Cohort profile: The PreEclampsia, Angiogenesis, Cardiac dysfunction and Hypertension (PEACH) Study.

BACKGROUND: Hypertensive disorders of pregnancy (HDP) remain a leading cause of maternal morbidity and mortality worldwide, with implications for maternal and neonatal well-being in the short term and for long-term maternal cardiovascular health. Although the mechanisms behind HDP remain incompletely understood, evidence suggests that preeclampsia in particular is a syndrome with more than one distinct subtype. OBJECTIVES: The PEACH (PreEclampsia, Angiogenesis, Cardiac dysfunction, Hypertension) Study was established to identify new HDP subtyping systems reflecting aetiology and prognosis and to find markers of later cardiovascular disease risk associated with preeclampsia. POPULATION: The PEACH Study recruited pregnant women referred to two Copenhagen-area hospitals with suspected preeclampsia (mean gestational age at enrolment: 36.7 weeks) and a group of frequency-matched pregnant women planning delivery at the same hospitals and healthy when enrolled mid-pregnancy. DESIGN: Prospective, longitudinal pregnancy cohort. METHODS: Participants underwent repeated third-trimester blood sample collection, longitudinal cardiac function assessments using the USCOM-1A during the third trimester and at 1 year postpartum and collection of placental samples immediately after delivery. Medical information was abstracted from medical records and hospital databases. PRELIMINARY RESULTS: During 2016-2018, we recruited 1149 pregnant women, of whom 1101 were followed to delivery. Among 691 women enrolled with suspected preeclampsia, 310 and 172 developed preeclampsia and gestational hypertension respectively. Among 410 women with healthy pregnancies when enrolled mid-pregnancy, 37 later developed hypertensive disorders of pregnancy. Of 1089 women still in the cohort 1 year postpartum, 578 (53.1%) participated in the follow-up assessment. CONCLUSIONS: The PEACH Study's rich data from women with and without HDP will enable us to identify new, clinically useful HDP subtypes to aid in decision-making regarding monitoring and treatment. Continued postpartum follow-up will help us develop algorithms to identify women at risk of persistent postpartum cardiac dysfunction and later cardiovascular disease after pregnancies complicated by HDP.

Whole Genome Amplification from Blood Spot Samples.

Whole genome amplification is an invaluable technique when working with DNA extracted from blood spots, as the DNA obtained from this source often is too limited for extensive genetic analysis. Two techniques that amplify the entire genome are common. Here, both are described with focus on the benefits and drawbacks of each system. However, in order to obtain the best possible WGA result the quality of input DNA extracted from the blood spot is essential, but also time consumption, flexibility in format and elution volume and price of the technology are factors influencing system choice. Here, three DNA extraction techniques are described and the above aspects are compared between the systems.

New national Biobank of The Danish Center for Strategic Research on Type 2 Diabetes (DD2).

Long-term storage of biological samples from patients has become increasingly important in studies of disease control and treatment. The first nationwide Danish diabetes project, ie, The Danish Center for Strategic Research in Type II Diabetes (DD2), aims to improve treatment and the long-term outcome of patients with newly diagnosed type 2 diabetes (T2D). The DD2 project includes establishment of a biobank with samples from 50,000 patients with newly diagnosed T2D. This paper describes how blood and urine samples from 10,000 patients per year are collected, handled, and stored. The biobank includes whole blood, DNA, and plasma and urine samples, all frozen at -80°C. Sampling tubes have been standardized and are sent to hospital outpatient clinics and general practitioners where samples are taken, handled, aliquoted, and returned by mail overnight in standardized cryostorage tubes. When received at the biobank, samples are frozen without further treatment. From each patient, 24 cryostorage tubes are stored. Each tube is labeled with a barcode that links the data to other information available in a clinical databank registry. When patients are enrolled in DD2, a questionnaire is filled out and a quality monitoring system ensures that patients, samples, and questionnaires can be linked together at all times. The biobank is located at Vejle Hospital and the Danish National Biobank at Statens Serum Institut. As of the end of March 2012, samples from 1186 patients have been stored, and currently samples from 8-10 patients arrive per day. We have established the first national biobank in Denmark where blood, DNA, and plasma and urine samples from patients with newly diagnosed T2D are systematically collected and stored. This biobank enables sophisticated analysis of genetic variation and response to treatment, as well as disease marker studies that better classify disease status, progression, and complications.

