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Beaton AA, Magowan SV, Rudling NG. Does handedness or digit ratio (2D:4D) predict lateralised cognitive ability? PERSONALITY AND INDIVIDUAL DIFFERENCES 2012. [DOI: 10.1016/j.paid.2011.12.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Lenz B, Müller CP, Stoessel C, Sperling W, Biermann T, Hillemacher T, Bleich S, Kornhuber J. Sex hormone activity in alcohol addiction: integrating organizational and activational effects. Prog Neurobiol 2011; 96:136-63. [PMID: 22115850 DOI: 10.1016/j.pneurobio.2011.11.001] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Revised: 11/03/2011] [Accepted: 11/08/2011] [Indexed: 01/06/2023]
Abstract
There are well-known sex differences in the epidemiology and etiopathology of alcohol dependence. Male gender is a crucial risk factor for the onset of alcohol addiction. A directly modifying role of testosterone in alcohol addiction-related behavior is well established. Sex hormones exert both permanent (organizational) and transient (activational) effects on the human brain. The sensitive period for these effects lasts throughout life. In this article, we present a novel early sex hormone activity model of alcohol addiction. We propose that early exposure to sex hormones triggers structural (organizational) neuroadaptations. These neuroadaptations affect cellular and behavioral responses to adult sex hormones, sensitize the brain's reward system to the reinforcing properties of alcohol and modulate alcohol addictive behavior later in life. This review outlines clinical findings related to the early sex hormone activity model of alcohol addiction (handedness, the second-to-fourth-finger length ratio, and the androgen receptor and aromatase) and includes clinical and preclinical literature regarding the activational effects of sex hormones in alcohol drinking behavior. Furthermore, we discuss the role of the hypothalamic-pituitary-adrenal and -gonadal axes and the opioid system in mediating the relationship between sex hormone activity and alcohol dependence. We conclude that a combination of exposure to sex hormones in utero and during early development contributes to the risk of alcohol addiction later in life. The early sex hormone activity model of alcohol addiction may prove to be a valuable tool in the development of preventive and therapeutic strategies.
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Affiliation(s)
- Bernd Lenz
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-University of Erlangen-Nuremberg, Germany.
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Beaton AA, Rudling N, Kissling C, Taurines R, Thome J. Digit ratio (2D:4D), salivary testosterone, and handedness. Laterality 2011; 16:136-55. [DOI: 10.1080/13576500903410369] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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54
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Petricevic B, Cvjeticanin S. Morphogenetic variability and handedness in Montenegro and Serbia. RUSS J GENET+ 2011. [DOI: 10.1134/s1022795411030100] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Heil M, Kavšek M, Rolke B, Beste C, Jansen P. Mental rotation in female fraternal twins: Evidence for intra-uterine hormone transfer? Biol Psychol 2011; 86:90-3. [DOI: 10.1016/j.biopsycho.2010.11.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 11/04/2010] [Accepted: 11/09/2010] [Indexed: 10/18/2022]
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Scerri TS, Brandler WM, Paracchini S, Morris AP, Ring SM, Richardson AJ, Talcott JB, Stein J, Monaco AP. PCSK6 is associated with handedness in individuals with dyslexia. Hum Mol Genet 2010; 20:608-14. [PMID: 21051773 PMCID: PMC3016905 DOI: 10.1093/hmg/ddq475] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Approximately 90% of humans are right-handed. Handedness is a heritable trait, yet the genetic basis is not well understood. Here we report a genome-wide association study for a quantitative measure of relative hand skill in individuals with dyslexia [reading disability (RD)]. The most highly associated marker, rs11855415 (P = 4.7 × 10−7), is located within PCSK6. Two independent cohorts with RD show the same trend, with the minor allele conferring greater relative right-hand skill. Meta-analysis of all three RD samples is genome-wide significant (n = 744, P = 2.0 × 10−8). Conversely, in the general population (n = 2666), we observe a trend towards reduced laterality of hand skill for the minor allele (P = 0.0020). These results provide molecular evidence that cerebral asymmetry and dyslexia are linked. Furthermore, PCSK6 is a protease that cleaves the left–right axis determining protein NODAL. Functional studies of PCSK6 promise insights into mechanisms underlying cerebral lateralization and dyslexia.
