Clonal hematopoiesis in elderly twins: concordance, discordance, and mortality.

Clonal hematopoiesis (CH) of indeterminate potential (CHIP) is defined by mutations in myeloid cancer-associated genes with a variant allele frequency of at least 2%. Recent studies have suggested a possible genetic predisposition to CH. To further explore this phenomenon, we conducted a population-based study of 594 twins from 299 pairs aged 73 to 94 years, all with >20 years' follow-up. We sequenced DNA from peripheral blood with a customized 21-gene panel at a median coverage of 6179X. The casewise concordance rates for mutations were calculated to assess genetic predisposition. Mutations were identified in 214 (36%) of the twins. Whereas 20 twin pairs had mutations within the same genes, the exact same mutation was only observed in 2 twin pairs. No significant difference in casewise concordance between monozygotic and dizygotic twins was found for any specific gene, subgroup, or CHIP mutations overall, and no significant heritability could be detected. In pairs discordant for CHIP mutations, we tested if the affected twin died before the unaffected twin, as a direct measurement of the association of having CH when controlling for familial factors. A total of 127 twin pairs were discordant for carrying a mutation, and in 61 (48%) cases, the affected twin died first (P = .72). Overall, we did not find a genetic predisposition to CHIP mutations in this twin study. The previously described negative association of CHIP mutations on survival could not be confirmed in a direct comparison among twin pairs that were discordant for CHIP mutations.

Genetic contribution to the etiology of Achilles tendon rupture. A Danish nationwide register study of twins.

BACKGROUND: It is unknown if genetics contribute to the etiology of acute Achilles tendon rupture (ATR). The aims of the present study were, 1) To calculate the concordance rate for monozygotic (MZ) twins and same-sex dizygotic (SSDZ) twins and 2) to estimate the heritability of ATR. METHODS: The study was performed as a registry study using the Danish Twin Registry and the Danish National Patient Registry. RESULTS: The study sample consisted of 85,534 twins born from 1895 to 1995. Of these, 572 (0.67%) were registered with ATR in the period from 1994 to 2014. The concordance rate was 8.1% (95% CI 1.4-14.7%) for MZ twins and 4.3% (95% CI 0.7-7.9%) for SSDZ twins. The heritability of ATR was 47% (95% CI 31-62%). CONCLUSION: This study found that genetics contribute substantially to the etiology of ATR with an estimated heritability of the liability to ATR of approximately 50%. The finding generates the hypothesis that genetics play a role in the pathological changes that occur in the Achilles tendon before a rupture. The risk of ATR for a twin within a 20 year period, if the co-twin has had an ATR, was 8% for MZ twins and 4% for SSDZ twins.

The Danish Twin Registry: An Updated Overview.

The Danish Twin Registry (DTR) was established in the 1950s, when twins born from 1870 to 1910 were ascertained, and has since been extended to include twins from birth cohorts until 2009. The DTR currently comprises of more than 175,000 twins from the 140 birth cohorts. This makes the DTR the oldest nationwide twin register and among the largest in the world. The combination of data from several surveys, including biological samples and repeated measurements on the same individuals, and data from Danish national registers provides a unique resource for a wide range of twin studies. This article provides an updated overview of the data in the DTR: First, we provide a summary of the establishment of the register, the different ascertainment methods and the twins included; then follows an overview of major surveys conducted in the DTR since 1994 and a description of the DTR biobank, including a description of the molecular data created so far; finally, a short description is given of the linkage to Danish national registers at Statistics Denmark and some recent examples of studies using the various data resources in the DTR are highlighted.

Maternal alcohol binge-drinking in the first trimester and the risk of orofacial clefts in offspring: a large population-based pooling study.

Using individual participant data from six population-based case-control studies, we conducted pooled analyses to examine maternal alcohol consumption and the risk of clefts among >4600 infants with cleft lip only, cleft lip with cleft palate, or cleft palate only and >10,000 unaffected controls. We examined two first-trimester alcohol measures: average number of drinks/sitting and maximum number of drinks/sitting, with five studies contributing to each analysis. Study-specific odds ratios (ORs) were estimated using logistic regression and pooled to generate adjusted summary ORs. Across studies, 0.9-3.2 % of control mothers reported drinking an average of 5+ drinks/sitting, while 1.4-23.5 % reported drinking a maximum of 5+ drinks/sitting. Compared with non-drinkers, mothers who drank an average of 5+ drinks/sitting were more likely to deliver an infant with cleft lip only (pooled OR 1.48; 95 % confidence intervals 1.01, 2.18). The estimate was higher among women who drank at this level 3+ times (pooled OR 1.95; 1.23, 3.11). Ever drinking a maximum of 5+ drinks/sitting and non-binge drinking were not associated with cleft risk. Repeated heavy maternal alcohol consumption was associated with an increased risk of cleft lip only in offspring. There was little evidence of increased risk for other cleft types or alcohol measures.

