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Kyselicová K, Belica I, Vidošovičová M, Janšáková K, Neščáková E, Špajdel M, Navarová S, Ostatníková D. Autism spectrum disorder and new perspectives on the reliability of second to fourth digit ratio. Dev Psychobiol 2021; 63:e22122. [PMID: 33942898 DOI: 10.1002/dev.22122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 02/01/2021] [Accepted: 03/19/2021] [Indexed: 11/06/2022]
Abstract
The second to fourth digit ratio (2D:4D) is according to previous studies a likely biomarker for prenatal testosterone exposure and its effect on the human brain. It was found to be linked to autism spectrum disorders (ASD). Recently, 2D:4D raised a lot of questions with regard to its stability and autism-related behaviors. Here, we present a cross-sectional study of 2D:4D in boys (N = 91, mean age 7.63) and adults (N = 36 mean age 22.8) with ASD as well as neurotypical students, 506 participants in total. Digit ratio was assessed by taking measurements from digital scans, compared between groups and correlated with the autism quotient. Significant differences were found in the digit ratio of children and adults. Both girls and boys had 2D:4D ratio lower than women and men, both on the right (p = 0.000 in females, p = 0.000 in males) and left hand (p = 0.018 in females, p = 0.011 in males). No significant differences were found in digit ratios between neurotypical subjects and those with ASD nor was there a relationship with the reported autistic traits, which leads us to question the reliability of 2D:4D and its relation to ASD.
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Affiliation(s)
- Klaudia Kyselicová
- Institute of Physiology, Academic Research Center for Autism, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Ivan Belica
- Institute of Physiology, Academic Research Center for Autism, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Mária Vidošovičová
- Institute of Physiology, Academic Research Center for Autism, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Katarína Janšáková
- Institute of Physiology, Academic Research Center for Autism, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Eva Neščáková
- Department of Anthropology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Marián Špajdel
- Department of Psychology, Faculty of Philosophy and Arts, Trnava University, Trnava, Slovakia
| | - Simona Navarová
- Department of Psychology, Faculty of Philosophy and Arts, Trnava University, Trnava, Slovakia
| | - Daniela Ostatníková
- Institute of Physiology, Academic Research Center for Autism, Faculty of Medicine, Comenius University, Bratislava, Slovakia
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Fusar-Poli L, Rodolico A, Sturiale S, Carotenuto B, Natale A, Arillotta D, Siafis S, Signorelli MS, Aguglia E. Second-to-Fourth Digit Ratio (2D:4D) in Psychiatric Disorders: A Systematic Review of Case-control Studies. CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE : THE OFFICIAL SCIENTIFIC JOURNAL OF THE KOREAN COLLEGE OF NEUROPSYCHOPHARMACOLOGY 2021; 19:26-45. [PMID: 33508786 PMCID: PMC7851454 DOI: 10.9758/cpn.2021.19.1.26] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/24/2020] [Accepted: 07/26/2020] [Indexed: 12/22/2022]
Abstract
The second-to-fourth digit ratio (2D:4D) is an indirect, retrospective, non-invasive measure that correlates negatively with intrauterine exposure to testosterone. The present meta-analysis aimed to evaluate if 2D:4D differs between patients with psychiatric disorders and controls. In September 2019, we searched in Web of Knowledge, PsycINFO, Embase, and CINHAL, and retrieved 619 papers. We finally included 43 case-control studies which compared the 2D:4D ratio of patients with autism spectrum disorder (ASD) (n = 16), schizophrenia (n = 8), gender non-conformity (n = 7), addictions (n = 5), attention deficit-hyperactivity disorder (ADHD) (n = 4), mood disorders (n = 2), and intellectual disability (n = 1) to non-clinical controls. Meta-analyses showed that, overall, psychiatric patients had lower 2D:4D than healthy controls (n = 43, overall sample = 9,484, mean difference = -0.0056, 95% confidence interval from -0.0093 to -0.002, I2 = 74%), with more pronounced differences in the right hand, males, and children. Considering psychiatric disorders individually, significant differences were found in the ASD, ADHD, and addictions groups, in which 2D:4D was significantly lower than healthy controls. Conversely, the right hand of males with schizophrenia showed higher 2D:4D than healthy controls. No other significant differences were detected. Although our results need to be cautiously interpreted and find limited applications in clinical practice, they may suggest that 2D:4D is altered in some psychopathological conditions, underlining the role of prenatal exposure to sex steroids in the etiology of psychiatric disorders.
