Family and twin studies in inflammatory bowel disease

Studies examining the inheritance of inflammatory bowel disease （IBD） within different family groups have been the basis for recent molecular advances in the genetics of IBD. The derived heritability in Crohn＇s disease （CD） is higher than in many other complex diseases. The risk of IBD is highest in first-degree relatives of a CD proband, but first-degree relatives of a proband suffering from ulcerative colitis （UC） and more distant relatives are also at increased risk. Disease concordance rates in IBD have been examined in multiplex families and in three large European twin studies.

Genetic determination of irritable bowel syndrome

Irritable bowel syndrome （IBS） is a common functional gastrointestinal disorder. According to the Rome m criteria, IBS is defined as recurrent abdominal pain or discomfort for at least 3 d per month during the previous 3 mo associated with two or more of the following symptoms： improvement with defecation, onset associated with a change in the frequency of stool and/or onset associated with a change in form or appearance of stool. There is growing evidence regarding the genetic contribution in IBS, however the precise etiology of IBS is still unknown. The evaluation of the genetic influence is based on twin studies, familial aggregation and genetic epidemiological investigations. Most studies showed a concordance for IBS significantly greater in monozygotic than in dizygotic twins. The majority of the studies have shown that familial aggregation may represent exposures to a similar environment, as well as the influence of genetic factors. Whereas no specific gene has been identified in association with IBS, recent studies have noticed the importance of polymorphisms in the promoter region of the serotonin reuptake transporter gene, G-protein beta 3 subunit gene （C825T）, cholecystokinin receptor （CCKAR gene 779T〉C）, and high-producer tumor necrosis factor genotype. Further studies are necessary to determine how genetic factors influence the clinical manifestations and therapeutical response in IBS patients.

Current understandings of the pathogenesis of type 1 diabetes:Genetics to environment

Type 1 diabetes(T1D)is an autoimmune disease that usually strikes early in life,but can affect individuals at almost any age.It is caused by autoreactive T cells that destroy insulin-producing beta cells in the pancreas.Epidemiological studies estimate a prevalence of 1 in 300 children in the United States with an increasing incidence of 2%-5%annually worldwide.The daily responsibility,clinical management,and vigilance required to maintain blood sugar levels within normal range and avoid acute complications(hypoglycemic episodes and diabetic ketoacidosis)and long term micro-and macro-vascular complications significantly affects quality of life and public health care costs.Given the expansive impact of T1D,research work has accelerated and T1D has been intensively investigated with the focus to better understand,manage and cure this condition.Many advances have been made in the past decades in this regard,but key questions remain as to why certain people develop T1D,but not others,with the glaring example of discordant disease incidence among monozygotic twins.In this review,we discuss the field’s current understanding of its pathophysiology and the role of genetics and environment on the development of T1D.We examine the potential implications of these findings with an emphasis on T1D inheritance patterns,twin studies,and disease prevention.Through a better understanding of this process,interventions can be developed to prevent or halt it at early stages.

Gut Microbiota Diversity and Overweight/Obesity in Infancy:Results from a Nested Case-control Study

Objective:Childhood obesity is a major health concern worldwide.Previous studies have explored the relationship between obesity and gut microbiota.However,the results from such studies remain contradictory.Methods:In the present nested case-control study,based on a twin birth cohort study,the relationship between gut microbiota diversity and overweight/obesity in 1-and 6-month-old infants was explored.

Effects of asthma on stability of Wisconsin card sorting test measures A twin study