Ethnic variation in oral cleft occurrence in denmark 1981-2002.

Objective : To examine differences in oral cleft (OC) occurrence based on maternal only and parental country of origin in Denmark from 1981 to 2002. Methods : Data on all live births from the Danish Medical Birth Register from 1981 to 2002 were linked with the Danish Facial Cleft Database. Cleft cases were categorized into isolated and nonisolated cleft lip with or without palate (CL/P) and cleft palate only (CP). Birth prevalence was calculated as cases per 1,000 live born children by maternal country of origin, world region, and mixed parental groups. Results : We identified 3094 OC cases among 1,319,426 live births. Danish-born women had an OC birth prevalence of 2.38 with a 95% confidence interval (CI) (2.29-2.47) and foreign-born women a significant lower prevalence of 2.01 (CI, 1.77-2.27). This difference was explained by a lower isolated CL/P birth prevalence among foreign-born women of 0.97 (CI, 0.81-1.16) versus 1.35 (CI, 1.28-1.41). No significant differences were seen for the remaining subtypes. Parents with the same foreign country of origin had a lower overall OC (1.63; CI, 1.35-1.94) and isolated CL/P (0.76; CI, 0.57-0.99) birth prevalence than Danish-born parents. This was not the case for any of the mixed parental groups. Overall and subtype prevalence rates varied according to maternal categories of world region. Conclusion : In this study we found differences in OC occurrence among all live births in the Danish population based on maternal country of origin from 1981 to 2002. Danish-born women had higher OC and isolated CL/P birth prevalence compared with foreign-born women.

Heritability and circulating concentrations of pregnancy-associated plasma protein-A and stanniocalcin-2 in elderly monozygotic and dizygotic twins.

Introduction: Pregnancy-associated plasma protein-A (PAPP-A) is an IGF-activating enzyme suggested to influence aging-related diseases. However, knowledge on serum PAPP-A concentration and regulation in elderly subjects is limited. Therefore, we measured serum PAPP-A in elderly same-sex monozygotic (MZ) and dizygotic (DZ) twins, as this allowed us to describe the age-relationship of PAPP-A, and to test the hypothesis that serum PAPP-A concentrations are genetically determined. As PAPP-A is functionally related to stanniocalcin-2 (STC2), an endogenous PAPP-A inhibitor, we included measurements on STC2 as well as IGF-I and IGF-II. Methods: The twin cohort contained 596 subjects (250 MZ twins, 346 DZ twins), whereof 33% were males. The age ranged from 73.2 to 94.3 (mean 78.8) years. Serum was analyzed for PAPP-A, STC2, IGF-I, and IGF-II by commercial immunoassays. Results: In the twin cohort, PAPP-A increased with age (r=0.19; P<0.05), whereas IGF-I decreased (r=-0.12; P<0.05). Neither STC2 nor IGF-II showed any age relationship. When analyzed according to sex, PAPP-A correlated positively with age in males (r=0.18; P<0.05) and females (r=0.25; P<0.01), whereas IGF-I correlated inversely in females only (r=-0.15; P<0.01). Males had higher levels of PAPP-A (29%), STC2 (18%) and IGF-I (19%), whereas serum IGF-II was 28% higher in females (all P<0.001). For all four proteins, within-pair correlations were significantly higher for MZ twins than for DZ twins, and they demonstrated substantial and significant heritability, which after adjustment for age and sex averaged 59% for PAPP-A, 66% for STC2, 58% for IGF-I, and 52% for IGF-II. Discussion: This twin study confirms our hypothesis that the heritability of PAPP-A serum concentrations is substantial, and the same is true for STC2. As regards the age relationship, PAPP-A increases with age, whereas STC2 remains unchanged, thereby supporting the idea that the ability of STC2 to inhibit PAPP-A enzymatic activity decreases with increasing age.

Association of Trauma With Long-Term Risk of Death and Immune-Mediated or Cancer Disease in Same-Sex Twins.

