Plasma lipidomics of monozygotic twins discordant for multiple sclerosis.

Blood biomarkers of multiple sclerosis (MS) can provide a better understanding of pathophysiology and enable disease monitoring. Here, we performed quantitative shotgun lipidomics on the plasma of a unique cohort of 73 monozygotic twins discordant for MS. We analyzed 243 lipid species, evaluated lipid features such as fatty acyl chain length and number of acyl chain double bonds, and detected phospholipids that were significantly altered in the plasma of co-twins with MS compared to their non-affected siblings. Strikingly, changes were most prominent in ether phosphatidylethanolamines and ether phosphatidylcholines, suggesting a role for altered lipid signaling in the disease.

Biomarker discovery in attention deficit hyperactivity disorder: RNA sequencing of whole blood in discordant twin and case-controlled cohorts.

BACKGROUND: A variety of DNA-based methods have been applied to identify genetic markers of attention deficit hyperactivity disorder (ADHD), but the connection to RNA-based gene expression has not been fully exploited. METHODS: Using well defined cohorts of discordant, monozygotic twins from the Michigan State University Twin Registry, and case-controlled ADHD cases in adolescents, the present studies utilized advanced single molecule RNA sequencing to identify expressed changes in whole blood RNA in ADHD. Multiple analytical strategies were employed to narrow differentially expressed RNA targets to a small set of potential biomarkers of ADHD. RESULTS: RNA markers common to both the discordant twin study and case-controlled subjects further narrowed the putative targets, some of which had been previously associated with ADHD at the DNA level. The potential role of several differentially expressed genes, including ABCB5, RGS2, GAK, GIT1 and 3 members of the galactose metabolism pathway (GALE, GALT, GALK1) are substantiated by prior associations to ADHD and by established mechanistic connections to molecular pathways relevant to ADHD and behavioral control. CONCLUSIONS: The convergence of DNA, RNA, and metabolic data suggests these may be promising targets for diagnostics and therapeutics in ADHD.

Developmental origins of cardiometabolic health outcomes in twins: A systematic review and meta-analysis.

BACKGROUND AND AIMS: Studies of twins can reduce confounding and provide additional evidence about the causes of disease, due to within-pair matching for measured and unmeasured factors. Although findings from twin studies are typically applicable to the general population, few studies have taken full advantage of the twin design to explore the developmental origins of cardiometabolic health outcomes. We aimed to systematically review the evidence from twin studies and generate pooled estimates for the effects of early-life risk factors on later-life cardiometabolic health. METHODS AND RESULTS: An initial search was conducted in March 2018, with 55 studies of twins included in the review. Risk of bias was assessed using the Newcastle-Ottawa Scale, and eligible studies were included in a meta-analysis, where pooled estimates were calculated. Twenty-six studies analysed twins as individuals, and found that higher birthweight was associated with lower SBP (ß = -2.02 mmHg, 95%CI: -3.07, -0.97), higher BMI (ß = 0.52 kg/m2, 95%CI: 0.20, 0.84) and lower total cholesterol (ß = -0.07 mmol/L, 95%CI: -0.11, -0.04). However, no associations were reported in studies which adjusted for gestational age. Few of the included studies separated their analyses into within-pair and between-pair associations. CONCLUSIONS: Early-life risk factors were associated with cardiometabolic health outcomes in twin studies. However, many estimates from studies in this review were likely to have been confounded by gestational age, and few fully exploited the twin design to assess the developmental origins of cardiometabolic health outcomes.

Monozygotic twins with familial hypercholesterolemia and high lipoprotein(a) levels leading to identical cardiovascular outcomes: Case report and review of the literature.

Homozygous familial hypercholesterolemia (HoFH) is a rare, autosomal dominant disease that leads to premature cardiovascular disease (CVD). Since monozygotic twins share the intrauterine environment and have the same age and gene profile, they could represent a very special resource for the investigation of the causes and the natural course of FH. This report is a description of 36-year-old monozygotic twin brothers with almost identical early coronary artery involvement due to FH concomitant with high lipoprotein(a) (Lpa) levels and a review of the literature. Sequence analysis revealed that the twins were homozygous for the LDLR c.1060+10G>A (rs12710260) mutation and heterozygous for the LDLR c.542C>T (rs557344672) mutations. Both were also homozygous for the c.1060+7T>C (rs2738442) and c.1586+53A>G (rs1569372) mutations in the LDLR gene as well as c.4265A>T (rs568413) mutations in the APOB gene. In the literature, there are 7 twin cases with reported FH, but none with high Lpa levels. The HoFH twins in this case report had lower low-density lipoprotein (LDL) cholesterol levels than expected (before treatment 204 and 223 mg/dL), with almost identical coronary involvement. Both had an extremely high Lpa level (308 and 272 nmol/L) with a very low coronary calcium score (16 AU) and a good response to statins (>60%). There was a history of the first CVD event occurring at nearly the same age (32-34 years) in the family. This could be an important aspect of FH families as a result of the similar timing of cumulative LDL exposure exceeding the threshold of CVD events. In conclusion, this first report of monozygotic HoFH twins with elevated Lpa levels and almost identical early coronary artery involvement at the same age provides evidence to substantiate the hypothesis of lifetime cholesterol burden/exposure.

