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A special issue of Medicina (ISSN 1648-9144). This special issue belongs to the section "Genetics and Molecular Medicine".

Deadline for manuscript submissions: closed (1 January 2021) | Viewed by 23266

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Dr. Adam Domonkos Tarnoki

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Guest Editor

Medical Imaging Centre, Semmelweis University, Budapest, Hungary
Interests: genetics; epigenetics; microbiome; imaging; cardiovascular diseases
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Dr. David Laszlo Tarnoki

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Guest Editor

Medical Imaging Centre, Semmelweis University, Budapest, Hungary
Interests: genetics; epigenetics; microbiome; imaging; respiratory diseases
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Special Issue Information

Dear Colleagues,

Medicina is planning a Special Issue in 2020 to collect original manuscripts on recent findings in twin research. Twin studies continue to be an important study design to understand various aspects of human genetics along with genome and molecular research methods and on how environmental factors and genetics contribute to various traits. Today, the role of epigenetic and microbiome studies involving disease-discordant monozygotic twins is emerging to study epigenetic variation as a dynamic quantitative trait. Therefore, this Special Issue will summarize the latest, most interesting results of twin studies in various fields, which will be published in December 2020, and we encourage you to submit your manuscripts by 31 October 2020. For all technical details, please see the instructions to authors on the website of the publisher, MDPI (https://www.mdpi.com/journal/medicina/instructions).

Thank you in advance, and we look forward to receiving your manuscript.

Dr. Adam Domonkos Tarnoki
Dr. David Laszlo Tarnoki
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Medicina is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Human genetics
Environment
Epigenetics
Microbiome
Psychology
Heritability
Personalized medicine
Imaging

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Published Papers (8 papers)

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10 pages, 480 KiB

Open AccessArticle

Left Ventricular Systolic Function Has Strong Independent Genetic Background from Diastolic Function: A Classical Twin Study

by Andrea Ágnes Molnár, Márton Kolossváry, Bálint Lakatos, Márton Tokodi, Ádám Domonkos Tárnoki, Dávid László Tárnoki, Attila Kovács, Bálint Szilveszter, Szilard Voros, György Jermendy, Pál Maurovich-Horvat and Béla Merkely

Medicina 2021, 57(9), 935; https://doi.org/10.3390/medicina57090935 - 5 Sep 2021

Cited by 1 | Viewed by 1771

Abstract

Background and Objectives: No data are available on whether the heritability of left ventricle (LV) systolic and diastolic parameters are independent of each other. Therefore, our aim was to assess the magnitude of common and independent genetic and environmental factors defining LV systolic and diastolic function. Materials and Methods: We analyzed 184 asymptomatic twins (65% female, mean age: 56 ± 9 years). Transthoracic echocardiography was performed to measure LV systolic (global longitudinal and circumferential strain; basal and apical rotation) and diastolic (early diastolic velocity of mitral inflow and lateral mitral annulus tissue; deceleration time and early diastolic strain rate) parameters using conventional and speckle-tracking echocardiography. Genetic structural equation models were evaluated to quantify the proportion of common and specific genetic (Ac, As) and environmental factors (Ec, Es) contributing to the phenotypes. Results: LV systolic parameters had no common genetic or environmental heritability (Ac range: 0–0%; Ec range: 0–0%; As range: 57–77%; Es range: 24–43%). Diastolic LV parameters were mainly determined by common genetic and environmental effects (Ac range: 9–40%; Ec range: 11–49%; As range: 0–29%; Es range: 0–51%). Systolic parameters had no common genetic or environmental factors (Ac = 0%; Ec = 0%) with diastolic metrics. Conclusions: Systolic LV parameters have a strong genetic predisposition to any impact. They share no common genetic or environmental factors with each other or with diastolic parameters, indicating that they may deteriorate specifically to given effects. However, diastolic functional parameters are mainly affected by common environmental influences, suggesting that pathological conditions may deteriorate them equally. Estimation of the genetic and environmental influence and interdependence on systolic and diastolic LV function may help the understanding of the pathomechanism of different heart failure classification types. Full article