Importance: Immediate consequences of trauma include a rapid and immense activation of the immune system, whereas long-term outcomes include premature death, physical disability, and reduced workability. Objective: To investigate if moderate to severe trauma is associated with long-term increased risk of death or immune-mediated or cancer disease. Design, Setting, and Participants: This registry-based, matched, co-twin control cohort study linked the Danish Twin Registry and the Danish National Patient Registry to identify twin pairs in which 1 twin had been exposed to severe trauma and the other twin had not from 1994 to 2018. The co-twin control design allowed for matching on genetic and environmental factors shared within twin pairs. Exposure: Twin pairs were included if 1 twin had been exposed to moderate to severe trauma and the other twin had not (ie, co-twin). Only twin pairs where both twins were alive 6 months after the trauma event were included. Main Outcome and Measure: Twin pairs were followed up from 6 months after trauma until 1 twin experienced the primary composite outcome of death or 1 of 24 predefined immune-mediated or cancer diseases or end of follow-up. Cox proportional hazards regression was used for intrapair analyses of the association between trauma and the primary outcome. Results: A total of 3776 twin pairs were included, and 2290 (61%) were disease free prior to outcome analysis and were eligible for the analysis of the primary outcome. The median (IQR) age was 36.4 (25.7-50.2) years. The median (IQR) follow-up time was 8.6 (3.8-14.5) years. Overall, 1268 twin pairs (55%) reached the primary outcome; the twin exposed to trauma was first to experience the outcome in 724 pairs (32%), whereas the co-twin was first in 544 pairs (24%). The hazard ratio for reaching the composite outcome was 1.33 (95% CI, 1.19-1.49) for twins exposed to trauma. Analyses of death or immune-mediated or cancer disease as separate outcomes provided hazard ratios of 1.91 (95% CI, 1.68-2.18) and 1.28 (95% CI, 1.14-1.44), respectively. Conclusion and Relevance: In this study, twins exposed to moderate to severe trauma had significantly increased risk of death or immune-mediated or cancer disease several years after trauma compared with their co-twins.

The effects of oral clefts on hospital use throughout the lifespan.

BACKGROUND: Oral clefts are one of the most common birth defects worldwide. They require multiple healthcare interventions and add significant burden on the health and quality of life of affected individuals. However, not much is known about the long term effects of oral clefts on health and healthcare use of affected individuals. In this study, we evaluate the effects of oral clefts on hospital use throughout the lifespan. METHODS: We estimate two-part regression models for hospital admission and length of stay for several age groups up to 68 years of age. The study employs unique secondary population-based data from several administrative inpatient, civil registration, demographic and labor market databases for 7,670 individuals born with oral clefts between 1936 and 2002 in Denmark, and 220,113 individuals without oral clefts from a 5% random sample of the total birth population from 1936 to 2002. RESULTS: Oral clefts significantly increase hospital use for most ages below 60 years by up to 233% for children ages 0-10 years and 16% for middle age adults. The more severe cleft forms (cleft lip with palate) have significantly larger effects on hospitalizations than less severe forms. CONCLUSIONS: The results suggest that individuals with oral clefts have higher hospitalization risks than the general population throughout most of the lifespan.

Reassessing the evidence of a survival advantage in Type 2 diabetes treated with metformin compared with controls without diabetes: a retrospective cohort study.

BACKGROUND: Previous research has suggested that individuals with Type 2 diabetes and initiated on metformin monotherapy present with a survival advantage compared with the general population without diabetes. This finding has generated considerable interest in the prophylactic use of metformin against age-related morbidity. METHODS: Utilizing Danish National Health Registers, we assessed differences in survival associated with metformin monotherapy for Type 2 diabetes compared with no diagnosis of diabetes in both singleton and discordant twin populations between 1996 and 2012. Data were analysed in both nested case-control and matched cohort study designs, with incidence rate ratios (IRRs) and hazard ratios estimated using conditional logistic regression and Cox proportional hazards regression, respectively. RESULTS: In case-control pairs matched on birth year and sex or co-twin (sex, birth year and familial factors), incident Type 2 diabetes with treatment by metformin monotherapy initiation compared with no diagnosis of diabetes was associated with increased mortality in both singletons (IRR = 1.52, 95% CI: 1.37, 1.68) and discordant twin pairs (IRR = 1.90, 95% CI: 1.35, 2.67). After adjusting for co-morbidities and social indicators, these associations were attenuated to 1.32 (95% CI: 1.16, 1.50) and 1.64 (95% CI: 1.10, 2.46), respectively. Increased mortality was observed across all levels of cumulative use and invariant to a range of study designs and sensitivity analyses. CONCLUSIONS: Treatment initiation by metformin monotherapy in Type 2 diabetes was not associated with survival equal or superior to that of the general population without diabetes. Our contrasting findings compared with previous research are unlikely to be the result of differences in epidemiological or methodological parameters.