Peripheral blood DNA methylation differences in twin pairs discordant for Alzheimer's disease.

BACKGROUND: Alzheimer's disease results from a neurodegenerative process that starts well before the diagnosis can be made. New prognostic or diagnostic markers enabling early intervention into the disease process would be highly valuable. Environmental and lifestyle factors largely modulate the disease risk and may influence the pathogenesis through epigenetic mechanisms, such as DNA methylation. As environmental and lifestyle factors may affect multiple tissues of the body, we hypothesized that the disease-associated DNA methylation signatures are detectable in the peripheral blood of discordant twin pairs. RESULTS: Comparison of 23 disease discordant Finnish twin pairs with reduced representation bisulfite sequencing revealed peripheral blood DNA methylation differences in 11 genomic regions with at least 15.0% median methylation difference and FDR adjusted p value ≤ 0.05. Several of the affected genes are primarily associated with neuronal functions and pathologies and do not display disease-associated differences in gene expression in blood. The DNA methylation mark in ADARB2 gene was found to be differentially methylated also in the anterior hippocampus, including entorhinal cortex, of non-twin cases and controls. Targeted bisulfite pyrosequencing of the DNA methylation mark in ADARB2 gene in 62 Finnish and Swedish twin pairs revealed that, in addition to the disease status, DNA methylation of this region is influenced by gender, age, zygosity, APOE genotype, and smoking. Further analysis of 120 Swedish twin pairs indicated that this specific DNA methylation mark is not predictive for Alzheimer's disease and becomes differentially methylated after disease onset. CONCLUSIONS: DNA methylation differences can be detected in the peripheral blood of twin pairs discordant for Alzheimer's disease. These DNA methylation signatures may have value as disease markers and provide insights into the molecular mechanisms of pathogenesis. We found no evidence that the DNA methylation marks would be associated with gene expression in blood. Further studies are needed to elucidate the potential importance of the associated genes in neuronal functions and to validate the prognostic or diagnostic value of the individual marks or marker panels.

DNA methylation signatures of monozygotic twins clinically discordant for multiple sclerosis.

Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system with a modest concordance rate in monozygotic twins, which strongly argues for involvement of epigenetic factors. We observe highly similar peripheral blood mononuclear cell-based methylomes in 45 MS-discordant monozygotic twins. Nevertheless, we identify seven MS-associated differentially methylated positions (DMPs) of which we validate two, including a region in the TMEM232 promoter and ZBTB16 enhancer. In CD4 + T cells we find an MS-associated differentially methylated region in FIRRE. Additionally, 45 regions show large methylation differences in individual pairs, but they do not clearly associate with MS. Furthermore, we present epigenetic biomarkers for current interferon-beta treatment, and extensive validation shows that the ZBTB16 DMP is a signature for prior glucocorticoid treatment. Taken together, this study represents an important reference for epigenomic MS studies, identifies new candidate epigenetic markers, and highlights treatment effects and genetic background as major confounders.

Discordant immune complete heart block and growth restriction in dichorionic twin pregnancy with permanent pacemaker implantation of an 1140 g neonate.

Fetal atrioventricular block is a rare pathology, mostly due to placental transmission of maternal SSA/Ro and SSB/La antibodies, and can lead to severe fetal or neonatal outcomes. We report a case of dichorionic, diamniotic twin pregnancy, with maternal SSA/Ro antibodies. Isolated complete atrioventricular block was diagnosed at 23 weeks in one fetus (Twin A), while the second fetus (Twin B) remained in normal sinus rhythm. Severe asymmetric intrauterine growth restriction occurred in Twin A. Delivery was by caesarean section at 32 + 2 weeks. Neonatal permanent pacemaker was inserted on the first day after birth in 1140 g neonate. Discordant heart block in twin pregnancy has already been reported in a few dichorionic pregnancies, but the pathway of discordant disease expression remains unclear. Extraction decision is a dilemma between cardiac failure prevention and prematurity associated twin morbidity. This case shows a successful pacing in a very low birth weight neonate.