(This article belongs to the Special Issue A Focus on Twin Studies)

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12 pages, 976 KiB

Open AccessArticle

Genetic and Environmental Structure of Altruism Characterized by Recipients in Relation to Personality

by Juko Ando and Tetsuya Kawamoto

Medicina 2021, 57(6), 593; https://doi.org/10.3390/medicina57060593 - 8 Jun 2021

Cited by 2 | Viewed by 3279

Abstract

Background and Objectives: Altruism is a form of prosocial behavior with the goal of increasing the fitness of another individual as a recipient while reducing the fitness of the actor. Although there are many studies on its heterogeneity, only a few behavioral genetic studies have been conducted to examine different recipient types: family members favored by kin selection, the dynamic network of friends and acquaintances as direct reciprocity, and strangers as indirect reciprocity. Materials and Methods: This study investigated the genetic and environmental structure of altruism with reference to recipient types measured by the self-report altruism scale distinguished by the recipient (the SRAS-DR) and examine the relationship to personality dimensions measured by the NEO-FFI with a sample of 461 adult Japanese twin pairs. Results: The present study shows that there is a single common factor of altruism: additive genetic effects explain 51% of altruism without a shared environmental contribution. The genetic contribution of this single common factor is explained by the genetic factors of neuroticism (N), extraversion (E), openness to experience (O), and conscientiousness (C), as well as a common genetic factor specific to altruism. Only altruism toward strangers is affected by shared environmental factors. Conclusions: Different types of altruistic personality are constructed by specific combinational profiles of general personality traits such as the Big Five as well as a genetic factor specific to altruism in each specific way. Full article

(This article belongs to the Special Issue A Focus on Twin Studies)

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12 pages, 1384 KiB

Open AccessArticle

Heritability of Cardiothoracic Ratio and Aortic Arch Calcification in Twins

by Zsofia Jokkel, Bianka Forgo, Christopher Hani-Gaius Ghattas, Marton Piroska, Helga Szabó, David L. Tarnoki, Adam D. Tarnoki, Sooji Lee and Joohon Sung

Medicina 2021, 57(5), 421; https://doi.org/10.3390/medicina57050421 - 27 Apr 2021

Cited by 1 | Viewed by 2837

Abstract

Background and Objectives: Aortic arch calcification (AoAC) is associated with a variety of cardiovascular complications. The measurement and grading of AoAC using posteroanterior (PA) chest X-rays are well established. The cardiothoracic ratio (CTR) can be simultaneously measured with PA chest X-rays and used as an index of cardiomegaly. The genetic and environmental contributions to the degree of the AoAC and CTR are not well understood. The purpose of this study was to investigate the effect of genetics and environmental factors on the AoAC and CTR. Materials and Methods: A total of 684 twins from the South Korean twin registry (261 monozygotic, MZ and 81 dizygotic, DZ pairs; mean age 38.6 ± 7.9 years, male/female = 264/420) underwent PA chest X-rays. Cardiovascular risk factors and anthropometric data were also collected. The AoAC and CTR were measured and graded using a standardized method. A structural equation method was used to calculate the proportion of variance explained by genetic and environmental factors behind AoAC and CTR. Results: The within-pair differences were low regarding the grade of AoAC, with only a few twin pairs showing large intra-pair differences. We found that the thoracic width showed high heritability (0.67, 95% CI: 0.59–0.73, p = 1). Moderate heritability was detected regarding cardiac width (0.54, 95% CI: 0.45–0.62, p = 0.572) and CTR (0.54, 95% CI: 0.44–0.62, p = 0.701). Conclusions: The heritable component was significant regarding thoracic width, cardiac width, and the CTR. Full article

(This article belongs to the Special Issue A Focus on Twin Studies)