Autoantibodies to folate receptor alpha during early pregnancy and risk of oral clefts in Denmark.

The objective of this study was to determine whether IgG and IgM autoantibodies to folate receptor alpha (FRalpha) in pregnant women are associated with an increased risk of oral cleft-affected offspring. A case-control study nested in the prospective Danish National Birth Cohort (100,418 pregnancies, enrolled during 1997-2003) was done. Hundred eighty-five children were born with an oral cleft. Maternal serum from their mothers (cases) was compared with maternal serum from 779 randomly selected mothers of nonmalformed children (controls). We found that the average level of FRalpha IgG autoantibodies did not differ significantly among cases and controls (p = 0.71). Slightly higher levels of FRalpha IgM autoantibodies were found among controls compared with cases. This was, however, not statistically significant (p = 0.06), except for mothers of children with isolated cleft lip (p = 0.04). Blocking of folate binding to FR was similar among cases and controls (p = 0.54). The results did not change when stratifying into the cleft subgroups, nor when only isolated oral cleft cases were considered. In conclusion, high maternal autoantibody levels and blocking of folate binding to FRalpha in maternal serum during pregnancy are not associated with an increased risk of oral clefts in the offspring in this population-based cohort.

Comparison of Late Mortality Among Twins Versus Singletons With Congenital Heart Defects.

In 2014, in the United States, nearly 7% of newborns were twins. Congenital heart defects (CHDs) are more frequent in both monozygotic and dizygotic twins than in singletons. Still, the longer-term prognosis for CHD twins is unknown. Here we assess the mortality pattern for CHD twins up to age 36 years and compare it with that for non-CHD twins, non-CHD co-twins, and CHD singletons. We identified all twins and a 5% random sample of all singletons born in Denmark from 1977 to 2009 by linking Danish national population and health registers. CHD cases were defined as subjects having a primary inpatient diagnosis of CHD (excluding preterm ductus) within the first year of life, and mortality was assessed through 2013. Among 63,362 live-born twin individuals, a total of 373 twins (0.59%) had a CHD diagnosis, whereas the corresponding numbers for singletons were 383 of 98,647 (0.39%). During the follow-up, 82 (22.0%) CHD twins died compared with 91 (23.8%) CHD singletons (p = 0.56). Despite a 5 times higher proportion of prematurity, CHD twins had a tendency toward only a moderately increased neonatal mortality compared with CHD singletons (hazard ratio 1.5, 95% confidence interval 0.94 to 2.5), and after the neonatal period up to age 36 the tendency was reversed (hazard ratio 0.8, 95% confidence interval 0.5 to 1.2). A potential underlying mechanism for this mortality pattern is selective intrauterine and neonatal mortality of twins with the most severe CHD. In conclusion, the study indicates that the overall survival prognosis for CHD twins is similar to that of CHD singletons.

Use of Psychotropic Medications and Visits to Psychiatrists and Psychologists among Individuals with Nonsyndromic Oral Clefts: A Population-Based Cohort Study.

BACKGROUND: Oral clefts (OCs) are among the most common congenital malformations and can have a large impact on the life of the affected individual. Research findings regarding the psychological and psychosocial consequences of OC are inconclusive. METHODS: Using Danish nationwide registers, we investigated redeemed prescriptions of psychotropic medication during 1996 to 2012 and visits to psychiatrists and psychologists during 1996 to 2011 among individuals born with nonsyndromic OC in Denmark between 1936 and 2009 and a comparison cohort of individuals without OC. This includes 8244 individuals with OC and 82,665 individuals without OC. RESULTS: The Cox regression analysis revealed 12% (95% confidence interval [CI], 7 to 16%) increased risk of using any psychotropic medication for individuals with OC. When examining by cleft type, higher risks for medication use were observed in individuals with cleft lip and palate (CLP) or cleft palate (CP) only. The largest increased relative risk was found for use of antipsychotics and stimulants for individuals with CP followed by use of antipsychotics for individuals with CLP. We found increased risk of visits to psychiatrists for individuals with CP and no increased risk for visits to psychologists for either group. CONCLUSIONS: This study indicates that a small group of individuals with nonsyndromic OC, in particular those with palatal involvement, have greater risk of using psychotropic medications. However, elevated use was also observed among younger individuals with cleft lip (CL) only. There seems to be only a modest increase in visits to health professionals for psychological reasons. Undiagnosed syndromes (e.g., 22q11 deletion syndrome), may, however, contribute to an overestimation of the associations. Birth Defects Research 109:824-835, 2017. © 2017 Wiley Periodicals, Inc.

