Family study of high myopia: association studies

High myopia (more severe than -6.00 Diopters) is one of the leading causes of blindness and vision impairment in the world. Its prevalence has rapidly been growing and the estimated number of myopic people worldwide is expected to be 2.5 billion by the year 2020. My experimental work covered three topics: (1) characterization of the quantity and quality of mouth wash-extracted DNA (2) genetic association studies, and (3) evaluation of an imprinting effect in high myopia. Mouthwash-derived DNA is an important source of human DNA for large-scale genetic studies. Thus, potential methods of DNA quantification (spectrophotometry, fluorometry, gel electrophoresis and qPCR) and quality assessment (gel electrophoresis and PCR) were evaluated. Regarding DNA quantification methods, fluorometry compared favorably to the gold-standard qPCR. DNA quality assessments revealed that -10% of collected buccal DNA samples were severely degraded—a phenomenon that was shown to be partly subject-specific. Myopia association studies were performed for: genes in MYP regions, the myocilin gene, the collagen type I alpha 1 gene and the collagen type II alpha 1 gene. These genes have been linked to myopia because of their function and/or previous positive findings. All tests were performed on a combined dataset of complex high myopia pedigrees and cases/controls, applying likelihood ratio statistics and Bonferroni correction to account for multiple testing. The results suggested that none of the genes examined have an important influence on susceptibility to high myopia. There is greater resemblance of refractive error between siblings than between parents and offspring, implying the possibility of imprinting in the aetiology of myopia. Thus, tests for imprinting were performed on "trio" pedigrees, applying Z-score and T2-test statistics and permutation to account for multiple testing. The results tentatively suggested that parent-of- origin effects and/or by maternal effects contribute to myopia development

The Examination of Remodeling Processes of Hard Periodontal Tissues in Rats with Disorders of Pancreatic Incretory Function

Topicality. Pancreatic hormones play an important role in the process of remodeling of hard periodontal tissues. Violations of carbohydrate metabolism that occur under conditions of isolated insulin resistance (IR) and in combination with iodine deficiency (ID) can be the cause of dysmetabolic disorders of mineralization/demineralization physiological system of tooth-maxillary complex. The aim. To study the changes of remodeling processes of hard periodontal tissues in rats with isolated IR and impaired glucose tolerance against the background of ID. Materials and methods. The examination was carried on 90 male rats, which were divided into three groups: control (intact animals), group of rats with IR under conditions of adequate iodine supply, and with IR against the background of ID. The system of carbohydrate metabolism was studied by the level of insulin in blood serum, glucose and glycosylated hemoglobin (HbA1c) of blood with the following calculation of HOMA-IR index. The processes of mineralization/demineralization were detected by the content of calcium, magnesium, zinc, manganese, copper in cementum of tooth root and alveolar process, and by the activity of acid and alkaline phosphatases in blood serum. Results. Keeping of animals on a high-fructose diet led to the development of carbohydrate metabolism disorders (increase blood glucose and HbA1c levels, blood serum insulin, HOMA-IR index) and changes of remodeling processes in hard periodontal tissues (decrease the level of calcium, magnesium and manganese against the background of increase the zinc content in cementum of tooth root; decrease the content of macroelements in alveolar process; activation of acid phosphatase against the background of inhibition of alkaline phosphatase activity). The development of combined endocrinopathy was accompanied by more pronounced changes of studied parameters. Conclusions. The violation of glucose tolerance against the background of ID slows down the mineralization processes of hard periodontal tissues mainly due to the intensification of osteoresorptive processes. Keywords: acid and alkaline phosphatases; calcium homeostasis; bioelement panel of tooth-maxillary system; insulin resistance; iodine deficiency.Актуальність. Важливу роль у процесі  ремоделювання твердих тканин пародонта відіграють гормони підшлункової залози. Порушення обміну вуглеводів, які виникають за умов ізольованої інсулінорезистентності (ІР) та у поєднанні з йододефіцитом (ЙД)  можуть  бути причиною дисметаболічних розладів у системі фізіологічної мінералізації/демінералізації зубоальвеолярного комплесу. Мета. Вивчити зміни процесів ремоделювання твердих тканин пародонта у щурів із ізольованою ІР та порушеною толерантністю до глюкози на тлі ЙД. Матеріали і методи. Дослідження проведені на 90 щурах-самцях, які були розділені на три групи: контрольну (інтактні тварини), групу щурів з ІР за умов належного забезпечення йодом та з ІР на тлі ЙД. Систему вуглеводного обміну досліджували за рівнем інсуліну в сироватці крові, глюкози й глікозильованого гемоглобіну крові (HbА1с) із наступним розрахунком індексу HOMA-IR.  Процеси мінералізації/демінералізації вивчали за вмістом кальцію, магнію, цинку, марганцю, міді у цементі кореня зуба й комірковому відростку та за активністю кислої й лужної фосфатаз сироватки крові. Результати. Перебування тварин на високофруктозній дієті призвело до розвитку порушень вуглеводного обміну (збільшення рівня глюкози й HbА1с крові, інсуліну сироватки крові, індексу HOMA-IR) та змін процесів ремоделювання твердих тканин пародонта (зниження рівня кальцію, магнію та марганцю на тлі зростання вмісту цинку у цементі кореня зуба; зменшення вмісту макроелементів у комірковому відростку; активація кислої фосфатази на тлі пригнічення активності лужної фосфатази). Розвиток комбінованої ендокринопатії супроводжувався більш вираженими змінами досліджуваних показників. Висновки. Порушення толерантності до глюкози на тлі ЙД сповільнює процеси мінералізації твердих тканин пародонта головним чином за рахунок інтенсифікації остеорезобтивних поцесів. Ключові слова: кисла та лужна фосфатази; кальцієвий гомеостаз; біоелементна панель зубощелепної системи; інсулінорезистентність; йододефіцит

