorders. [less ▲]

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See detailAnalytical validation based on total error measurement and cut-off interpretation of a neonatal screening TSH-immunoassay.
Boemer, François ULg; Bours, Vincent ULg; Schoos, Roland ULg et al

in Journal of Chromatography. B : Analytical Technologies in the Biomedical & Life Sciences (2009), 877

To prevent the severe developmental and physical morbidities associated with congenital hypothyroidism, we developed a home-made Enzyme-Linked Immunosorbent Assay (ELISA) method to quantify Thyroid ... [more ▼]

To prevent the severe developmental and physical morbidities associated with congenital hypothyroidism, we developed a home-made Enzyme-Linked Immunosorbent Assay (ELISA) method to quantify Thyroid Stimulating Hormone (TSH) levels on newborn dried blood spots. In order to agree with actual clinical laboratory quality referential (ISO 15189), we desired to update our analytical validation protocol. For this purpose, an approach using accuracy profiles based on tolerance intervals for the total error measurement was for first time applied to an immunological assay. According to acceptance limits fixed at +/-30%, the method was found accurate over a concentration range from 17.48 to 250mIU/L. Based on 99.5 percentile of a 16,459 newborn population, cut-off was fixed at 20.1mIU/L and validated against normal and pathologic neonatal populations. Additionally, uncertainty regions around this value were obtained applying four different approaches. Finally, we demonstrated here our in-house immunological technique fulfils criterions of a neonatal screening policy. [less ▲]

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See detailNewborn Screening for Sickle Cell Disease Using Tandem Mass Spectrometry
Boemer, François ULg; Ketelslegers, Olivier; Minon, Jean-Marc et al

in Clinical Chemistry (2008), 54(12), 2036-2041

BACKGROUND: Neonatal screening programs for sickle cell disease are now widespread in North American and European countries. Most programs apply isoelectric focusing or HPLC to detect hemoglobin variants ... [more ▼]

BACKGROUND: Neonatal screening programs for sickle cell disease are now widespread in North American and European countries. Most programs apply isoelectric focusing or HPLC to detect hemoglobin variants. Because tandem mass spectrometry (MS/MS) is being used for screening of inherited metabolic disorders and allows protein identification, it was worth testing for hemoglobinopathy screening. METHODS: We minimized sample preparation and analysis times by avoiding prior purification, derivatization, or separation. We developed a tryptic digestion methodology to screen for the main clinically important variants (HbS, HbC, and HbE) and beta-thalassemia. To ensure proper discrimination between homozygote and heterozygote variants, we selected 4 transitions with good signal intensities for each specific peptide and calculated variant/HbA ratios for each. Method validation included intra- and interseries variability, carryover, and limit of detection. We also performed a comparative study with isoelectric focusing results on 2082 specimens. RESULTS: Intraassay imprecision values (CVs) varied between 2.5% and 30.7%. Interassay CVs were between 6.3% and 23.6%. Carryover was <0.03%, and the limit of detection was fixed at 1% of HbS. According to the MS/MS settings (detection of HbS, HbC, HbE, and beta-globin production defects), the comparative study did not yield any discrepant results between the 2 techniques. CONCLUSIONS: MS/MS is a reliable method for hemoglobinopathy neonatal screening. [less ▲]

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See detailMolecular Analysis in Two Siblings African Patients with Severe Form of Hunter Syndrome: Identification of a Novel (P.Y54x) Nonsense Mutation
Mutesa, Léon; Muganga, N.; Lissens, Willy et al

in Journal of Tropical Pediatrics (2007), 53(6), 434-7

Hunter syndrome (or Mucopolysaccharidosis type II, MPS II) is an X-linked recessive disorder due to the deficiency of the iduronate-2-sulfatase (IDS) enzyme, resulting in the accumulation of heparan and ... [more ▼]