Psychiatric Diagnoses in Individuals with Non-Syndromic Oral Clefts: A Danish Population-Based Cohort Study.

BACKGROUND: The aim of this study was to investigate the risk of psychiatric diagnoses in individuals with non-syndromic oral clefts (OC) compared with individuals without OC, including ages from 1 to 76 years. METHODS: Linking four Danish nationwide registers, we investigated the risk of psychiatric diagnoses at Danish psychiatric hospitals during the period 1969-2012 for individuals born with non-syndromic OC in Denmark 1936-2009 compared with a cohort of 10 individuals without OC per individual with OC, matched by sex and birth year. The sample included 8,568 individuals with OC, observed for 247,821 person-years, and 85,653 individuals without OC followed for 2,501,129 person-years. RESULTS: A total of 953 (11.1%) of the individuals with OC (9.6% for cleft lip (CL), 10.8% for cleft lip and palate (CLP) and 13.1% for cleft palate (CP)) and 8,117 (9.5%) in the comparison group had at least one psychiatric diagnosis. Cox proportional hazard regression model revealed that individuals with OC had significantly higher risk of a psychiatric diagnosis (hazard ratio (HR) = 1.19, 95% CI: 1.12-1.28). When examining cleft type, no difference was found for CL (HR = 1.03, 95% CI: 0.90-1.17), but CLP was associated with a small increased risk (HR = 1.13, 95% CI: 1.01-1.26), whereas individuals with CP had the largest increased risk (HR = 1.45, 95% CI: 1.30-1.62). The largest differences were found in schizophrenia-like disorders, mental retardation and pervasive developmental disorders, but we found no increased risk of mood disorders and anxiety-related disorders. CONCLUSION: Individuals with non-syndromic OC had significantly higher risk of psychiatric diagnoses compared with individuals without OC. However, the elevated risk was observed for individuals with CLP and CP but not for individuals with CL and the absolute risk increase was modest.

Long-term effects of oral clefts on health care utilization: a sibling comparison.

Oral clefts are among the most common birth defects affecting thousands of newborns each year, but little is known about their potential long-term consequences. In this paper, we explore the impact of oral clefts on health care utilization over most of the lifespan. To account for time-invariant unobservable parental characteristics, we compare affected individuals with their own unaffected siblings. The analysis is based on unique data comprising the entire cohort of individuals born with oral clefts in Denmark tracked until adulthood in administrative register data. We find that children with oral clefts use more health services than their unaffected siblings. Additional results show that the effects are driven primarily by congenital malformation-related hospitalizations and intake of anti-infectives. Although the absolute differences in most health care utilization diminish over time, affected individuals have slightly higher utilization of some health care services in adulthood (particularly for diseases of the nervous and respiratory system). These results have important implications for affected individuals, their families, and their health professionals.

Risk of breast cancer in families with cleft lip and palate.

PURPOSE: To test whether female subjects in families with cleft lip and/or palate (CL/P) have an increased risk of breast cancer. METHODS: By using the Danish Facial Cleft Registry, we identified female subjects with CL/P, mothers of children with CL/P, and sisters to CL/P cases for the Danish birth cohorts 1911-1975. These subjects were compared with a 5% random sample of these cohorts regarding the incidence and age of onset for breast cancer registered in the Danish Hospital Discharge Register 1977-2005. RESULTS: Examining 48,404 person-years for 1809 female CL/P cases (49 breast cancer cases) and 212,795 person-years for 7935 female relatives (188 breast cancer cases), we found no increased breast cancer risk for either CL/P cases (hazard ratio [HR], 1.23; 95% confidence interval (CI), 0.92-1.63), mothers of children with CL/P (HR, 0.93; 95% CI, 0.80-1.08), or sisters of CL/P cases (HR, 0.94; 95% CI, 0.55-1.60), nor was there any significant differences in age of onset. CONCLUSION: Both epidemiological and genetic studies have suggested common etiological factors for breast cancer and CL/P. However, in this population-based study we were not able to confirm a general increase in the risk of breast cancer among female subjects in families with CL/P.