Danish Neonatal Screening Biobank Research Articles

Extreme neonatal hyperbilirubinemia and a specific genotype: a population-based case-control study.

Extreme hyperbilirubinemia (plasma bilirubin ≥ 24.5 mg/dL) is an important risk factor for severe bilirubin encephalopathy. Several risk factors for hyperbilirubinemia are known, but in a large number of patients, a causal factor is never established. UGT1A1 is the rate-limiting enzyme in bilirubin's metabolism. The genotype of Gilbert syndrome, the UGT1A1*28 allele, causes markedly reduced activity of this enzyme, but its association with neonatal hyperbilirubinemia is uncertain and its relationship with extreme hyperbilirubinemia has not been studied. We examined whether the UGT1A1*28 allele is associated with extreme hyperbilirubinemia. The UGT1A1*28 allele was assessed in a case-control study of 231 white infants who had extreme hyperbilirubinemia in Denmark from 2000 to 2007 and 432 white controls. Cases were identified in the Danish Extreme Hyperbilirubinemia Database that covers the entire population. Genotypes were obtained through the Danish Neonatal Screening Biobank. Subgroup analysis was done for AB0 incompatible cases. No association was found between the UGT1A1*28 allele and extreme hyperbilirubinemia. With the common genotype as reference, the odds ratio of extreme hyperbilirubinemia was 0.87 (range, 0.68-1.13) for UGT1A1*28 heterozygotes and 0.77 (range, 0.46-1.27) for homozygotes. Also, no association was found for AB0 incompatible cases. The UGT1A1*28 allele was not associated with risk for extreme hyperbilirubinemia in this study.

UGT1A1*28 polymorphism and acute lymphoblastic leukemia in children: a Danish case-control study.

Oxidative stress is a possible risk factor in the development of acute lymphoblastic leukemia (ALL) in children. Bilirubin is a potent endogenous antioxidant, and the UGT1A1*28 polymorphism is the main genetic cause of variation in plasma bilirubin in Western Europe. In a case-control study of 665 incident cases of ALL in childhood in Denmark 1982-2010 and 1,379 controls, associations between UGT1A1*28 genotypes and ALL in childhood were estimated as odds ratios by logistic regression with adjustment for sex and birth decade. Subgroup analyses were carried out by age at onset in three groups, and on the ALL subtypes precursor B-cell, T-cell, and t(12;21) positive status. Cases were identified in The Danish Registry of Childhood Cancer, and genotypes were estimated from dried blood spots stored in The Danish Neonatal Screening Biobank. Controls were newborns with blood spots taken right before and after a case. We found no association between ALL in childhood and UGT1A1*28 genotypes. The odds ratio was 1.01 (0.88-1.17) for heterozygotes and 1.03 (0.78-1.36) for homozygotes. Also, no associations were found in the subgroup analyses. We found no association between the UGT1A1*28 genotypes and ALL in children.

Neonatal Levels of Inflammatory Markers and Later Risk of Schizophrenia

BackgroundThere is a long-standing interest in investigating the impact of early-life immune abnormalities on later onset of psychosis. The aim of this study was to assess inflammatory marker levels in neonatal dried blood spots and their association with later risk of schizophrenia. MethodsThis nested case-control study included 995 cases and 980 control subjects. Cases were identified using the Danish Psychiatric Central Register. Control subjects of same age and sex were identified using the Danish Civil Registration System. Samples for the identified individuals were retrieved from the Danish Neonatal Screening Biobank. Concentrations of 17 inflammatory markers were measured in eluates from dried blood spots using a bead-based multiplex assay. Incidence rate ratios were calculated using conditional logistic regression. Principal component analysis was used to capture the overall variation in the inflammatory markers’ concentrations. ResultsNo significant differences were found for any of the analyzed interleukins. We did not find any association with schizophrenia for any of the other examined inflammatory markers. ConclusionsOur results suggest that persons who develop schizophrenia do not have higher or lower levels of the examined inflammatory markers at the time of birth. Our findings differ from the studies of maternal inflammatory changes during the antenatal period for which associations with schizophrenia have previously been demonstrated.

Mannose-binding lectin gene, MBL2, polymorphisms are not associated with susceptibility to invasive pneumococcal disease in children.