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13 pages, 1150 KiB

Open AccessArticle

Relationship between Nutrient Intake and Human Gut Microbiota in Monozygotic Twins

by Natsuko Matsumoto, Jonguk Park, Rie Tomizawa, Hitoshi Kawashima, Koji Hosomi, Kenji Mizuguchi, Chika Honda, Ritsuko Ozaki, Yoshinori Iwatani, Mikio Watanabe and Jun Kunisawa

Medicina 2021, 57(3), 275; https://doi.org/10.3390/medicina57030275 - 16 Mar 2021

Cited by 9 | Viewed by 4081

Abstract

Background and Objectives: The gut microbiota is associated with human health and dietary nutrition. Various studies have been reported in this regard, but it is difficult to clearly analyze human gut microbiota as individual differences are significant. The causes of these individual differences in intestinal microflora are genetic and/or environmental. In this study, we focused on differences between identical twins in Japan to clarify the effects of nutrients consumed on the entire gut microbiome, while excluding genetic differences. Materials and Methods: We selected healthy Japanese monozygotic twins for the study and confirmed their zygosity by matching 15 short tandem repeat loci. Their fecal samples were subjected to 16S rRNA sequencing and bioinformatics analyses to identify and compare the fluctuations in intestinal bacteria. Results: We identified 12 genera sensitive to environmental factors, and found that Lactobacillus was relatively unaffected by environmental factors. Moreover, we identified protein, fat, and some nutrient intake that can affect 12 genera, which have been identified to be more sensitive to environmental factors. Among the 12 genera, Bacteroides had a positive correlation with retinol equivalent intake (rs = 0.38), Lachnospira had a significantly negative correlation with protein, sodium, iron, vitamin D, vitamin B6, and vitamin B12 intake (rs = −0.38, −0.41, −0.39, −0.63, −0.42, −0.49, respectively), Lachnospiraceae ND3007 group had a positive correlation with fat intake (rs = 0.39), and Lachnospiraceae UCG-008 group had a negative correlation with the saturated fatty acid intake (rs = −0.45). Conclusions: Our study is the first to focus on the relationship between human gut microbiota and nutrient intake using samples from Japanese twins to exclude the effects of genetic factors. These findings will broaden our understanding of the more intuitive relationship between nutrient intake and the gut microbiota and can be a useful basis for finding useful biomarkers that contribute to human health. Full article

(This article belongs to the Special Issue A Focus on Twin Studies)

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18 pages, 667 KiB

Open AccessArticle

Overlapping Genetic Background of Coronary Artery and Carotid/Femoral Atherosclerotic Calcification

by Anita Hernyes, Marton Piroska, Bence Fejer, Laszlo Szalontai, Helga Szabo, Bianka Forgo, Adam L. Jermendy, Andrea A. Molnar, Pal Maurovich-Horvat, Gyorgy Jermendy, Bela Merkely, David L. Tarnoki and Adam D. Tarnoki

Medicina 2021, 57(3), 252; https://doi.org/10.3390/medicina57030252 - 9 Mar 2021

Cited by 2 | Viewed by 2747

Abstract

Background and objectives: Multivessel atherosclerosis and its genetic background are under-investigated, although atherosclerosis is seldom local and still causes high mortality. Alternative methods to assess coronary calcification (CAC) might incorporate genetic links between different arteries’ atherosclerotic involvement, however, co-occurrences of coronary calcification have not been investigated in twins yet. Materials and Methods: We assessed the heritability of radio morphologically distinct atherosclerotic plaque types in coronary (non-enhanced CT, Agatston score), carotid, and femoral arteries (B-mode ultrasound) in 190 twin subjects (60 monozygotic, 35 dizygotic pairs). Four-segment scores were derived in order to assess the dissemination of the distinct plaque types in the carotid and femoral arteries taking bilaterality into account. We calculated the genetic correlation between phenotypically correlating plaque types in these arteries. Results: CAC and dissemination of calcified plaques in the carotid and femoral arteries (4S_hyper) were moderately heritable (0.67 [95% CI: 0.37–1] and 0.69 [95% CI: 0.38–1], respectively) when adjusted for age and sex. Hypoechoic plaques in the carotid and femoral arteries showed no heritability, while mixed plaques showed intermediate heritability (0.50 [95% CI: 0–0.76]). Age and sex-adjusted phenotypic correlation between CAC and 4segm_hyper was 0.48 [95% CI: 0.30–0.63] and the underlying genetic correlation was 0.86 [95% CI: 0.42–1]. Conclusions: Calcification of atherosclerotic plaques is moderately heritable in all investigated arteries and significant overlapping genetic factors can be attributed to the phenotypical resemblance of coronary and carotid or femoral atherosclerotic calcification. Our findings support the idea of screening extracoronary arteries in asymptomatic individuals. We also propose a hypothesis about primarily carotid-coronary and femoral-coronary atherosclerosis as two distinct genetic predispositions to co-localization. Full article

