Genetic and Environmental Effects on Mortality Before Age 70 Years

Prevalence and mortality of COVID-19 are associated with the L55M functional polymorphism of Paraoxonase 1

Introduction

Accumulating evidence recommends that infectious diseases including coronavirus disease 2019 (COVID-19) are often associated with oxidative stress and inflammation. Paraoxonase 1 (PON1, OMIM: 168,820), a member of the paraoxonase gene family, has antioxidant properties. Enzyme activity of paraoxonase depends on a variety of influencing factors such as polymorphisms of PON1, ethnicity, gender, age, and a number of environmental variables. The PON1 has two common functional polymorphisms, namely, Q192R (rs662) and L55M (rs854560). The R192 and M55 alleles are associated with increase and decrease in enzyme activity, respectively.

Objective

The present study was conducted to investigate the possible association of rs662 and rs854560 polymorphisms with morbidity and mortality of COVID-19.

Methods

Data for the prevalence, mortality, and amount of accomplished diagnostic test (per 10⁶ people) on 25 November 2020 from 48 countries were included in the present study. The Human Development Index (HDI) was used as a potential confounding variable.

Results

The frequency of M55 was positively correlated with the prevalence (partial r = 0.487, df = 36, p = 0.002) and mortality of COVID-19 (partial r = 0.551, df = 36, p < 0.001), after adjustments for HDI and amount of the accomplished diagnostic test as possible confounders.

Conclusions

This means that countries with higher M55 frequency have higher prevalence and mortality of COVID-19.

Delayed age at transfer of adoptees to adoptive parents is associated with increased mortality irrespective of social class of the adoptive parents: a cohort study

BACKGROUND

Adverse early life experience and development may have long-term health consequences, but later environmental conditions may perhaps protect against the effects of such early life adversities. The aim was to investigate whether cause-specific and overall mortality rates among adoptees are associated with the age at which they were transferred to the adoptive family and whether the social class of the adoptive family modifies this association.

METHODS

A cohort of 10,592 non-familial adoptions (biologically unrelated adoptee and adoptive parents) of Danish-born children formally granted in 1924-47 and with follow-up of total and cause-specific mortality through ages up to 85 years. The rates of death after the age of 16 from all causes combined, all natural causes, all external causes, and suicide were compared according to the age at which adoptees were transferred to their adoptive family by estimating hazard ratios in Cox regression models.

RESULTS

Death rates from all causes were significantly higher in adoptees transferred between age 1 month and 4 years compared to those transferred immediately after birth with the hazard ratio peaking at 1.19 (95% confidence limit: 1.08 to 1.32) for adoptees transferred between 6 and 11 months. This result was primarily driven by a similar pattern for natural causes of death. For death from external causes and for suicide the hazard ratios were increasing with increasing age at transfer, and tests for trend were statistically significant. The social class of the adoptive family did not significantly modify these associations.

CONCLUSIONS

Transfer to an adoptive family later than at the time of birth may have adverse long-term consequences affecting overall and cause-specific mortality. These effects were not modified by the environment provided by the adoptive family as indicated by the social class of these families.

Genetic and familial environmental effects on suicide--an adoption study of siblings

BACKGROUND

While there is clear evidence of familial influences on suicide, the origin of these is less certain. We have investigated genetic and familial environmental factors by studying the occurrence of suicide in biological and adoptive siblings of adoptees who died by suicide compared to siblings of surviving adoptees.

METHOD

We used the Danish Adoption Register and Danish population registers to compare 221 siblings of adoptees who died by suicide with the siblings of 1,903 adoptees who did not die by suicide. All adoptions in the Danish Adoption Register are non-familial, i.e. the adoptive parents are biologically unrelated to the adoptee. Analyses were conducted on incidence rates of suicide in biological and adoptive siblings given occurrence of suicide in the adoptees while also taking into account psychiatric disorders.