Most children are transiently colonized with Streptococcus pneumoniae, but very few develop invasive pneumococcal disease (IPD). Host genetic variation of innate immunity may predispose to IPD. We investigated the effect of genetic variation in the mannose-binding lectin gene, MBL2, on susceptibility and disease severity of IPD in previously healthy children aged <5 years. IPD cases were identified through national registries. DNA was obtained from the Danish Neonatal Screening Biobank. Pneumococcal serotypes were determined by Quellung reaction. The associations between MBL2 diplotypes and IPD susceptibility, serotypes, and outcome were investigated using logistic regression analysis. We included 372 cases with meningitis, 907 with bacteremia, and 1263 age- and sex-matched controls; 2372 individuals were successfully genotyped and assigned MBL2 diplotypes. The median age in our combined case series was 13 months. Children with defective diplotypes were not at higher risk for meningitis than children with other diplotypes (odds ratio [OR], 0.85; 95% confidence interval [CI], .56-1.28). Similar results were found for bacteremia (OR, 0.89; 95% CI, .68-1.15) as well as for all cases (OR, 0.87; 95% CI, .70-1.09). There was no association with susceptibility to recurrent IPD (n = 12) for children with defective diplotypes compared with cases with a single episode (OR, 0.53; 95% CI, .07-4.13) and with all controls (OR, 0.46; 95% CI, .06-3.56). There was no association between diplotypes and mortality or between diplotypes and pneumococcal serotypes. Defective MBL2 polymorphisms did not predict increased IPD susceptibility in children born in Northern Europe.

A genome-wide association study identifies CDHR3 as a susceptibility locus for early childhood asthma with severe exacerbations

Asthma exacerbations are among the most frequent causes of hospitalization during childhood, but the underlying mechanisms are poorly understood. We performed a genome-wide association study of a specific asthma phenotype characterized by recurrent, severe exacerbations occurring between 2 and 6 years of age in a total of 1,173 cases and 2,522 controls. Cases were identified from national health registries of hospitalization, and DNA was obtained from the Danish Neonatal Screening Biobank. We identified five loci with genome-wide significant association. Four of these, GSDMB, IL33, RAD50 and IL1RL1, were previously reported as asthma susceptibility loci, but the effect sizes for these loci in our cohort were considerably larger than in the previous genome-wide association studies of asthma. We also obtained strong evidence for a new susceptibility gene, CDHR3 (encoding cadherin-related family member 3), which is highly expressed in airway epithelium. These results demonstrate the strength of applying specific phenotyping in the search for asthma susceptibility genes.

Genotyping whole‐genome‐amplified DNA from 3‐ to 25‐year‐old neonatal dried blood spot samples with reference to fresh genomic DNA

Stored surplus of dried blood spot (DBS) samples from neonatal screening programs constitute a vast potential for large genetic epidemiological studies. However, age of the samples and the small amounts of DNA available may limit their usage. In this study we validate genotyping accuracy and efficiency of whole-genome-amplified DNA (wgaDNA) obtained from stored DBS samples, with reference to fresh genomic DNA from the same individuals. DBS samples from 29 volunteers, stored for up to 25 years, in the Danish Neonatal Screening Biobank were included and three DNA extraction methods, each using one 3.2 mm disk, were evaluated. Four whole-genome amplification kits, and one re-amplification kit, were used. Thirty-one SNPs were genotyped using the Sequenom platform and the wgaDNA samples calls were compared with their references for accuracy and efficiency evaluation. The genotype calls done blinded by the user had in many setups a 100% call- and concordance rate. Our results showed that genotyping performance is dependent on the combination of extraction procedure and amplification method, whereas years of storage did not seem to influence in this study. Based on these results we conclude that DBS samples should be considered a reliable and potential resource for future genotyping studies.

High-Throughput Genotyping on Archived Dried Blood Spot Samples

The aim of this study was to investigate if dried blood spot (DBS) samples stored in the Danish Neonatal Screening Biobank (DNSB) and the Danish National Birth Cohort (DNBC) repository are useful for Illumina single-nucleotide polymorphism (SNP) genotyping. Genomic DNA (gDNA) was extracted from just one 3.2 mm DBS punch. The extract was subsequently whole-genome amplified to meet the required amounts of DNA for genotyping. For evaluation of the biobank samples, we included variable factors: time of storage, gDNA, and whole-genome amplified DNA (wgaDNA) concentrations and the Illumina quality metric (GenCall score). The custom 1152 SNP genotyping assay had a 68.5% locus success rate, which was close to the expected 70%. An effect of storage condition was seen in the DNSB samples stored from 1982 to 1987, whereas none was seen in the samples stored from 1988 to 1990. The genotyping quality of the DNBC samples was affected by type of filter paper. We here demonstrate that high-throughput Illumina genotyping can be performed successfully on wgaDNA made of gDNA extracted from only one 3.2 mm DBS disk. This validates the vast potential of existing biobanks in the study of the role of gene interactions in complex diseases.