Search results for "Monozygotic"
showing 10 items of 123 documents
Genetic influences on resting electrocardiographic variables in older women: a twin study.
2009
Background: Previous studies in young and middle-aged men and women have shown that resting electrocardiographic (ECG) variables are influenced by genetic factors. However, the extent to which resting ECG variables are influenced by genetic factors in older women is unknown. Thus, the aim of this study was to estimate the relative contribution of genetic and environmental influences to individual differences in resting ECG variables among older female twins without overt cardiac diseases. Methods: Resting ECG recordings were obtained from 186 monozygotic and 203 dizygotic twin individuals, aged 63–76 years. Quantitative genetic modeling was used to decompose the phenotypic variance in each …
Heritability of maximal isometric muscle strength in older female twins.
2003
The purpose of the present study was to examine genetic and environmental effects on maximal isometric handgrip, knee extension, and ankle plantar flexion strength. In addition, we wanted to investigate whether the strength of these three muscle groups shares a genetic component or whether the genetic effect is specific for each muscle group. Muscle strength was measured as part of the Finnish Twin Study on Aging in 97 monozygotic (MZ) and 102 dizygotic (DZ) female twin pairs, aged 63-76 yr. The MZ and DZ individuals did not differ from each other in age, body height, weight, or self-related health. The age-adjusted pairwise (intraclass) correlations of the MZ and DZ twins were, respective…
Heredity of interocular similarities in components of refraction: a population-based twin study among 66- to 79-year-old female twins.
2019
Purpose: To examine genetic influences on interocular similarities in ocular refraction and components of refraction among elderly female twins. Methods: Refraction was assessed in 94 monozygotic (MZ) and 74 dizygotic (DZ) female twins aged 66–78 years. Absolute values of interocular differences (Aniso variables) in spherical refraction (SR), refractive astigmatism (AST), spherical equivalent (SE), corneal refractive power (CR), corneal astigmatism (CAST), anterior chamber depth (ACD) and axial length (AL) were calculated. The differences between sisters in each of the Aniso variables were calculated and graded into two categories, best differentiating the groups, here isometropic and aniso…
Aging and systemic hormonal status affects the circulating miR-21, miR-146a and FasL levels
2015
MicroRNAs are small molecules, found in all cell types and body fluids, which most commonly affect negatively to gene expressions by translational repression. Their role in various physiological conditions and diseases has been emphasized during the last twenty years. In our recent studies with postmenopausal monozygotic twin sisters (n=11), we have investigated how different systemic hormonal status affects the levels of specific circulating microRNAs and other molecules related to inflammation and apoptosis, both processes associated with aging. Our results have shown that the systemic levels of miR-21, miR-146a and Fas ligand are lower within the postmenopausal women who are using estrog…
Heritability of corneal refraction and corneal astigmatism: a population-based twin study among 66- to 79-year-old female twins.
2012
. Purpose: To examine the heritability of corneal refraction power (CR) and corneal astigmatism (AST) in older women. Methods: Corneal refraction and AST were measured by IOL master in 52 monozygotic (MZ) and 47 dizygotic (DZ) female twin pairs aged 66–79 years. The relative contribution of genetic and environmental factors to individual differences in CR was estimated by applying an independent pathway model to the twin data and AST by intraclass correlations (ICC). Results: For the right eye, mean CR was 44.58 dioptres (D) (standard deviation (SD) ±1.28) When comparing CR of the right and left eye between MZ and DZ, no significant difference was found. Mean AST was 0.77 D (SD ±0.44) wi…
Leisure-time physical activity and intra-abdominal fat in young adulthood: A monozygotic co-twin control study
2016
Objective To investigate differences in abdominal fat compartments between young adult monozygotic twin pairs discordant for leisure-time physical activity. Methods Ten young adult male monozygotic twin pairs (age range 32-36 years) discordant for leisure-time physical activity during the past 3 years were systematically selected from a population-based Finnish twin cohort. Magnetic resonance image at the level of the L2-L3 intervertebral disc was used to predict intra-abdominal and subcutaneous abdominal fat masses. Dietary intake was assessed with a 4-day food diary. Results Inactive twins had 31% more intra-abdominal fat than their active co-twins (mean difference 0.52 kg, 95% CI 0.12 to…
Combination of hormone replacement therapy and high physical activity is associated with differences in Achilles tendon size in monozygotic female tw…
2009
Estrogen concentration has been suggested to play a role in tendon abnormalities and injury. In physically active postmenopausal women, hormone replacement therapy (HRT) has been suggested to decrease tendon diameter. We hypothesized that HRT use and physical activity are associated with Achilles tendon size and tissue structure. The study applied cotwin analysis of fourteen 54- to 62-yr-old identical female twin pairs with current discordance for HRT use for an average of 7 yr. Achilles tendon thickness and cross-sectional areas were determined by ultrasonography, and tendon structural organization was analyzed from the images using linear discriminant analysis (LDA). Maximal voluntary and…
Management of congenital midline nasofrontal dermoid cysts in two identical twins: Case report
2019
Midline dermoid cysts are uncommon lesions that can lead to severe complications when an intracranial extension exists. We report the cases of two twin sisters referred to surgery for removal of the masses and the intracranial extension. They represent an additional example of familial nasal dermoid cysts, providing further support for a genetic basis for the disorder.
Influence of long-term postmenopausal hormone-replacement therapy on estimated structural bone strength: A study in discordant monozygotic twins
2010
Although postmenopausal hormone-replacement therapy (HRT) is known to prevent fractures, knowledge on the influence of long-term HRT on bone strength and its determinants other than areal bone mineral density is scarce. This study used a genetically controlled design with 24 monozygotic female twin pairs aged 54 to 72 years in which one cotwin was using HRT (mean duration 8 years) and the other had never used HRT. Estimated bone strength, cross-sectional area, volumetric bone mineral density, bone mineral mass, and cross-sectional density and mass distributions were assessed in the tibial shaft, distal tibia, and distal radius with peripheral computed tomography (pQCT). In the tibial shaft,…
The world of twins: an update
2010
In last years, owing to the widespread availability of assisted-reproduction technology, multiple pregnancy rates in Western countries have increased. In twin pregnancies, an increased rate of gestational complications, intrauterine growth restriction (IUGR), preterm birth and severe perinatal conditions is present. These complications are more frequent in monozygotic twins compared to dizygotic twins as well as an increased relative risk of chromosomal abnormalities and congenital malformation. Monochorionic twins are at higher risk for complications, since they share a common placenta where an imbalance in unidirectional arteriovenous anastomoses can lead to twin#x2013;twin transfusion sy…