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Affiliation(s)
- Thomas S. Scerri
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - William M. Brandler
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Silvia Paracchini
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Andrew P. Morris
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Susan M. Ring
- Department of Social Medicine, University of Bristol, Bristol BS8 2BN, UK
| | - Alex J. Richardson
- Department of Social Policy and Social Work, University of Oxford, OX1 2ER, UK
| | - Joel B. Talcott
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK
| | - John Stein
- Department of Physiology, University of Oxford, Parks Road, Oxford, OX1 3PT, UK and
| | - Anthony P. Monaco
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
- To whom correspondence should be addressed at: Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK. Tel: +44 1865287503; Fax: +44 1865287650;
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Vuoksimaa E, Peter Eriksson CJ, Pulkkinen L, Rose RJ, Kaprio J. Decreased prevalence of left-handedness among females with male co-twins: evidence suggesting prenatal testosterone transfer in humans? Psychoneuroendocrinology 2010; 35:1462-72. [PMID: 20570052 PMCID: PMC2950868 DOI: 10.1016/j.psyneuen.2010.04.013] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 04/19/2010] [Accepted: 04/23/2010] [Indexed: 10/19/2022]
Abstract
Studies of singletons suggest that right-handed individuals may have higher levels of testosterone than do left-handed individuals. Prenatal testosterone levels are hypothesised to be especially related to handedness formation. In humans, female members from opposite-sex twin pairs may experience elevated level of prenatal exposure to testosterone in their intrauterine environment shared with a male. We tested for differences in rates of left-handedness/right-handedness in female twins from same-sex and opposite-sex twin pairs. Our sample consisted of 4736 subjects, about 70% of all Finnish twins born in 1983-1987, with information on measured pregnancy and birth related factors. Circulating testosterone and estradiol levels at age 14 were available on 771 and 744 of these twins, respectively. We found significantly (p=.006) lower prevalence of left-handedness in females from opposite-sex pairs (5.3%) compared to females from same-sex pairs (8.6%). The circulating levels of neither testosterone nor estradiol related to handedness in either females or males. Nor were there differences in circulating testosterone or estradiol levels between females from opposite-sex and same-sex twin pairs. Birth and pregnancy related factors for which we had information were unrelated to handedness. Our results are difficult to fully explain by postnatal factors, but they offer support to theory that relates testosterone to formation of handedness, and in a population-based sample, are suggestive of effects of prenatal testosterone transfer.
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Affiliation(s)
- Eero Vuoksimaa
- Department of Public Health, University of Helsinki, Finland.
| | - C. J. Peter Eriksson
- Department of Alcohol, Drugs and Addiction, National Institute for Health and Welfare, Helsinki, Finland
| | - Lea Pulkkinen
- Department of Psychology, University of Jyväskylä, Finland
| | - Richard J. Rose
- Department of Public Health, University of Helsinki, Finland, Department of Psychological and Brain Sciences, Indiana University, Bloomington, USA
| | - Jaakko Kaprio
- Department of Public Health, University of Helsinki, Finland, Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, Helsinki, Finland, Institute for Molecular Medicine, University of Helsinki, Helsinki, Finland
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Gardener H, Gao X, Chen H, Schwarzschild MA, Spiegelman D, Ascherio A. Prenatal and early life factors and risk of Parkinson's disease. Mov Disord 2010; 25:1560-7. [PMID: 20740569 PMCID: PMC3132935 DOI: 10.1002/mds.23339] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Few studies have investigated the relation between early life factors and risk of Parkinson's disease (PD), although a potential role of exposures during pregnancy and childhood has been hypothesized. The study population comprised participants in two prospective cohorts: the Nurses' Health Study (121,701 female nurses followed up from 1976-2002) and the Health Professionals Follow-up Study (51,529 male health professionals followed up from 1986-2002). PD risk was examined in relation to season of birth, birthweight, parental age at birth, preterm birth, multiple birth, ever having been breast-fed, and handedness. We identified 659 incident PD cases. No significant relation with PD was observed for birthweight, paternal age, preterm birth, multiple birth, and having been breast-fed. A modest nonsignificant association was suggested for season of birth (30% higher risk of PD associated with spring versus winter birth) and for older maternal age at birth (75% increased risk among those with mothers aged 30 years and older versus younger than 20 years). Left-handedness was associated with a 62% increased risk of PD in women but not in men. Further investigation of the relation between prenatal, perinatal, or neonatal factors and PD in other study populations is suggested.
