Genetic and Environmental Influences on Schizotypy among Adolescents in Taiwan: A Multivariate Twin/sibling Analysis

This study aimed to examine the relative contribution of genes and environment to psychometrically measured schizotypy and the causes for the covariation between different dimensions of schizotypy in a total of 330 pairs of twins and 36 same-sex sib-pairs aged 12–16 and systematically recruited from junior high schools in Taipei. Twins’ zygosity was determined by a combination of DNA typing and physical similarity. Schizotypy was measured using the Perceptual Aberration Scale (PAS) as well as the Schizotypal Personality Questionnaire (SPQ) and its three factors (Cognitive-perceptual Dysfunction, Disorganization, and Interpersonal Dysfunction). Univariate analyses of structural equation modeling using Mx program showed that scores on these schizotypal measures were substantially heritable (h ² ranging from 41 to 49%), with some genetic effects being non-additive. Multivariate analyses revealed common genetic factors linking between various traits of schizotypy, with bivariate heritability ranging from 50 to 65%. The proportion of the genetic contributions not shared with the other measures of schizotypy ranged from 24% for the Disorganization to 49% for the PAS scores. We concluded that there exist both common and specific genetic factors between the various dimensions of schizotypy, and at least half of their correlations were genetic in nature. Edited by Peter McGuffin     

Neonatal small left colon syndrome in twins

There are no previous reports of small left colon syndrome in twins. Small left colon syndrome is reported in 2 sets of twins. In 1 set 1 twin had clinical and radiographic signs of small left colon syndrome. The sib was clinically normal and had no radiographic studies. In the other set, both twins hadidentical clinical and radiographic findings of hyperplastic left colon. This suggests a genetic and/or environmental intrauterine, rather than a postpartum etiology for the small left colon syndrome.     

Birth weight,infant growth,and adolescent blood pressure using twin status as an instrumental variable in a Chinese birth cohort: “Children of 1997”

PurposeTo evaluate the credibility of twin status as an instrumental variable for birth weight and infant growth and to obtain less-confounded estimates of the associations of birth weight or infant growth with adolescent blood pressure (BP).MethodsProspective population-based “Children of 1997” birth cohort of all surviving infants born in Hong Kong, China, from April to May 1997 with sex-, age-, and height-specific BP z-score at approximately 11 years (n = 6276) and approximately 13 years (n = 5305).ResultsIn instrumental variable analyses, birth weight-for-gestational age z-score was not associated with z-score for systolic BP (0.01; 95% confidence interval [CI], −0.22 to 0.25) or diastolic BP (0.04; 95% CI, −0.09 to 0.18) at approximately 11 years adjusted for maternal age and migrant status (F = 38.6). Change in weight z-score at 0 to 12 months was not associated with z-score for systolic BP (−0.003; 95% CI, −0.15 to 0.15) or diastolic BP (−0.02; 95% CI, −0.10 to 0.07) at approximately 11 years (F = 54.4). Estimates were similar for BP at approximately 13 years, although the F-statistic was lower.ConclusionsBirth weight and infant growth may make little contribution to adolescent BP. Extending consideration of the effects of early life to other growth periods, such as puberty, on BP might yield public health benefits.     

Analysis of heritability of hormonal responses to alcohol in twins: beta-endorphin as a potential biomarker of genetic risk for alcoholism