Quality of DNA Extracted from Mouthwashes

Background A cost effective, safe and efficient method of obtaining DNA samples is essential in large scale genetic analyses. Buccal cells are an attractive source of DNA, as their collection is non-invasive and can be carried out by mail. However, little attention has been given to the quality of DNA extracted from mouthwashes. Methodology Mouthwash-derived DNA was extracted from 500 subjects participating in a genetic study of high myopia. DNA quality was investigated using two standard techniques: agarose gel electrophoresis and quantitative polymerase chain reaction (qPCR). Principal Findings Whereas the majority of mouthwash-derived DNA samples showed a single band of high molecular weight DNA by gel electrophoresis, 8.9% (95% CI: 7.1–10.7%) of samples contained only a smear of low-to-medium molecular weight, degraded DNA. The odds of DNA degradation in a subject's second mouthwash sample, given degradation of the first, was significantly greater than one (OR = 3.13; 95% CI: 1.22–7.39; Fisher's test P = 0.009), suggesting that DNA degradation was at least partially a subject-specific phenomenon. Approximately 12.4% (95% CI: 10.4–14.4%) of mouthwash-derived DNA failed to PCR amplify efficiently (using an ~200 bp microsatellite marker). However, we found there was no significant difference in amplification success rate between DNA samples judged to be degraded or non-degraded by gel electrophoresis (Fisher's test P = 0.5). Conclusions This study demonstrated that DNA degradation affects a significant minority of saline mouthwashes, and that the phenomenon is partially subject-specific. Whilst the level of degradation did not significantly prevent successful amplification of short PCR fragments, previous studies suggest that such DNA degradation would compromise more demanding applications

Myocilin polymorphisms and high myopia in subjects of European origin

Purpose: Three previous studies have tested for an association between high myopia and polymorphisms in the open angle glaucoma gene, myocilin (MYOC), all in subjects of Chinese ethnicity. In two of the studies, a significant association was found while in the third, there was no association. We sought to investigate the association between high myopia and polymorphisms in MYOC in subjects of European ethnicity. Methods: Subjects were recruited from two sites, Cardiff University in the UK and Duke University in the United States. The Cardiff University cohort was comprised of 164 families with high myopia (604 subjects) plus 112 unrelated, highly myopic cases and 114 emmetropic controls. The Duke University cohort was comprised of 87 families with high myopia (362 subjects) plus 59 unrelated, highly myopic cases. Subject DNA was genotyped with a panel of MYOC single nucleotide polymorphisms (SNPs) including those found previously associated with high myopia. The Cardiff cohort was also genotyped for two flanking microsatellite markers analyzed in prior studies. Association between high myopia and MYOC polymorphisms was assessed using the Unphased program. Results: Since there was no evidence of heterogeneity in genotype frequencies between families and singleton samples or between cohorts, both subject groups (families and unrelated subjects) from both recruitment sites were analyzed jointly for those SNPs genotyped in common. Two variants showed significant association before correction for multiple testing. These two variants were rs16864720 (p=0.043) and NGA17 (p=0.026). However, there was no significant association after Bonferroni correction. The estimated relative risk (RR) conferred by each of the MYOC variants was low (RR<1.5). Conclusions: Our results suggest that MYOC polymorphisms have a very low, or possibly negligible, influence on high myopia susceptibility in subjects of European ethnicity