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Affiliation(s)
- Hannah Gardener
- Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA.
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59
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Biological and psychosocial correlates of adult gender-variant identities: A review. PERSONALITY AND INDIVIDUAL DIFFERENCES 2010. [DOI: 10.1016/j.paid.2009.09.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Stoyanov Z, Marinov M, Pashalieva I. Finger Length Ratio (2D:4D) in Left- and Right-Handed Males. Int J Neurosci 2009; 119:1006-13. [DOI: 10.1080/03008200802323883] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Gardener H, Munger K, Chitnis T, Spiegelman D, Ascherio A. The relationship between handedness and risk of multiple sclerosis. Mult Scler 2009; 15:587-92. [PMID: 19389750 PMCID: PMC2771381 DOI: 10.1177/1352458509102622] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Left-handedness has been studied as a marker for in-utero exposure to sex steroid hormones, and an increased risk of autoimmune and immune disorders among left-handed individuals has been suggested. OBJECTIVE This study examines the relationship between hand preference and risk of multiple sclerosis, a presumed autoimmune disorder of unknown etiology. METHODS The study population comprised participants in the Nurses' Health Study, an ongoing prospective cohort study of 121,701 female nurses in the United States with followup from 1976 to 2002. The nurses were asked to report their natural hand preference (right, left, ambidextrous, forced to change). RESULTS During followup 210 incident cases with multiple sclerosis were confirmed. A 62% increased risk of multiple sclerosis was observed among women who were naturally left handed as compared to those who were naturally right handed (95% CI: 1.04-2.53). CONCLUSIONS This study suggests a modest increase in risk of multiple sclerosis among left-handed women. Further investigation of this relationship is suggested in other populations including both males and females. While the current results suggest that prenatal exposure to sex hormones may play a role in multiple sclerosis risk, direct examination of the relationship between in-utero hormone exposure and hand preference is necessary before any conclusions can be drawn.
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Affiliation(s)
- H Gardener
- Department of Epidemiology, Harvard School of Public Health, Boston, MA, 02115, USA.
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62
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Llaurens V, Raymond M, Faurie C. Why are some people left-handed? An evolutionary perspective. Philos Trans R Soc Lond B Biol Sci 2009; 364:881-94. [PMID: 19064347 PMCID: PMC2666081 DOI: 10.1098/rstb.2008.0235] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Since prehistoric times, left-handed individuals have been ubiquitous in human populations, exhibiting geographical frequency variations. Evolutionary explanations have been proposed for the persistence of the handedness polymorphism. Left-handedness could be favoured by negative frequency-dependent selection. Data have suggested that left-handedness, as the rare hand preference, could represent an important strategic advantage in fighting interactions. However, the fact that left-handedness occurs at a low frequency indicates that some evolutionary costs could be associated with left-handedness. Overall, the evolutionary dynamics of this polymorphism are not fully understood. Here, we review the abundant literature available regarding the possible mechanisms and consequences of left-handedness. We point out that hand preference is heritable, and report how hand preference is influenced by genetic, hormonal, developmental and cultural factors. We review the available information on potential fitness costs and benefits acting as selective forces on the proportion of left-handers. Thus, evolutionary perspectives on the persistence of this polymorphism in humans are gathered for the first time, highlighting the necessity for an assessment of fitness differences between right- and left-handers.
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Affiliation(s)
- V Llaurens
- Institut des Sciences de l'Evolution de Montpellier (UMR CNRS 5554), Université de Montpellier, Montpellier Cedex 5, France.
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Vuoksimaa E, Koskenvuo M, Rose RJ, Kaprio J. Origins of handedness: a nationwide study of 30,161 adults. Neuropsychologia 2009; 47:1294-301. [PMID: 19428393 DOI: 10.1016/j.neuropsychologia.2009.01.007] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 12/30/2008] [Accepted: 01/08/2009] [Indexed: 10/21/2022]
Abstract
The origins of human handedness remain unknown. Genetic theories of handedness have received much attention, but some twin studies suggest modest, perhaps negligible genetic effects on handedness. A related question concerning handedness is whether twins have higher rates of left-handedness than do singletons. We studied handedness, with information on forced right-handedness, in a sample of 30,161 subjects aged 18-69 from a questionnaire survey of the older Finnish Twin Cohort. Left-handedness was found to be more common in twins (8.1%) and triplets (7.1%) than in singletons (5.8%), whereas ambidextrousness was more common in triplets (6.4%) than in twins (3.4%) and singletons (3.5%). As in many other studies, males were more likely to be left-handed. Ambidextrous subjects were more likely to become right-handed writers even if not forced to use their right hand. We fit maximum likelihood models to our twin data to estimate the contribution of additive genetic, common environment and unique environmental effects to hand preference. Results, depending on the model, indicate that unique environmental effects account for most observed variance in handedness, both in childhood (92-100%) and adulthood (74-86%). When forced right-handedness was taken into account, estimates of familial effects increased. Concordance for left-handedness in twins is rare, and accordingly, very large samples are needed to detect the familial effects. Our results show that forced-handedness can have an effect on estimates of genetic effects.