Hunter syndrome (or Mucopolysaccharidosis type II, MPS II) is an X-linked recessive disorder due to the deficiency of the iduronate-2-sulfatase (IDS) enzyme, resulting in the accumulation of heparan and dermatan sulfates in the lysosomes. The heterogeneity of clinical phenotypes, ranging from mild-to-severe forms, is a result of different mutations in the IDS gene. We report here, a novel nonsense mutation (p.Y54X) in two siblings MPS II African patients affected with a severe form of the disease. We postulated that the p.Y54X mutation which causes a loss of the IDS region highly conserved among sulfatase enzymes, could be predicted as a severe disease-causing mutation for Hunter syndrome. [less ▲]

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See detailNeonatal screening for sickle cell disease in Central Africa: a study of 1825 newborns with a new enzyme-linked immunosorbent assay test
Mutesa, Léon; Boemer, François ULg; Ngendahayo, Louis et al

in Journal of Medical Screening (2007), 14(3), 113-116

Objectives To evaluate the feasibility of systematic neonatal screening for sickle cell disease in the region of Great Lakes in Central Africa using a new approach with limited costs. Methods Between July ... [more ▼]

Objectives To evaluate the feasibility of systematic neonatal screening for sickle cell disease in the region of Great Lakes in Central Africa using a new approach with limited costs. Methods Between July 2004 and July 2006, 1825 newborn dried blood samples were collected onto filter papers in four maternity units from Burundi, Rwanda and the East of the Democratic Republic of Congo. We tested for the presence of haemoglobin C and S in the eluted blood by an enzyme-linked immunosorbent assay (ELISA) test using a monoclonal antibody. All ELISA-positive samples (multiple of the median (MoM) >= 1.5) were confirmed by a simple molecular test. The statistica software version 7.1 was used to create graphics and to fix the MoM cut-off, and the chi(2) of Pearson was used to compare the genotype incidences between countries. Results Of the 1825 samples screened, 97 (5.32%) were positive. Of these, 60 (3.28%) samples were heterozygous for Hb S, and four (0.22%) for Hb C; two (0.11%) newborns were Hb SS homozygotes. Conclusions The lower cost and the high specificity of ELISA test are appropriate for developing countries, and such systematic screening for sickle cell anaemia is therefore feasible. [less ▲]

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See detailScreening for sickle cell disease on dried blood: a new approach evaluated on 27,000 Belgian newborns
Boemer, François ULg; Vanbellinghen, Jean-François ULg; Bours, Vincent ULg et al

in Journal of Medical Screening (2006), 13(3), 132-136

Setting Early diagnosis of sickle cell disease decreases morbidity. However, cost-effective screening programmes are not yet available. Methods We explored the feasibility of systematic screening ... [more ▼]

Setting Early diagnosis of sickle cell disease decreases morbidity. However, cost-effective screening programmes are not yet available. Methods We explored the feasibility of systematic screening performed on dried blood harvested from five-day-old newborns. Results A total of 27,010 samples were collected in Belgian maternity units between June 2003 and February 2005, and the presence of haemoglobin (Hb) C or S in the eluted blood was examined by an enzyme-linked immunosorbent assay (ELISA) test performed with a monoclonal antibody detecting both mutated forms. As this antibody slightly cross-reacts with Hb A, better specificity is achieved if the test is performed not later than day 5. Among the 27,010 samples, 132 (0.49%) were positive. Molecular biology tests performed on dried blood from positive samples showed that 106 of these babies were heterozygotes for the Hb S mutation and three were heterozygotes for the Hb C mutation, while three newborns were SS homozygotes (0.011%). Seventeen samples (0.063%) were false-positives as we could not detect any mutation. Conclusions We have developed a new immunological approach in the field of haemoglobinopathy neonatal screening. This ELISA test is cheap (E0.2 /test or E1800/cletected SS homozygote) and could be centralized. Its cost-effectiveness in the whole Belgian population is comparable with that of screening for phenylketonuria or congenital adrenal hyperplasia. Further improvements should obviously be achieved in order to better discriminate heterozygotes and homozygotes, but the accessibility and the low cost of the test are relevant arguments for the screening extension in a wide range of countries, especially in Central Africa. [less ▲]