No association of polymorphisms in human endogenous retrovirus K18 and CD48 with schizophrenia.

The human endogenous retrovirus HERV-K18 is located within intron 1 of CD48 on chromosome 1q and is still active in the human genome. Genetic variation in HERV-K18 single-nucleotide polymorphisms (SNPs) has previously been associated with an increased risk of schizophrenia (SZ) and with type 2 diabetes (T2D) among individuals with SZ. Here, we present a replication study of association of two SNPs in HERV-K18 and 19 tagSNPs in CD48 with (a) SZ and (b) T2D in patients with SZ in two Danish samples (total number of cases=750 and controls=1214). No association was found with SZ or with T2D among individuals with SZ for any of the investigated SNPs. However, one HERV-K18 SNP showed a tendency toward an association with T2D in younger SZ patients, in agreement with previous findings, but due to a very low sample size, this result needs to be further investigated.

Screening of congenital heart disease patients using multiplex ligation-dependent probe amplification: early diagnosis of syndromic patients.

Recurrent copy number variants (CNVs) are found in a significant proportion of patients with congenital heart disease (CHD) and some of these CNVs are associated with other developmental defects. In some syndromic patients, CHD may be the first presenting symptom, thus screening of patients with CHD for CNVs in specific genomic regions may lead to early diagnosis and awareness of extracardiac symptoms. We designed a multiplex ligation-dependent probe amplification (MLPA) assay specifically for screening of CHD patients. The MLPA assay allows for simultaneous analysis of CNVs in 25 genomic regions previously associated with CHD. We screened blood samples from 402 CHD patients and identified 14 rare CNVs in 13 (3.2%) patients. Five CNVs were de novo and six where inherited from a healthy parent. The MLPA screen led to early syndrome diagnosis in two of these patients. We conclude that the MLPA assay detects clinically relevant CNVs and suggest that it could be used within pediatric cardiology as a first tier screen to detect clinically relevant CNVs and identify syndromic patients at an early stage.

Chromosome 22q11.2 duplication is rare in a population-based cohort of Danish children with cardiovascular malformations.

The prevalence of the 22q11.2 duplication is unknown in children with cardiovascular malformations (CVMs). As most individuals with the duplication are detected in the search for other conditions, especially the 22q11.2 deletion, CVMs associated with the duplication are subject to referral bias. We circumvented this bias by investigating the prevalence of the 22q11.2 duplication in a population-based cohort of children with CVMs. The study population was defined as children born in 2000-2008, who were registered in the Danish National Patient Registry with a diagnosis of CVM from one of the two national university departments of pediatric cardiology. Sensitive multiplex ligation-dependent probe amplification was performed on dried blood spot samples from each individual's neonatal screening test. The study population consisted of 2,952 children with CVMs, 2,424 of whom were eligible for genetic testing; 13 individuals (0.5% [0.3-0.9%]) carried the duplication. Nine individuals (69%) had not previously been tested for a copy number variation on chromosome 22q11.2 in the clinical setting for children with CVMs. We conclude that 22q11.2 duplication is rare in children with CVMs, and is primarily found in malformations that are also associated with the 22q11.2 deletion.

The prevalence of chromosome 22q11.2 deletions in 2,478 children with cardiovascular malformations. A population-based study.

Deletion of chromosome 22q11.2 is considered one of the most frequent genetic causes of cardiovascular malformations. It is frequently associated with conotruncal malformations, but may also be present among patients with nonconotruncal malformations. The aim of the present study was to establish the prevalence of the 22q11.2 deletion in an unselected population-based cohort of children with various cardiovascular malformations. The study population was defined as children born in 2000-2008 who were registered in the Danish National Patient Registry with a diagnosis of cardiovascular malformation from one of the two national departments of pediatric cardiology. Sensitive multiplex ligation-dependent probe amplification was performed on dried blood spot samples from each individual's neonatal screening test. Of 2,952 children with cardiovascular malformations, 2,478 were eligible for genetic testing. A total of 46 individuals (1.9% [1.4-2.5%]) carried the deletion, with the highest prevalence among individuals registered with interrupted aortic arch (22% [11-40]). The most frequent diagnoses among individuals carrying the deletion were tetralogy of Fallot (n = 15) and ventricular septal defect (n = 15). One in four cases had not been diagnosed in the usual clinical setting. The prevalence of 22q11.2 deletions in an unselected population-based cohort of children with cardiac malformations was 1.9% [1.4-2.5%]. Genetic testing of every individual registered with a conotruncal malformation would have achieved a diagnostic sensitivity of 70% in the present cohort. Prospective studies outlining testing recommendations in children with ventricular septal defect are warranted.