(This article belongs to the Special Issue A Focus on Twin Studies)

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9 pages, 1343 KiB

Open AccessArticle

Strong Genetic Effects on Bone Mineral Density in Multiple Locations with Two Different Techniques: Results from a Cross-Sectional Twin Study

by Marton Piroska, David Laszlo Tarnoki, Helga Szabo, Zsofia Jokkel, Szilvia Meszaros, Csaba Horvath and Adam Domonkos Tarnoki

Medicina 2021, 57(3), 248; https://doi.org/10.3390/medicina57030248 - 8 Mar 2021

Cited by 12 | Viewed by 2139

Abstract

Background and Objectives: Previous studies have demonstrated that risk of hip fracture is at least partly heritable. The aim of this study was to determine the magnitude of the genetic component of bone mineral density (BMD), using both X-ray and ultrasound assessment at multiple sites. Materials and Methods: 216 adult, healthy Hungarian twins (124 monozygotic, MZ, 92 dizygotic, DZ; mean age 54.2 ± 14.3 years), recruited from the Hungarian Twin Registry with no history of oncologic disease underwent cross-sectional BMD studies. We measured BMD, T- and Z-scores with dual energy X-ray absorptiometry (DEXA) at multiple sites (lumbar spine, femoral neck, total hip and radius). Quantitative bone ultrasound (QUS) was also performed, resulting in a calculated value of estimated bone mineral density (eBMD) in the heel bone. Heritability was calculated using the univariate ACE model. Results: Bone density had a strong genetic component at all sites with estimates of heritability ranging from 0.613 to 0.838 in the total sample. Lumbar BMD and calcaneus eBMD had major genetic components with estimates of 0.828 and 0.838 respectively, and least heritable (0.653) at the total hip. BMD of the radius had also a strong genetic component with an estimate of 0.806. No common environmental effect was found. The remaining variance was influenced by unique environment (0.162 to 0.387). In females only, slightly higher additive genetic estimates were found, especially in the case of the femoral neck and total hip. Conclusion: Bone mineral density is strongly heritable, especially in females at all locations using both DEXA and QUS, which may explain the importance of family history as a risk factor for bone fractures. Unshared environmental effects account for the rest of the variance with slight differences in magnitude across various bone regions, supporting the role of lifestyle in preventing osteoporotic fractures with various efficacy in different bone regions. Full article

(This article belongs to the Special Issue A Focus on Twin Studies)

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11 pages, 1040 KiB

Open AccessArticle

Association between Gut Microbial Diversity and Carotid Intima-Media Thickness

by Helga Szabo, Anita Hernyes, Marton Piroska, Balazs Ligeti, Peter Fussy, Luca Zoldi, Szonja Galyasz, Nora Makra, Dora Szabo, Adam Domonkos Tarnoki and David Laszlo Tarnoki

Medicina 2021, 57(3), 195; https://doi.org/10.3390/medicina57030195 - 25 Feb 2021