BACKGROUND: Hormonal responses to alcohol have been reported to differ in subjects with and without a family history of alcoholism which suggests that alcohol-induced hormonal changes might be used to identify individuals who are at elevated genetic risk for developing alcoholism. However, before a biological response can be used as a marker of genetic risk for disease, it must first be demonstrated that the response is, in fact, heritable. The present study was designed to determine whether hormonal responses to alcohol are heritable. METHODS: The adrenocorticotropic hormone (ACTH), beta-endorphin (beta-E), cortisol (CORT), and prolactin (PRL) responses to alcohol were examined in male and female identical (monozygotic or MZ) and fraternal (dizygotic or DZ) twin pairs. Male subjects consumed 0.35 g ethanol/kg body weight (BW) and females consumed 0.325 g ethanol/kg BW in each of two alcohol drinking sessions administered 1 hr apart (total dose of 0.7 g/kg BW in males and 0.65 g/kg BW in females). Plasma hormone content was analyzed in samples collected before (resting conditions) and at 15, 60, 75, 120, 180, and 240 min after onset of drinking. Hormonal responses to alcohol were examined with twin analyses using the TWINAN90 program. A separate analysis was performed for each of the four hormones. A subset of subjects from each zygosity was seen on two separate occasions to establish retest reliability. Heritability of hormonal responses to alcohol was estimated using the intraclass correlation approach before and after removing the contribution of covariates that have the potential of influencing the plasma levels of these hormones. RESULTS: Resting plasma levels of all four hormones were within the expected range, and the beta-E, ACTH, and PRL responses to the alcohol challenge evidenced good test-retest reliability. Of the four hormones examined, the only one that showed significant heritability after alcohol drinking was beta-E. Heritability estimates were not altered for any of the four hormones after removal of the variance contributed by covariates, such as gender and age. CONCLUSIONS: Taken together with other recent findings, the results suggest that the beta-E response to alcohol may represent a new biomarker that can be used to identify individuals who are at elevated genetic risk for developing alcoholism.     

Genetic factors and fetal growth sex constitution and birthweight in twins

Fetal growth is considered a multifactorially-influenced characteristic. Genetic factors were found to play the main role in fetal growth determination, and it is the polygenic inheritance. The paper reviews the birthweights of 360 unlike-sexed two-egg twins, born at the Clinic of Gynecology and Obstetrics, Faculty of Medicine in Beograd, from January 1, 1970 through June 30, 1984. The mean birthweight differences between the male (2954.94 +/- 704.28 g) and female (2313.19 +/- 651.32 g) fetuses, amounted to 141.75 g. The difference is highly significant (P less than 0.01); variation coefficient shows that the examined groups were homogenous (VC was below 30%). The results were discussed from the genetic point of view, and particularly from the point of view of sex constitution, with special respect to the effect of Y chromosome on fetal growth. It has been known that human somatic development, body weight, bone maturation and teeth development are influenced by variety of factors. In addition to nutritional and other factors of the external environment, genetic and humoral factors are leading. The fact that fetuses with XY male constitution are heavier at birth than female fetuses with XX constitution, made us consider the correlation between genotype-phenotype, and the mentioned characteristics. This study was aimed at finding out the role of genetic factors in fetal growth, with respect to sex constitution, particularly to chromosome effect on fetal growth in unlike-sexed two-egg twins.     

Increased D-dimer levels in twin gestation

In normal pregnancy, the hemostatic balance is displaced toward hypercoagulability. The elevation in plasma levels of coagulation factors VII, VIII, and X and fibrinogen and the increased concentrations of plasminogen activator inhibitors [1,2] may predispose individuals to thromboembolism, especially near term [1,3]. Because human multifetal gestation requires still greater physiological alterations, the imbalance in hemostasis is further exaggerated. It has been suggested that the changes in the coagulation system near term may even mimic low-grade disseminated intravascular coagulopathy [4]. However, for the majority of women with multifetal gestation, the coagulopathy observed in the laboratory is not clinically apparent [5]. Despite the large body of research on the physiological adaptation to pregnancy, relatively little is known of the biological adaptation in general and the hemostatic changes in particular associated with multiple gestation.     