BACKGROUND： The four measures used to assess the stability of the Wisconsin card sorting test （WCST）, that is, the number of preservative errors, percentage of preservative errors, number of categories completed, and the number of trials to complete the first category, reflect the function of the frontal lobe. OBJECTIVE： This study was designed to investigate the effects of asthma on the stability of WCST measurements through the use of a twin study, and to analyze whether egg-type difference exists. DESIGN： A cohort study. SETTING： Mental Health Center, the First Affiliated Hospital of Chongqing Medical University. PARTICIPANTS： Fifty-nine pairs of twins, aged 6-16 years, were primarily selected from schools between August 2005 and February 2007 and the WCST and Zygosity identification test was applied. Twins with achromatopsia, severe upper limb diseases, somatic diseases, or mental disorders were excluded. According to disease history of asthmatic attack, children were assigned into asthma （n = 16） and non-asthma （n = 43） groups. METHODS： Four WCST measurements were determined in the 59 pairs of twins, and egg-type differences were identified in conjunction. RESULTS： All 59 pairs of twins were included in the final analysis. Among the pairs of twins, 28 （48.5 %） were monozygotic twins, and 31 （52%） were dizygotic twins. Among the monozygotic and dizygotic twins, the number of preservative errors and percentage of preservative errors were significantly higher in the asthma group than in the non-asthma group （P 〈 0.05）. However, there was no significant difference of each corresponding measure between the monozygotic and dizygotic twins （P 〉 0.05）. CONCLUSION： Asthma may affect the stability of WCST measures, but egg-type differences do not exist.

An update of the Guangzhou Twin Eye Study

The Guangzhou Twin Eye Study(GTES)is a population-based study of young twins residing in Guangzhou City.The major aim of GTES is to explore the impact of genes,environmental factors and gene-environment interactions on common eye diseases.From 2006,for more than 1,300 twin pairs,age 7-26 years old,progressive ocular phenotypes,such as refraction,ocular biometrics,weight,and height were collected annually,while non-progressive phenotypes such as parental refraction,corneal thickness,retinal fundus,intraocular pressure and DNA only collected at baseline.In the current study,we summarize the major findings on the etiology of myopia in recent decades.

Translating current biomedical therapies for long duration,deep space missions

It is been shown that spaceflight-induced molecular,cellular,and physiologic changes cause alterations across many modalities of the human body,including cardiovascular,musculoskeletal,hematological,immunological,ocular,and neurological systems.The Twin Study,a multi-year,multi-omic study of human response to spaceflight,provided detailed and comprehensive molecular and cellular maps of the human response to radiation,microgravity,isolation,and stress.These rich data identified epigenetic,gene expression,inflammatory,and metabolic responses to spaceflight,facilitating a better biomedical roadmap of features that should be monitored and safe-guarded in upcoming missions.Further,by exploring new developments in pre-clinical models and clinical trials,we can begin to design potential cellular interventions for exploration-class missions to Mars and potentially farther.This paper will discuss the overall risks astronauts face during spaceflight,what is currently known about human response to these risks,what pharmaceutical interventions exist for use in space,and which tools of precision medicine and cellular engineering could be applied to aerospace and astronaut medicine.

Genetic effects on serum testosterone and sex hormone-binding globulin in men： a Korean twin and family study

We conducted a community-based cross-sectional study to evaluate the role of genetics in determining the individual difference in total testosterone and sex hormone-binding globulin levels. Study participants comprised 730 Korean men consisting of 142 pairs of monozygotic twins, 191 pairs of siblings, and 259 father-offspring pairs from 270 families who participated in the Healthy Twin study. Serum concentration of total testosterone and sex hormone-binding globulin were measured by chemiluminescence immunoassay, and free testosterone and bioavailable testosterone were calculated using Vermeulen＇s method. Quantitative genetic analysis based on a variance decomposition model showed that the heritability of total testosterone, free testosterone, bioavailable testosterone, and sex hormone-binding globulin were 0.56, 0.45, 0.44, and 0.69, respectively after accounting for age and body mass index. Proportions of variance explained by age and body mass index varied across different traits, from 8% for total testosterone to 31% for sex hormone-binding globulin. Bivariate analysis showed a high degree of additive genetic correlation （p~ = 0.67） and a moderate degree of individual-specific environmental correlation （PE = 0.42） between total testosterone and sex hormone-binding globulin. The findings confirmed the important role of genetics in determining the individually different levels of testosterone and sex hormone-binding globulin during adulthood in Korean men as found in non-Asian populations, which may suggest that common biologic control for determining testosterone level directly or indirectly through binding protein are largely shared among different populations.