RESULTS

The risk of suicide in full siblings of adoptees who died by suicide before age 60 years was significantly higher than in full siblings of adoptees who had not died by suicide (incidence rate ratios (IRR) = 5.01; 95% confidence interval [CI] = 1.28-19.6). This increase persisted after adjustment for history of psychiatric admission of siblings (IRR = 4.19; 95% CI = 1.00-17.5).

CONCLUSIONS

Genetic factors influence risk of suicide, probably independently of psychiatric disorder. This is relevant in provision of advice to families, including possible prevention of suicide.

Evaluation of demographic factors that influence acute radiation response

Casualty estimation tools are critical in planning for nuclear event scenarios. Current consequence assessment models based on healthy adult males may not adequately represent the population. To develop an understanding of the impact of demographic variables on casualty estimates, human data was surveyed to identify key demographic factors that affect acute radiation response. Information on in utero exposures, gender, age, and comorbidity status was collected from atomic bomb survivors, radiation accidents, and clinical oncology. Burn and trauma studies were also examined to gain insight into the impact of demographic variables on acute injury outcomes. Fetal radiation sensitivity is well documented; increased mortality or malformations are observed depending on gestational age. A greater incidence of radiation syndrome was observed among male atomic bomb survivors. Trauma data show increased mortality in males, apparently due to immunological differences between genders. Limited data suggest vulnerability in the very young and old due to immunological status and comorbidities, respectively. Certain genetically susceptible subpopulations demonstrate marked increased sensitivity to radiation exposure. Interaction of radiation and comorbid conditions has not been well studied; however, burn and trauma data indicate that comorbidities negatively impact response to acute injury. Key factors evaluated together with their prevalence indicate the importance of modeling demographic variability in casualty estimations. Also they can help identify vulnerable subpopulations and provide insight on treatment requirements.

Studies based on the Danish Adoption Register: schizophrenia, BMI, smoking, and mortality in perspective

INTRODUCTION

The genetic and familial environmental influences making up familial correlations in traits and familial aggregation of diseases may be disentangled by adoption studies. Thus, resemblance between the adoptee and the biological relatives indicates a contribution of the segregating gene they have in common, and resemblance between the adoptee and the rearing adoptive family members indicates influences of the shared family environment. The Danish Adoption Register includes information on all 14,425 non-familial adoptions of Danish children legally granted in Denmark from 1924 to 1947.

RESEARCH TOPICS

To illustrate the adoption study approach in research, we present results achieved in schizophrenia, body fatness, smoking, and mortality. Significantly higher prevalence of schizophrenia and related conditions were found in biological relatives to adoptees with schizophrenia than among biological relatives to adoptees without schizophrenia. Clear trends in body mass index of biological relatives and the weight of adoptees were found in several settings. A genetic influence on smoking habits were found within a generation. A moderate genetic influence on the mortality rate has been found.

CONCLUSION

The Danish Adoption Register has contributed to the knowledge about environmental and genetic influence in various fields. Genetic influence on the risk of schizophrenia, body fatness, smoking habits, and on the mortality rate has been found.

The Danish Adoption Register

INTRODUCTION

The Danish Adoption Register was established in 1963-1964 to explore the genetic and environmental contribution to familial aggregation of schizophrenia.

CONTENT

The register encompass information on all 14,425 non-familial adoptions of Danish children legally granted in Denmark 1924-1947. It includes name and date of birth of each adoptee and his or her biological and adoptive parents, date of transfer to adoptive parents and date of formal adoption.

VALIDITY AND COVERAGE

The linkage to biological and adoptive parents is close to complete, even biological fathers are registered for 91.4% of the adoptees.

CONCLUSION

Adoption registers are a unique source allowing disentangling of genetic and familial environmental influences on traits, risk of diseases, and mortality.