Heterozygous familial hypercholesterolaemia in a pair of identical twins: a case report and updated review.

BACKGROUND: Familial hypercholesterolaemia (FH) is the most common inherited metabolic disease with an autosomal dominant mode of inheritance. It is characterised by raised serum levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-c), leading to premature coronary artery disease. Children with FH are subjected to early and enhanced atherosclerosis, leading to greater risk of coronary events, including premature coronary artery disease. To the best of our knowledge, this is the first report of a pair of monochorionic diamniotic identical twins with a diagnosis of heterozygous FH, resulting from mutations in both LDLR and ABCG8 genes. CASE PRESENTATION: This is a rare case of a pair of 8-year-old monochorionic diamniotic identical twin, who on family cascade screening were diagnosed as definite FH, according to the Dutch Lipid Clinic Criteria (DLCC) with a score of 10. There were no lipid stigmata noted. Baseline lipid profiles revealed severe hypercholesterolaemia, (TC = 10.5 mmol/L, 10.6 mmol/L; LDL-c = 8.8 mmol/L, 8.6 mmol/L respectively). Their father is the index case who initially presented with premature CAD, and subsequently diagnosed as FH. Family cascade screening identified clinical FH in other family members including their paternal grandfather who also had premature CAD, and another elder brother, aged 10 years. Genetic analysis by targeted next-generation sequencing using MiSeq platform (Illumina) was performed to detect mutations in LDLR, APOB100, PCSK9, ABCG5, ABCG8, APOE and LDLRAP1 genes. Results revealed that the twin, their elder brother, father and grandfather are heterozygous for a missense mutation (c.530C > T) in LDLR that was previously reported as a pathogenic mutation. In addition, the twin has heterozygous ABCG8 gene mutation (c.55G > C). Their eldest brother aged 12 years and their mother both had normal lipid profiles with absence of LDLR gene mutation. CONCLUSION: A rare case of Asian monochorionic diamniotic identical twin, with clinically diagnosed and molecularly confirmed heterozygous FH, due to LDLR and ABCG8 gene mutations have been reported. Childhood FH may not present with the classical physical manifestations including the pathognomonic lipid stigmata as in adults. Therefore, childhood FH can be diagnosed early using a combination of clinical criteria and molecular analyses.

Genetic and Early-Life Environmental Influences on Dental Caries Risk: A Twin Study.

OBJECTIVES: To explore the relative contributions of genetic and environmental influences on dental caries risk and to investigate fetal and developmental risk factors for dental caries. METHODS: We recruited children from 250 twin pregnancies midgestation and collected demographic, health, and phenotypic data at recruitment, 24 and 36 weeks' gestational age, birth and 18 months, and 6 years of age. 25-hydroxyvitamin D was quantified in mothers at 28 weeks' gestation and in infants at birth. Dental caries and enamel defects were measured at six years of age. We compared concordance for the presence of any caries and advanced caries in monozygotic and dizygotic twin pairs. To investigate environmental risk factors for caries, we fitted multiple logistic regression models using generalized estimating equations to adjust for twin correlation. RESULTS: A total of 345 twins underwent dental assessment, with 111 (32.2%) showing signs of any caries and 83 (24.1%) having advanced caries. There was no evidence of higher concordance in monozygotic twins compared with dizygotic twins, with a difference of 0.05 (95% confidence interval -0.14 to 0.25; P = .30) and 0.00 (95% confidence interval -0.26 to 0.26; P = .50) for any caries and advanced caries, respectively, suggesting that environmental factors, rather than genetics, are the predominant determinant of caries risk. After adjusting for potential confounders, lack of community water fluoridation, hypomineralized second primary molars, dichorionic placenta, and maternal obesity were associated with caries. CONCLUSIONS: Environmental rather than genetic factors drive dental caries risk and arise as early as prenatal life.

Serum bile acid patterns are associated with the presence of NAFLD in twins, and dose-dependent changes with increase in fibrosis stage in patients with biopsy-proven NAFLD.