双胞胎新生儿患呼吸窘迫综合征风险差异的研究

目的 探讨双胞胎新生儿患呼吸窘迫综合征(RDS)的风险差异及原因.方法 采用回顾性研究方法对328例双胞胎新生儿进行Logistic回归分析、卡方及t检验、等级相关检验等.结果 Logistic回归分析发现胎龄(OR=1.367,P=0.040)、出生体质量(OR=1.416,P=0.013)、Apgar评分(OR=5.054.P=O)是RDS主要危险因素;卡方检验发现双胞胎之间患RDS有差异(γ2=10.370,P=O.001);等级相关检验发现出生体质量、Apgar评分及呼吸频率与RDS相关;t检验发现病例组双胞胎之间Apgar评分(t=3.766,P=0)、呼吸频率(t=3.528,P=0.001)有显著差异,而出生体质量、入院体温、心率之间没有显著差异.结论 双胞胎之间患RDS风险有差异,双胞胎第二婴具有更高风险,这可能与其更易发生窒息有关.     

Determination of chorionicity in twin gestations by high-frequency abdominal ultrasonography: Counting the layers of the dividing membrane

OBJECTIVE: Our aim was to determine whether chorionicity in twin gestations can be diagnosed by use of high-frequency ultrasonography to count the layers of intraamniotic membrane. STUDY DESIGN: This prospective study of 66 twin pregnancies between 13 and 38 weeks' gestation used transabdominal ultrasonography at 10 MHz. The pregnancy was classified as monochorionic when two layers were counted and as dichorionic when three or four layers were counted. The findings of the examiner, who had no other information about chorionicity, were compared with those of the histopathologic examination of the placenta. RESULTS: Ultrasonography allowed chorionicity to be determined correctly in 60 of 63 cases (95%; 100% in the second trimester and 92% in the third). The predictive value for dichorionicity was 100% (48/48) and the sensitivity 94% (48/51). The 12 monochorionic diamniotic pregnancies in which the membrane was visualized were all correctly diagnosed. In a thirteenth case, with severe oligohydramnios, the membrane could not be seen. Two patients were lost to follow-up. In 95% of the cases (63/66) only one examination was required to diagnose chorionicity. Intraobserver variability was 0% (0/26). Interobserver variability, tested by photographs, was 3% (2/65). CONCLUSIONS: This technique should be the first-line method for determining chorionicity in the second and third trimesters because it is the most effective. Its excellent reproducibility may be attributable to the use of high-frequency ultrasonography. (Am J Obstet Gynecol 1996;175:1529-33.)     

乙型肝炎病毒感染后表型不一致的单卵孪生子基因组CpG岛甲基化谱差异分析

目的进行乙型肝炎病毒感染后表型不一致的单卵孪生子基因组CpG岛甲基化谱差异分析,以发现可能的差异甲基化基因。方法采用改良甲基化间区位点扩增技术,根据人基因组CpG岛甲基化位点的两种主要碱基组合,-CGCG-和-CCGG-,用3种不同的酶切组合（SmaⅠ—XmaⅠ、HpaⅡ-MspⅠ、BssHⅡ—PauⅠ／BsePⅠ）,同时采用Personal Molecular Imager FX分子成像系统及放射自显影相结合的方法,经Quantity One 4．4．0凝胶图像分析软件进行差异条带分析,分离回收差异甲基化条带并克隆人T载体,阳性克隆进行测序,将测序结果进行BLAST分析,初步了解与乙型肝炎病毒感染后表型不一致的单卵孪生子相关的差异甲基化基因情况。结果在一对表型一致的单卵孪生子间基因组CpG岛甲基化分析显示条带几乎相同,而在另一对表型一致以及一对表型不一致的单卵孪生子之间均存在差异甲基化条带,前者差异甲基化条带数目少于后者,将得到的差异甲基化条带克隆人T载体,目前测序分析得到4个可能与乙型肝炎病毒感染后表型不一致的单卵孪生子相关的差异甲基化基因。结论乙型肝炎病毒感染后表型不一致的单卵孪生子间基因组CpG岛甲基化水平有差异,其对疾病表型的影响及机制尚需后续深入研究。