Excess mortality rate during adulthood among Danish adoptees

BACKGROUND AND OBJECTIVE

Adoption studies have been used to disentangle the influence of genes from shared familial environment on various traits and disease risks. However, both the factors leading to adoption and living as an adoptee may bias the studies with regard to the relative influence of genes and environment compared to the general population. The aim was to investigate whether the cohort of domestic adoptees used for these studies in Denmark is similar to the general population with respect to all-cause mortality and cause-specific mortality rates.

METHODS

13,111 adoptees born in Denmark in 1917, or later, and adopted in 1924 to 1947 were compared to all Danes from the same birth cohorts using standardized mortality ratios (SMR). The 12,729 adoptees alive in 1970 were similarly compared to all Danes using SMR as well as cause-specific SMR.

RESULTS

The excess in all-cause mortality before age 65 years in adoptees was estimated to be 1.30 (95% CI 1.26-1.35). Significant excess mortality before age 65 years was also observed for infections, vascular deaths, cancer, alcohol-related deaths and suicide. Analyses including deaths after age 65 generally showed slightly less excess in mortality, but the excess was significant for all-cause mortality, cancer, alcohol-related deaths and suicides.

CONCLUSION

Adoptees have an increased all-cause mortality compared to the general population. All major specific causes of death contributed, and the highest excess is seen for alcohol-related deaths.

Genetic influences on incidence and case-fatality of infectious disease

Background

Family, twin and adoption studies suggest that genetic susceptibility contributes to familial aggregation of infectious diseases or to death from infections. We estimated genetic and shared environmental influences separately on the risk of acquiring an infection (incidence) and on dying from it (case fatality).

Methods

Genetic influences were estimated by the association between rates of hospitalization for infections and between case-fatality rates of adoptees and their biological full- and half- siblings. Familial environmental influences were investigated in adoptees and their adoptive siblings. Among 14,425 non-familial adoptions, granted in Denmark during the period 1924–47, we selected 1,603 adoptees, who had been hospitalized for infections and/or died with infection between 1977 and 1993. Their siblings were considered predisposed to infection, and compared with non-predisposed siblings of randomly selected 1,348 adoptees alive in 1993 and not hospitalized for infections in the observation period. The risk ratios presented were based on a Cox regression model.

Results

Among 9971 identified siblings, 2829 had been hospitalised for infections. The risk of infectious disease was increased among predisposed compared with non-predisposed in both biological (1.18; 95% confidence limits 1.03–1.36) and adoptive siblings (1.23; 0.98–1.53). The risk of a fatal outcome of the infections was strongly increased (9.36; 2.94–29.8) in biological full siblings, but such associations were not observed for the biological half siblings or for the adoptive siblings.

Conclusion

Risk of getting infections appears to be weakly influenced by both genetically determined susceptibility to infection and by family environment, whereas there appears to be a strong non-additive genetic influence on risk of fatal outcome.

Genetic and environmental influences on risk of death due to infections assessed in Danish twins, 1943-2001

Genetic differences have been proposed to play a strong role in risk of death from infectious diseases. The study base of 44,005 included all same-sex twin pairs born in 1870-2001, with both twins alive on January 1, 1943, or those born thereafter. Cause of death was obtained from the Danish Cause of Death Register and was available for 18,359 deaths. The authors classified death due to infections by 3 definitions (narrow, broader, and broadest) and calculated concordance rates for same-sex monozygotic and dizygotic twin pairs. Heritability was estimated by using structural equation models. When the 3 definitions were applied, 211 (1.1%), 1,089 (5.9%), and 2,907 (15.8%) deaths, respectively, were due to infections. The probandwise concordance rates for monozygotic twin pairs were consistently higher than for dizygotic twin pairs regardless of the definition (9% vs. 0% (P = 0.04), 10% vs. 3% (P < 0.01), and 19% vs. 15% (P = 0.07), respectively). For the broader and broadest definitions, heritability was 40% (95% confidence interval: 12, 50) and 19% (95% confidence interval: 3, 35), respectively. The concordance rates were generally low, and, although a genetic influence on the risk of death from infectious diseases could be demonstrated, the absolute effect of the genetic component on mortality was small.