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Affiliation(s)
- Eero Vuoksimaa
- Department of Public Health, University of Helsinki, Helsinki, Finland.
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64
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Ypsilanti A, Ganou M, Koidou I, Grouios G. Digit ratio (2D:4D) in individuals with intellectual disability: Investigating the role of testosterone in the establishment of cerebral lateralisation. Laterality 2008; 13:527-44. [DOI: 10.1080/13576500802117164] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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65
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Genetic influences on handedness: data from 25,732 Australian and Dutch twin families. Neuropsychologia 2008; 47:330-7. [PMID: 18824185 DOI: 10.1016/j.neuropsychologia.2008.09.005] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2008] [Revised: 08/12/2008] [Accepted: 09/02/2008] [Indexed: 11/23/2022]
Abstract
Handedness refers to a consistent asymmetry in skill or preferential use between the hands and is related to lateralization within the brain of other functions such as language. Previous twin studies of handedness have yielded inconsistent results resulting from a general lack of statistical power to find significant effects. Here we present analyses from a large international collaborative study of handedness (assessed by writing/drawing or self report) in Australian and Dutch twins and their siblings (54,270 individuals from 25,732 families). Maximum likelihood analyses incorporating the effects of known covariates (sex, year of birth and birth weight) revealed no evidence of hormonal transfer, mirror imaging or twin specific effects. There were also no differences in prevalence between zygosity groups or between twins and their singleton siblings. Consistent with previous meta-analyses, additive genetic effects accounted for about a quarter (23.64%) of the variance (95%CI 20.17, 27.09%) with the remainder accounted for by non-shared environmental influences. The implications of these findings for handedness both as a primary phenotype and as a covariate in linkage and association analyses are discussed.
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66
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Doyen AL, Dufour T, Caroff X, Cherfouh A, Carlier M. Hand preference and hand performance: cross-sectional developmental trends and family resemblance in degree of laterality. Laterality 2008; 13:179-97. [PMID: 18302059 DOI: 10.1080/13576500701764124] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The first aim of the study was to compare developmental trends in the degree of laterality (independent of direction) observed in two handedness tasks. The second aim was to assess family resemblance in the degree of laterality using the same two tasks. The sample was comprised of 186 left-handers and 302 right-handers aged from 6 to 66. Some of the sample were members of the same families. Bishop's card-reaching task was used to assess hand preference, and Annett's peg-moving task to assess manual performance. For the card-reaching task, children aged 7 to 10/11 recorded more midline crossings than the other age groups (both younger and older). No general age-related trend was observed for the Annett pegboard. For the card-reaching task, family resemblance was very low and not significant. The degree of laterality, assessed with the peg-moving task, showed a small but significant resemblance in father-offspring pairs (sons and daughters). Putative involvement of a maternally suppressed gene on chromosome 2p12 and of the androgen receptor was discussed.
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Miller SS, Hoffmann HL, Mustanski BS. Fluctuating asymmetry and sexual orientation in men and women. ARCHIVES OF SEXUAL BEHAVIOR 2008; 37:150-157. [PMID: 18163207 DOI: 10.1007/s10508-007-9256-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The present study measured handedness and bodily fluctuating asymmetry (FA), two markers of developmental instability, in 89 heterosexual and 78 gay men and women. Asymmetry in ear breadth, ear length, ankle breadth, second digit length, fourth digit length, and two composite indices were calculated for each participant and a modified Edinburgh Inventory was used to assess handedness. Results showed that, for men, there was a significant positive correlation between three measures of FA and sexual orientation scores (SOS). As ear breadth FA and two composite FA scores increased so did SOS on a modified Kinsey scale (where 0 indicated exclusive heterosexuality and 6 indicated exclusive homosexuality). No significant relationships were found between SOS and FA for women. Similarly, sexual orientation was not related to handedness for either sex. The theoretical implications of the present results are discussed.