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See detailMajor Decrease in the Incidence of Trisomy 21 at Birth in South Belgium: Mass Impact of Triple Test?
Verloes, Alain ULg; Gillerot, Y.; Van Maldergem, Lionel ULg et al

in European Journal of Human Genetics (2001), 9(1), 1-4

In South Belgium (Wallonia), the 'triple test' was introduced in 1990-1991, and is nowadays a widely accepted screening method for assessment of trisomy 21 risk in pregnancy. The 'triple test' is not ... [more ▼]

In South Belgium (Wallonia), the 'triple test' was introduced in 1990-1991, and is nowadays a widely accepted screening method for assessment of trisomy 21 risk in pregnancy. The 'triple test' is not regulated and can be freely performed by any biomedical lab, making epidemiological data unavailable. By contrast, cytogenetic investigations are limited to a few genetic centres, and accurate statistics can be easily built from their files. During the period 1984-1989, a total of 244 trisomy 21 (1/876 pregnancies) were diagnosed in the Genetic Centres of Liege and Loverval, 42 (17%) of them prenatally. During the period 1993-1998, 294 trisomy 21 (1/704 pregnancies) were observed, 165 (56%) of which prenatally, and more than 90% of affected pregnancies were terminated. Even after correction for late foetal loss of trisomic foetuses, the difference is highly significant, and corresponds to a theoretical shift in the incidence of trisomy 21 at birth from 1/794 to 1/1606. As no remarkable progress occurred in other non-invasive prenatal screening procedures or general health care policies in Belgium, the most reasonable explanation is the use on a large scale of triple test by pregnant women, and the election of termination for most affected pregnancies. [less ▲]

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See detailA Prenatal Trisomy 21 Screening Program Using Alpha-Fetoprotein, Human Chorionic Gonadotropin, and Free Estriol Assays on Maternal Dried Blood
Verloes, Alain ULg; Schoos, Roland ULg; Herens, Christian ULg et al

in American Journal of Obstetrics and Gynecology (1995), 172(1, Pt 1), 167-74

OBJECTIVE: The feasibility of large-scale Down syndrome maternal screening with dried blood samples and nonradioactive methods was examined. STUDY DESIGN: A prospective observation study was performed on ... [more ▼]

OBJECTIVE: The feasibility of large-scale Down syndrome maternal screening with dried blood samples and nonradioactive methods was examined. STUDY DESIGN: A prospective observation study was performed on a nonselected population of 11,241 pregnant women sampled between January 1991 and September 1992, between 14 and 24 weeks' gestation (ultrasonographic scanning available for 91.6%), through a multicenter collaborative network. Enzyme-linked immunosorbent assays for alpha-fetoprotein, human chorionic gonadotropin, and free estriol were performed on dried blood samples. Risk determination was made with an in-house software implementing the multivariate gaussian log likelihood method. RESULTS: A total of 10,450 samples were eligible for the study. Mean age at term was 27.9 years. A total of 6.84% of the patients were > or = 35 years old with a prior risk of trisomy 21 > 1:350. The general positive rate of our sample was 8.15%. After calculation 31.7% with prior risk > 1:350 were still in the high-risk group; 6.36% of the low-risk group were found to be at high risk for Down syndrome. Fifteen trisomic pregnancies were observed, of which 11 had a calculated risk higher than the selected cutoff value (1:350). The overall detection rate was 73%, specificity was 92%, and positive predictive power was 1.2%. CONCLUSION: Our pilot study has shown performances within the range of conventional serum screening programs. Dried blood assays are a handy alternative to serum assays. Blot paper cards represent a simple method of sampling, well fitted for large population screening. Combined with nonradioactive methods, this method appears to be both low cost and effective. The current work apparently is the first large-scale Down screening program performed with dried blood. [less ▲]

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See detailLe dépistage prénatal de la trisomie 21 sur sérum maternel. Mise au point
Koulischer, Lucien ULg; Schoos, Roland ULg; Verloes, Alain ULg et al

in Revue Médicale de Liège (1991), 46(12), 625-32

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