BACKGROUND: The fasting-state serum bile acid profile in nonalcoholic fatty liver disease (NAFLD) has been reported to differ when nonalcoholic steatohepatitis is compared to nonalcoholic fatty liver. However, there are few data comparing changes in NAFLD vs non-NAFLD, or whether the bile acid profile differs according to the degree of fibrosis. AIM: To examine the serum bile acid profile across the entire spectrum of NAFLD. METHODS: We performed a cross-sectional analysis of two complementary cohorts: a Twin and Family cohort of 156 participants, and a biopsy-proven-NAFLD cohort of 156 participants with fasting bile acid profiling using liquid chromatography/mass spectrometry. RESULTS: In the Twin and Family cohort (mean age 46.3 years and body mass index (BMI) 26.6 kg/m2 ), 36 (23%) participants had NAFLD (magnetic resonance imaging proton density fat fraction ≥ 5%). Higher chenodeoxycholyl conjugates (9.0% vs 6.5%, P = 0.019) and lower glycohyocholate (1.2% vs 3.6%, P < 0.001) were observed in NAFLD compared to non-NAFLD-controls. In the biopsy-proven-NAFLD cohort (mean age 49.8 years, BMI 32.0 kg/m2 ), no differences in total bile acid were seen between nonalcoholic fatty liver vs nonalcoholic steatohepatitis. The total unconjugated bile acid significantly decreased across nonalcoholic steatohepatitis categories (P = 0.044). The distribution of stage of fibrosis was F0: 42.3%, F1: 32.7%, F2: 10.3%, F3: 8.3% and F4: 6.4%. The total serum bile acid increased with increase in fibrosis stage (P < 0.001). The primary conjugated bile acid proportion increased (P < 0.001) whereas unconjugated bile acid (P = 0.006), unconjugated cholyl (P < 0.001) and chenodeoxycholyl conjugates (P < 0.002) significantly decreased with increase in liver fibrosis stage. CONCLUSIONS: Fasting-state serum bile acid profile alterations are seen across the entire spectrum of NAFLD. The total serum bile acids did not differ significantly between NAFLD vs non-NAFLD and nonalcoholic fatty liver vs nonalcoholic steatohepatitis, but were significantly perturbed progressively as liver fibrosis increases.

Circulating, Cell-Free Micro-RNA Profiles Reflect Discordant Development of Dementia in Monozygotic Twins.

We aim to examine if circulating micro-RNA and cytokine levels associate with dementia diagnosis and cognitive scores. To test our hypothesis, we use plasma donated from 48 monozygotic twin pairs in 1997 and 46 micro-RNAs and 10 cytokines were quantified using microfluidic RT-qPCR and multiplex solid-phase immunoassays, respectively. Micro-RNA and cytokine profiling were examined for associations with dementia diagnoses in a longitudinal registry study or with cognitive scores at baseline. Thirty-six micro-RNAs and all cytokines were detected consistently. Micro-RNA profiles associate with diagnoses and cognitive scores at statistically significant levels while cytokine only showed trends pointing at chronic inflammation in twins having or developing dementia. The most notable findings were decreased miR-106a and miR-210, and increased miR-106b expression in twins with a dementia diagnosis. This pioneering evaluation of micro-RNA and cytokine and dementia diagnosis suggests micro-RNA targets in vasculogenesis, lipoprotein transport, and amyloid precursor protein genes.

Case report: an identical twin with Sertoli-Leydig cell tumor.

Our report details the workup and management of a 43-year-old woman with an identical twin who presented with 2 years of virilization and secondary amenorrhea. Serum total testosterone was elevated. An MRI did not identify adnexal or adrenal pathology. Subsequent ovarian vein sampling demonstrated unilateral testosterone elevation. The patient underwent laparoscopic unilateral oophorectomy resulting in the diagnosis of Sertoli-Leydig cell tumor (SLCT). Although SLCT is a rare sex-cord ovarian tumor, it is associated with endometrial hyperplasia and malignancy. Our goals are to review the workup of androgen-secreting tumors and discuss the clinical importance of the DICER1 mutation in the context of SLCT. In this case, an identical twin underwent DICER1 testing which was one of the essential steps in her clinical management.

Chimerism for 20q11.2 microdeletion of GDF5 explains discordant phenotypes in monochorionic-diamniotic twins.