Children diagnosed with congenital cardiac malformations at the national university departments of pediatric cardiology: positive predictive values of data in the Danish National Patient Registry.

INTRODUCTION: The present study was conducted to establish the positive predictive value of congenital cardiac malformation diagnoses registered in the Danish National Patient Registry (NPR), thereby exploring whether the NPR can serve as a valid tool for epidemiologic studies of congenital cardiac malformations. MATERIALS AND METHODS: The study population comprised every individual born from 2000 to 2008 who was registered in the NPR with a congenital cardiac malformation diagnosis and treated at one of the two national departments of pediatric cardiology. Positive predictive values were established comparing NPR information with the clinical record of each individual. RESULTS: A total of 2952 patients with a total of 3536 diagnoses were eligible for validation. Review of their clinical records unveiled no patient without cardiac malformation. In 98% (98%-99%) of the cases, the NPR diagnosis could be found as the discharge diagnosis in the patient's clinical record, and in 90% (89%-91%) of the cases the NPR diagnosis was considered a true reflection of the patient's actual malformation. CONCLUSIONS: Our study verifies that the present study population retrieved from the NPR is a valid tool for epidemiological research within the topic of congenital cardiac malformations, given that the research question is not dependent on a fully established sensitivity of the NPR. Precautions should be made regarding cardiac malformations characterized by low prevalence or poor predictive values, and the reported validity should not be extrapolated beyond the study period.

Dual association of a TRKA polymorphism with schizophrenia.

OBJECTIVE: An interaction between predisposing genes and environmental stressors is thought to underlie the neurodevelopmental disorder schizophrenia. In a targeted gene screening, we previously found that the minor allele of the single nucleotide polymorphism (SNP) rs6336 in the neurotrophic tyrosine kinase receptor 1 (NTRK1/TRKA) gene is associated with schizophrenia as a risk factor. METHODS: We genotyped the TRKA SNP in a total of eight independent Caucasian schizophrenia case-control groups. RESULT: Remarkably, although in five of the groups a higher frequency of the risk allele was indeed found in the patients compared with the controls, in the three other groups the SNP acted as a protective factor. CONCLUSION: An intriguing possibility is that this dual character of the TRKA SNP is caused by its interaction with endophenotypic and/or epistatic factors.

A genome-wide association study of Hodgkin's lymphoma identifies new susceptibility loci at 2p16.1 (REL), 8q24.21 and 10p14 (GATA3).

To identify susceptibility loci for classical Hodgkin's lymphoma (cHL), we conducted a genome-wide association study of 589 individuals with cHL (cases) and 5,199 controls with validation in four independent samples totaling 2,057 cases and 3,416 controls. We identified three new susceptibility loci at 2p16.1 (rs1432295, REL, odds ratio (OR) = 1.22, combined P = 1.91 × 10(-8)), 8q24.21 (rs2019960, PVT1, OR = 1.33, combined P = 1.26 × 10(-13)) and 10p14 (rs501764, GATA3, OR = 1.25, combined P = 7.05 × 10(-8)). Furthermore, we confirmed the role of the major histocompatibility complex in disease etiology by revealing a strong human leukocyte antigen (HLA) association (rs6903608, OR = 1.70, combined P = 2.84 × 10(-50)). These data provide new insight into the pathogenesis of cHL.

Genetic variation in chromosomal translocation breakpoint and immune function genes and risk of non-Hodgkin lymphoma.

