Publications of P Bata

Genetic and environmental influence on thyroid gland volume and thickness of thyroid isthmus: a twin study

OBJECTIVES: Decreased thyroid volume has been related to increased prevalence of thyroid cancer. SUBJECTS AND METHODS: One hundred and fourteen Hungarian adult twin pairs (69 monozygotic, 45 dizygotic) with or without known thyroid disorders underwent thyroid ultrasound. Thickness of the thyroid isthmus was measured at the thickest portion of the gland in the midline using electronic calipers at the time of scanning. Volume of the thyroid lobe was computed according to the following formula: thyroid height*width*depth*correction factor (0.63). RESULTS: Age-, sex-, body mass index- and smoking-adjusted heritability of the thickness of thyroid isthmus was 50% (95% confidence interval [CI], 35 to 66%). Neither left nor right thyroid volume showed additive genetic effects, but shared environments were 68% (95% CI, 48 to 80%) and 79% (95% CI, 72 to 87%), respectively. Magnitudes of monozygotic and dizygotic co-twin correlations were not substantially impacted by the correction of covariates of body mass index and smoking. Unshared environmental effects showed a moderate influence on dependent parameters (24-50%). CONCLUSIONS: Our analysis support that familial factors are important for thyroid measures in a general twin population. A larger sample size is needed to show whether this is because of common environmental (e.g. intrauterine effects, regional nutrition habits, iodine supply) or genetic effects.

Different genetic impact in the development of renal length and width: a twin study

Background Ultrasound measurements of renal dimensions are conventionally limited to renal length, shape and cortical thickness. These are regarded as adequate for normal therapeutic decision‐making and volume measurements are reserved for a few clinical trials. However, there is no evidence concerning the degree to which renal length or volume is independently susceptible to heritable and environmental influences. Aim We aimed to determine whether renal length or width (as a surrogate of volume) was more influenced by heritability. Methods A single operator measured renal length and width in 114 adult monozygotic and same‐sex dizygotic Hungarian twin pairs (mean age 43.6 ± 16.3 years), using an Esaote MyLab 70X ultrasound machine with curved array transducer (1–8 MHz, CA431). Results Analysis of within‐pair co‐twin correlations adjusted for age and gender showed that the age‐ and sex‐adjusted heritability of average renal length was 51% (95% confidence interval, 29–72%). Renal width showed negligible genetic influence. Common environmental effects had no influence, and unshared environments were responsible for 49–80% of the variance, mainly renal width. Conclusions This study is the first to demonstrate the moderate heritability and limited environmental influence on renal length, and the contrasting lack of heritability of renal width, which is mainly influenced by unshared environmental components, that is lifestyle habits. Renal width therefore better represents the influence of modifiable environmental factors than renal length. The results suggest that renal width not length should be reported to facilitate early detection and monitoring of renal disease.

Genetic and environmental variance of renal parenchymal thickness: a twin study

Aim: To estimate heritability and environmental effects on renal parenchymal thickness. Methods: In this twin study, renal parenchymal thickness of 98 Hungarian healthy adult twin pairs (68 monozygotic, 30 dizygotic) without kidney disease was measured bilaterally using renal ultrasound with Esaote MyLab 70X ultrasound machine with low-frequency curved transducers (1-8 MHz). Results: In both monozygotic and dizygotic group there were more women (76.5%). Mean right and left renal parenchymal thickness was 1.32 ± 0.33 cm and 1.62 ± 0.31 cm, respectively. Age-and sex-adjusted heritability of renal parenchymal thickness was 0.0% (95% confidence interval, 0.0 to 50.2%), shared and unshared environmental factor was 30.2% (4.1 to 55.9%) and 69.8% (45.8 to 89.5%), respectively. Conclusion: This study shows a negligible role of heritability and an important role of environmental effects in developing renal parenchymal thickness, emphasizing the importance of lifestyle for primary prevention.

Evidence for a strong genetic influence on carotid plaque characteristics: an international twin study

Background and Purpose— Few family studies reported moderate genetic impact on the presence and scores of carotid plaques. However, the heritability of carotid plaque characteristics remains still unclear. Twin studies more reliably estimate the relative contribution of genes to these traits in contrast to family study design. Methods— One hundred ninety-two monozygotic and 83 dizygotic adult twin pairs (age 49±15 years) from Italy, Hungary, and the United States underwent B-mode and color Doppler ultrasound of bilateral common, internal, and external carotid arteries. Results— Age-, sex-, and country-adjusted heritability was 78% for the presence of carotid plaque (95% CI, 55%–90%), 74% for plaque echogenicity (hypoechoic, hyperechoic, or mixed; 95% CI, 38%–87%), 69% for plaque size (area in mm2 in longitudinal plane; < or >50 percentile; 95% CI, 16%–86%), 74% for plaque sidedness (unilateral or bilateral; 95% CI, 25%–90%), 74% for plaque numerosity (95% CI, 26%–86%), 68% (95% CI, 40%–84%), and 66% (95% CI, 32%–90%) for the presence of plaque in carotid bulbs and proximal internal carotid arteries. No role of shared environmental factors was found. Unique environmental factors were responsible for the remaining variance (22%–34%). Controlling for relevant covariates did not change the results significantly. Conclusions— The heritability of ultrasound characteristics of carotid plaque is high. Unshared environmental effects account for a modest portion of the variance. Our findings should stimulate the search for genes responsible for these traits.

Heritability of non-alcoholic fatty liver disease and association with abnormal vascular parameters: A twin study

Background Non‐alcoholic fatty liver disease (NAFLD) has been linked to increased cardiovascular morbidity. However, genetic factors have an unclear role in this condition. Aims To analyse heritability of NAFLD and its association with abnormal vascular parameters in a large twin cohort. Methods Anthropometric and lipid metabolic parameters were obtained from 208 adult Hungarian twins (63 monozygotic and 41 dizygotic pairs; 58 men and 150 women; age 43.7 ± 16.7 years). B‐mode ultrasonography was performed to detect steatosis and categorize severity. Brachial and aortic augmentation indices and aortic pulse wave velocity were assessed using oscillometry (TensioMed Arteriograph). Carotid intima media thickness (IMT) was measured using ultrasonography on the proximal common, distal common and internal carotid arteries. Results NAFLD was identified in 47 subjects (22.6%), of which 44 (93.6%) had mild and 3 (6.4%) had moderate steatosis. These subjects were older (age: 50.9 ± 14.3 vs. 41.5 ± 16.7 years, P < 0.001) and had a higher body mass index (BMI; 30.1 ± 5.2 vs. 24.6 ± 4.1 km/m2, P < 0.001) than non‐NAFLD twins. Based on 91 same‐sex twin pairs, heritability analysis indicated no discernible role for genetic components in the presence of NAFLD (95% confidence interval, 0.0–36.0%), while shared and unshared environmental effects accounted for 74.2% and 25.8% of variations adjusted for age and BMI. Augmentation indices and carotid IMT in twins with NAFLD were increased at most examined locations (P < 0.05–P < 0.001). Conclusion These findings do not support heritability of NAFLD, although it coexists with vascular parameters linked to increased cardiovascular risk, underscoring the importance and value of prevention in this very common disorder.