Microdeletions of 20q11.2 are rare but have been associated with characteristic clinical findings. A 1.6 Mb minimal critical region has been identified that includes three OMIM genes: GDF5, EPB41L1, and SAMHD. Here we describe a male monozygotic, monochorionic-diamniotic twin pair with discordant phenotypes, one with multiple findings that overlap with those reported in 20q11.2 deletions, and the other unaffected. Microarray analysis revealed mosaicism for a 363 Kb deletion encompassing GDF5 in the peripheral blood of both twins, which was confirmed by FISH. Subsequent FISH on buccal cells identified the deletion only in the affected twin. The blood FISH findings were interpreted as representing chimerism resulting from anastomosis and the blood exchange between the twins in utero. The implications of this finding are discussed, as is the contribution of GDF5 to the associated clinical findings of 20q11.2 deletions.

Lipids and Adipokines in Cord Blood and at 72 h in Discordant Dichorionic Twins.

BACKGROUND: Intrauterine growth restriction (IUGR) is a risk factor for developing metabolic syndrome later in life. We explored whether adipokine concentrations in cord blood (CB) and on day 3 (D3) were related to impaired fetal growth and lipids in IUGR twins. PATIENTS AND METHODS: Thirty-six discordant (birth weight [BW] discordance ≥20% calculated in relation to the heavier co-twins) and 42 concordant (BW discordance ≤ 10%) twin pairs were included. RESULTS: In IUGR twins, both adiponectin/BW and triglyceride (TG) levels were significantly higher, while total cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol were lower in CB. On D3, both leptin and HDL-C levels were significantly lower and TG levels were significantly higher in IUGR twins. In the discordant group, the alterations in lipids were not related to any adipokine. CONCLUSIONS: IUGR is related to lower leptin level and proatherogenic lipid profile (higher TG and lower HDL-C), which are not influenced by adipokine at birth.

Angiogenesis-related biomarkers (sFlt-1/PlGF) in placental mesenchymal dysplasia.

Determination of the soluble fms-like tyrosine kinase-1 to placental growth factor ratio (sFlt-1/PlGF) in the maternal serum is expected to aid in the monitoring and decision-making process of women at risk for placental dysfunction. We report two cases of placental mesenchymal dysplasia (PMD) with sFlt-1/PlGF correlation. The first case is a dichorionic twin pregnancy with one fetus affected by PMD and Beckwith-Wiedemann syndrome in which a high value of sFlt-1/PlGF was found, coinciding with acute maternal and fetal wellbeing decline at 31 weeks. The second case corresponds to a singleton pregnancy diagnosed of PMD with normal sFlt-1/PlGF and favorable outcome.

Transcriptional and epigenetic phenomena in peripheral blood cells of monozygotic twins discordant for alzheimer's disease, a case report.

Target genes in Alzheimer's disease (AD) have been identified. In monozygotic twins discordant for AD we analysed the expression of selected genes, and their possible regulation by epigenetic mechanisms in peripheral blood mononuclear cells, possibly useful to discover biomarkers. Amyloid precursor protein, sirtuin 1 and peptidyl prolyl isomerase 1 gene expressions were highly up-regulated in the AD twin versus the healthy one. Consistently with sirtuin 1 role in controlling acetylation status, we observed a substantial reduction of the acetylation on histone 3 lysine 9, associated with gene transcription in the AD twin. Noteworthy in the AD twin we also observed an increased gene expression in two histone deacetylases (HDACs) isoforms: HDAC2 and HDAC9. A general DNA hypomethylation of all gene promoters studied was also observed in both twins. Our results unravel transcriptional and epigenetic differences potentially helpful to better understand environmental factors and phenotypic differences in monozygotic twins.

Positive Association Between Vitamin D Serum Levels and Naevus Counts.

Lower vitamin D serum levels are linked to increased melanoma risk and poorer survival. Naevus counts are associated with both melanoma risk and survival and to leucocyte telomere length. Vitamin D is also linked to telomere biology with higher levels of vitamin D in individuals with longer leucocyte telomere length despite adjusting for age. Using the TwinsUK data, we explored the association between naevus count, leucocyte telomere length and vitamin D serum levels. Increasing vitamin D levels were associated with increasing naevus count: serum levels were 73.3 nmol/l in individuals with less than 50 naevi compared to 78.8 nmol/l in individuals with more than 50 naevi (p?=?0.002). In the final regression model, using naevus count as a continuous variable, vitamin D remained associated with higher naevus counts despite adjustment for age, weight, height, season of sampling and twin relatedness (p?=?0.02). Further adjustment for leucocyte telomere length, decreased the magnitude of the association but it remained significant so leucocyte telomere length is not the sole driver of this association. Having large numbers of naevi is associated with higher vitamin D serum levels.