BACKGROUND: Tumor necrosis factor (TNF) and interleukin 10 (IL10) are promising candidate susceptibility genes for non-Hodgkin lymphoma (NHL). Chromosomal translocation breakpoint genes are of interest, given their documented involvement in lymphoma progression. METHODS: We analyzed 11 polymorphisms in BCL2, CCND1, MYC, TNF, and IL10 in a large, population-based, Danish-Swedish case-control study including 2,449 NHL cases and 1,980 controls. Relative risk of NHL was computed as odds ratios (OR). RESULTS: There was no clear evidence of associations between variants in BCL2, CCND1, and MYC and risk of NHL overall or subtypes. TNF rs1800629 was associated with risk of NHL (OR 1.53, 95% confidence interval, CI, 1.06-2.19 for minor allele homozygosity), T-cell lymphoma (OR 2.54, CI 1.27-5.09) and mantle cell lymphoma (OR 2.84, CI 1.38-5.87). IL10 rs1800890 was associated with risk of diffuse large B-cell lymphoma (OR 1.41, CI 1.08-1.85 for minor allele homozygosity) and mantle cell lymphoma (OR 1.77, CI 1.04-3.00). We did not replicate a previously reported interaction with autoimmunity. CONCLUSIONS: We found no support for a role of the studied variants in BCL2, CCND1, or MYC in risk of NHL or subtypes, but we provide further evidence of putative susceptibility loci in TNF and IL10 for specific NHL subtypes.

A non-synonymous variant in SLC30A8 is not associated with type 1 diabetes in the Danish population.

Genome-wide association scans in type 2 diabetes (T2D) have identified a risk variant, rs13266634 (Arg325Trp), in SLC30A8 on chromosome 8. SLC30A8 encodes a beta-cell specific zinc-ion transporter and rs13266634 has been shown to affect insulin secretion. Recently, autoantibodies for Slc30A8 with high predictive value were demonstrated in individuals with type 1 diabetes (T1D), making this gene an interesting T1D candidate gene. We genotyped rs13266634 in 3008 cases and controls and 246 families from Denmark. Association to T1D could not be demonstrated.

Multiplex ligation-dependent probe amplification technique for copy number analysis on small amounts of DNA material.

The multiplex ligation-dependent probe amplification (MLPA) technique is a sensitive technique for relative quantification of up to 50 different nucleic acid sequences in a single reaction, and the technique is routinely used for copy number analysis in various syndromes and diseases. The aim of the study was to exploit the potential of MLPA when the DNA material is limited. The DNA concentration required in standard MLPA analysis is not attainable from dried blood spot samples (DBSS) often used in neonatal screening programs. A novel design of MLPA probes has been developed to permit for MLPA analysis on small amounts of DNA. Six patients with congenital adrenal hyperplasia (CAH) were used in this study. DNA was extracted from both whole blood and DBSS and subjected to MLPA analysis using normal and modified probes. Results were analyzed using GeneMarker and manual Excel analysis. A total number of 792 ligation events were analyzed. In DNA extracted from dried blood spot samples, 99.1% of the results were accurate compared to 99.9% of the results obtained in DNA from whole blood samples. This study clearly demonstrates that MLPA reactions with modified probes are successful and reliable with DNA concentrations down to 0.3 ng/microL (1.6 ng total). This broadens the diagnostic perspectives of samples of DBSS allowing for copy number variation analysis in general and particularly testing for CAH.

Whole genome amplification on DNA from filter paper blood spot samples: an evaluation of selected systems.

As the number of single-nucleotide polymorphism (SNP) screening and other mutation scanning studies have increased explosively, following the development of high-throughput instrumentation, it becomes even more important to have sufficient template DNA. The source of DNA is often limited, especially in epidemiological studies, which require many samples as well as enough DNA to perform numerous SNP screenings or mutation scannings. Therefore, the aim is to solve the problem of stock DNA limitation. This need has been an important reason for the development of whole genome amplification (WGA) methods. Several systems are based on Phi29 polymerase multiple displacement amplification (MDA) or on DNA fragmentation (OmniPlex). Using TaqMan SNP genotyping assays, we have tested four WGA systems -- AmpliQ Genomic Amplifier Kit, GenomiPhi, Repli-g, and GenomePlex -- on DNA extracted from Guthrie cards to evaluate the amplification bias, concordance- and call rates, cost efficiency, and flexibility. All systems successfully amplified picograms of DNA from Guthrie cards to micrograms of product without loss of heterozygosity and with minimal allelic bias. A modified AmpliQ set up was chosen for further evaluation. In all, 2,000 SNP genotyping results from amplified and nonamplified samples were compared and the concordance rates between the samples were 99.7%. The call rate using the TaqMan system was 99.8%. DNA extracted from Guthrie cards and amplified with one of the four evaluated WGA systems is applicable in epidemiological genetic screenings. System choice should be based on requirements for system flexibility, product yield, and use in subsequent analysis.