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.


OBJECTIVE
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/m(2) , 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).


CONCLUSIONS
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.
Department of Radiology and Oncotherapy, Semmelweis University, Budapest, Hungary. tarnoki4@gmail.com
Adam D
AD
Tarnoki
David L
DL
Tarnoki
Pal
P
Bata
Levente
L
Littvay
Janos
J
Osztovits
Gyorgy
G
Jermendy
Kinga
K
Karlinger
Agnes
A
Lannert
Istvan
I
Preda
Robert G
RG
Kiss
Andrea A
AA
Molnar
Zsolt
Z
Garami
Gyorgy
G
Baffy
Viktor
V
Berczi
D000328:Adult; D000368:Aged; D001011:Aorta / Q000502:physiology; D001783:Blood Flow Velocity; D001916:Brachial Artery / Q000502:physiology; D018376:Cardiovascular Abnormalities / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000235:genetics*; D059168:Carotid Intima-Media Thickness; D003430:Cross-Sectional Studies; D005234:Fatty Liver / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D006801:Humans; D006814:Hungary / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009017:Morbidity; D065626:Non-alcoholic Fatty Liver Disease; D015995:Prevalence; D011673:Pulsatile Flow / Q000502:physiology; D012307:Risk Factors; D017539:Tunica Intima / Q000502:physiology; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D059289:Vascular Stiffness / Q000235:genetics