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Affiliation(s)
- Stacie S Miller
- Department of Psychology, Binghamton University, Binghamton, NY 13902-6000, USA.
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68
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Abstract
Androgen receptor (AR) gene has been extensively studied in diverse clinical conditions. In addition to the point mutations, trinucleotide repeat (CAG and GGN) length polymorphisms have been an additional subject of interest and controversy among geneticists. The polymorphic variations in triplet repeats have been associated with a number of disorders, but at the same time contradictory findings have also been reported. Further, studies on the same disorder in different populations have generated different results. Therefore, combined analysis or review of the published studies has been of much value to extract information on the significance of variations in the gene in various clinical conditions. AR genetics has been reviewed extensively but until now review articles have focused on individual clinical categories such as androgen insensitivity, male infertility, prostate cancer, and so on. We have made the first effort to review most the aspects of AR genetics. The impact of androgens in various disorders and polymorphic variations in the AR gene is the main focus of this review. Additionally, the correlations observed in various studies have been discussed in the light of in vitro evidences available for the effect of AR gene variations on the action of androgens.
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MESH Headings
- Androgen-Insensitivity Syndrome/genetics
- Androgen-Insensitivity Syndrome/physiopathology
- Bone Diseases, Metabolic/genetics
- Bone Diseases, Metabolic/physiopathology
- Breast Neoplasms/genetics
- Breast Neoplasms/physiopathology
- Cognition Disorders/genetics
- Cognition Disorders/physiopathology
- Digestive System Diseases/genetics
- Digestive System Diseases/physiopathology
- Female
- Genital Neoplasms, Female/genetics
- Genital Neoplasms, Female/physiopathology
- Genital Neoplasms, Male/genetics
- Genital Neoplasms, Male/physiopathology
- Humans
- Infertility, Male/genetics
- Male
- Muscular Atrophy, Spinal/genetics
- Muscular Atrophy, Spinal/physiopathology
- Phenotype
- Point Mutation
- Polycystic Ovary Syndrome/genetics
- Polycystic Ovary Syndrome/physiopathology
- Polymorphism, Genetic
- Pre-Eclampsia/genetics
- Pre-Eclampsia/physiopathology
- Pregnancy
- Receptors, Androgen/genetics
- Receptors, Androgen/physiology
- Schizophrenia/genetics
- Schizophrenia/physiopathology
- Testosterone/deficiency
- Trinucleotide Repeats
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Affiliation(s)
- Singh Rajender
- Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India
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Luciano M, Hine E, Wright MJ, Duffy DL, MacMillan J, Martin NG. Effects of SCA1, MJD, and DPRLA triplet repeat polymorphisms on cognitive phenotypes in a normal population of adolescent twins. Am J Med Genet B Neuropsychiatr Genet 2007; 144B:95-100. [PMID: 16967484 DOI: 10.1002/ajmg.b.30413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The expansion of unstable trinucleotide CAG repeat polymorphisms of a number of genes causes several neurodegenerative disorders with decreased cognitive function, the severity of the disorder being related to allele length at the triplet repeat locus. While the effects of repeat length have been well studied in clinical samples, there has been little investigation of the effects of triplet repeat variation in the normal range for these genes. We have, therefore, examined linkage and association for three CAG triplet repeat markers (Spinocerebellar Ataxia Type 1, SCA1; Machado-Joseph Disease, MJD; Dentatorubro-pallidoluysian Atrophy, DRPLA) to assess their contribution to variation in cognitive ability (IQ, reading ability, processing speed) in a normal, unselected sample of adolescent twins (248 dizygotic (DZ) sibling pairs, aged 16 years). Association tests, performed in Mx and QTDT, showed a consistent positive association of SCA1 with Arithmetic (P = 0.04). While association was supported between SCA1 and Cambridge reading scores and between DRPLA and inspection time, results were inconsistent across software packages. Given the number of statistical tests performed, it is unlikely that trinucleotide repeat variation in the normal range for these genes influences variation in normal cognition.
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Affiliation(s)
- M Luciano
- Queensland Institute of Medical Research, Brisbane, Australia.
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