Cited by 18 | Viewed by 2657

Abstract

Background and Objectives: There is an increasing focus on the effect of the gut microbiome on developing atherosclerosis, but there is still no unified standpoint. We aimed to find associations between intestinal microbiome diversity and a marker of subclinical atherosclerosis, the carotid intima-media thickness (IMT). Materials and Methods: Recruited from the Hungarian Twin Registry, 108 monozygotic (MZ) twins (mean age 52.4 ± 14.1 years, 58% female) underwent a comprehensive carotid ultrasound examination (Samsung RS85). Of the 108 MZ twins, 14 pairs (mean age 65 ± 6.4 years, 71% female) discordant for carotid IMT were selected to undergo a stool sample collection. A special stool sampling container was mailed and received from each participant. After DNA extraction, library construction was performed specifically for the V3–V4 hypervariable region of microbial 16S rRNA. Next, the microbiome composition of the samples was determined using Kraken software. Two hypotheses were tested with the exact permutation test: (1) in the group with normal IMT, the Shannon index of the phyla is higher; and (2) the Firmicutes/Bacteroidetes ratio is greater in the group with high IMT values. Furthermore, the abundance of different bacterial strains present at higher and normal IMT was also explored. Statistical analysis was carried out using R software. Results: Increased Firmicutes/Bacteroidetes ratio was associated with increased IMT (mean Firmicutes/Bacteroidetes ratio of IMT > 0.9 and IMT < 0.9 groups: 2.299 and 1.436, respectively; p = 0.031). In the group with normal IMT values, a substantially higher fraction of Prevotellaceae was observed in contrast with subjects having subclinical atherosclerosis. However, there was no significant difference in the alpha diversity between the two groups. Conclusions: The determining role of individual genera and their proportions in the development and progression of atherosclerosis can be assumed. Further studies are needed to clarify if these findings can be used as potential therapeutic targets. Full article

(This article belongs to the Special Issue A Focus on Twin Studies)

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10 pages, 1269 KiB

Open AccessArticle

Are the Morphological Indices of the Vertebrobasilar System Heritable? A Twin Study Based on 3D Reconstructed Models

by Laszlo Szalontai, Zsofia Jokkel, Tamas Horvath, Marton Piroska, Bianka Forgo, Csaba Olah, Laszlo Kostyal, David L. Tarnoki and Adam D. Tarnoki

Medicina 2021, 57(2), 127; https://doi.org/10.3390/medicina57020127 - 1 Feb 2021

Cited by 4 | Viewed by 2710

Abstract

Background and Objectives: The asymmetrical vertebral artery (VA) flow and diameter are common findings, which can result in an asymmetrical blood flow in the basilar artery (BA), leading to bending of the artery over time. This study investigated whether the variation of the different vertebrobasilar morphological indices that influence flow characteristics might be inherited. Materials and Methods: We analyzed 200 cerebral magnetic resonance imaging (MRI) scans of healthy Caucasian twins (100 pairs) who underwent time-of-flight MRI. From the scans, we reconstructed the 3D mesh of the posterior circulation from the start of the V4 segment to the basilar tip and subsequently analyzed the morphology of the vertebrobasilar system. The phenotypic covariances of the different morphological parameters were decomposed into heritability (A), shared (C), and unshared (E) environmental effects. Results: 39% of the twins had left dominant VA, while 32.5% had right dominant. In addition, 28.5% were classified as equal. The vertebral artery V4 segment diameter, curvature, and tortuosity were mainly influenced by shared (C) and unshared (E) environmental factors. A moderate heritability was found for the BA length (A: 63%; 95% CI: 45.7–75.2%; E: 37%; 95% CI: 24.8–54.3%) and volume (A: 60.1%; 95% CI: 42.4–73.2%; E: 39.9%; 95% CI: 26.8–57.6%), while the torsion of both arteries showed no heritability and were only influenced by the unshared environment. Conclusions: The length and volume of the BA show a moderate genetical influence. However, most of the measured morphological indices were influenced by shared and unshared factors, which highlight the role of the ever-changing hemodynamic influences shaping the geometry of the vertebrobasilar system. Full article

(This article belongs to the Special Issue A Focus on Twin Studies)

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