Assessing the contribution of genetic nurture to refractive error

Parents pass on both their genes and environment to offspring, prompting debate about the relative importance of nature versus nurture in the inheritance of complex traits. Advances in molecular genetics now make it possible to quantify an individual’s genetic predisposition to a trait via his or her ‘polygenic score’. However, part of the risk captured by an individual’s polygenic score may actually be attributed to the genotype of their parents. In the most well-studied example of this indirect ‘genetic nurture’ effect, about half the genetic contribution to educational attainment was found to be attributed to parental alleles, even if those alleles were not inherited by the child. Refractive errors, such as myopia, are a common cause of visual impairment and pose high economic and quality-of-life costs. Despite strong evidence that refractive errors are highly heritable, the extent to which genetic risk is conferred directly via transmitted risk alleles or indirectly via the environment that parents create for their children is entirely unknown. Here, an instrumental variable analysis in 1944 pairs of adult siblings from the United Kingdom was used to quantify the proportion of the genetic risk (‘single nucleotide polymorphism (SNP) heritability’) of refractive error contributed by genetic nurture. We found no evidence of a contribution from genetic nurture: non-within-family SNP-heritability estimate = 0.213 (95% confidence interval 0.134–0.310) and within-family SNP-heritability estimate = 0.250 (0.152–0.372). Our findings imply the genetic contribution to refractive error is principally an intrinsic effect from alleles transmitted from parents to offspring

Exome chip analyses in adult attention deficit hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable childhood-onset neuropsychiatric condition, often persisting into adulthood. The genetic architecture of ADHD, particularly in adults, is largely unknown. We performed an exome-wide scan of adult ADHD using the Illumina Human Exome Bead Chip, which interrogates over 250 000 common and rare variants. Participants were recruited by the International Multicenter persistent ADHD CollaboraTion (IMpACT). Statistical analyses were divided into 3 steps: (1) gene-level analysis of rare variants (minor allele frequency (MAF)o1%); (2) single marker association tests of common variants (MAF⩾1%), with replication of the top signals; and (3) pathway analyses. In total, 9365 individuals (1846 cases and 7519 controls) were examined. Replication of the most associated common variants was attempted in 9847 individuals (2077 cases and 7770 controls) using fixed-effects inverse variance meta-analysis. With a Bonferroni-corrected significance level of 1.82E − 06, our analyses of rare coding variants revealed four study-wide significant loci: 6q22.1 locus (P = 4.46E − 08), where NT5DC1 and COL10A1 reside; the SEC23IP locus (P = 6.47E − 07); the PSD locus (P = 7.58E − 08) and ZCCHC4 locus (P = 1.79E − 06). No genome-wide significant association was observed among the common variants. The strongest signal was noted at rs9325032 in PPP2R2B (odds ratio = 0.81, P = 1.61E − 05). Taken together, our data add to the growing evidence of general signal transduction molecules (NT5DC1, PSD, SEC23IP and ZCCHC4) having an important role in the etiology of ADHD. Although the biological implications of these findings need to be further explored, they highlight the possible role of cellular communication as a potential core component in the development of both adult and childhood forms of ADHD

A variant in LIN28B is associated with 2D:4D finger-length ratio, a putative retrospective biomarker of prenatal testosterone exposure

The ratio of the lengths of an individual's second to fourth digit (2D:4D) is commonly used as a noninvasive retrospective biomarker for prenatal androgen exposure. In order to identify the genetic determinants of 2D:4D, we applied a genome-wide association approach to 1507 11-year-old children from the Avon Longitudinal Study of Parents and Children (ALSPAC) in whom 2D:4D ratio had been measured, as well as a sample of 1382 12- to 16-year-olds from the Brisbane Adolescent Twin Study. A meta-analysis of the two scans identified a single variant in the LIN28B gene that was strongly associated with 2D:4D (rs314277: p = 4.1 108) and was subsequently independently replicated in an additional 3659 children from the ALSPAC cohort (p = 1.53 106). The minor allele of the rs314277 variant has previously been linked to increased height and delayed age at menarche, but in our study it was associated with increased 2D:4D in the direction opposite to that of previous reports on the correlation between 2D:4D and age at menarche. Our findings call into question the validity of 2D:4D as a simplistic retrospective biomarker for prenatal testosterone exposure

Genome wide association study identifies variants in NBEA associated with migraine in bipolar disorder

C. Liu, J. Wedenoja, M. Kaunisto, K. Heikkilä, J. Kaprio, M. Wessman, M. Kallela, M. Färkkilä, V. Artto, J. Eriksson, A. Palotie, M. Daily työryhmän BiGs Consortium IHG Consortium jäseniä.Peer reviewe