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Affiliation(s)
- Laura Fusar-Poli
- Department of Clinical and Experimental Medicine, Psychiatry Unit, University of Catania, Catania, Italy
| | - Alessandro Rodolico
- Department of Clinical and Experimental Medicine, Psychiatry Unit, University of Catania, Catania, Italy
| | - Serena Sturiale
- Department of Clinical and Experimental Medicine, Psychiatry Unit, University of Catania, Catania, Italy
| | - Bianca Carotenuto
- Department of Clinical and Experimental Medicine, Psychiatry Unit, University of Catania, Catania, Italy
| | - Antimo Natale
- Department of Clinical and Experimental Medicine, Psychiatry Unit, University of Catania, Catania, Italy
| | - Davide Arillotta
- Department of Clinical and Experimental Medicine, Psychiatry Unit, University of Catania, Catania, Italy
| | - Spyridon Siafis
- Department of Psychiatry and Psychotherapy, School of Medicine, Technical University of Munich, Munich, Germany
| | - Maria Salvina Signorelli
- Department of Clinical and Experimental Medicine, Psychiatry Unit, University of Catania, Catania, Italy
| | - Eugenio Aguglia
- Department of Clinical and Experimental Medicine, Psychiatry Unit, University of Catania, Catania, Italy
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Richards G, Medland SE, Beaton AA. Digit ratio (2D:4D) and handedness: A meta-analysis of the available literature. Laterality 2021; 26:421-484. [PMID: 33517845 DOI: 10.1080/1357650x.2020.1862141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The Geschwind-Behan-Galaburda and sexual differentiation models predict an association between elevated foetal androgen exposure and left-handedness whereas the callosal hypothesis predicts the opposite. We present a meta-analysis of correlations between handedness and digit ratio (2D:4D), a putative marker of prenatal testosterone. Left-handedness predicted low (male-typical) right-hand digit ratio (R2D:4D), high (female-typical) left-hand digit ratio (L2D:4D), and low R2D:4D-L2D:4D directional asymmetry (D[R-L]). Effect sizes were extremely small and not moderated by sex or method of measuring handedness or 2D:4D. The same general pattern was observed after excluding the very large study (110,329 males, 90,412 females) of Manning and Peters ([2009]. Digit ratio (2D:4D) and hand preference for writing in the BBC Internet Study. Laterality: Asymmetries of Body, Brain and Cognition, 14(5), 528-540. doi:10.1080/13576500802637872); however, no significant effects for R2D:4D were observed once these samples were removed. The results do not confirm any theory linking prenatal androgens with handedness, so we speculate they instead reflect the mechanical action of writing causing subtle changes in the musculature and/or fat pads of the fingers. Gripping a pen/pencil might cause an increase in 2D relative to 4D (and/or decrease in 4D relative to 2D) resulting in higher ratios on the writing-hand; furthermore, this could differ between left- and right-handers due to writing in the left-to-right direction (as in English) having asymmetrical effects depending on which hand is used.
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Affiliation(s)
- Gareth Richards
- School of Psychology, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK.,Centre for Research on Play in Education, Development & Learning, Faculty of Education, University of Cambridge, Cambridge, UK
| | - Sarah E Medland
- Psychiatric Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia.,School of Psychology, University of Queensland, St Lucia, Australia.,School of Psychology and Counselling, Queensland University of Technology, Brisbane, Australia
| | - Alan A Beaton
- Department of Psychology, School of Human & Health Sciences, Swansea University, Swansea, UK.,Department of Psychology, Aberystwyth University, Aberystwyth, UK
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Schieve LA, Tian L, Dowling N, Croen L, Hoover-Fong J, Alexander A, Shapira SK. Associations Between the 2nd to 4th Digit Ratio and Autism Spectrum Disorder in Population-Based Samples of Boys and Girls: Findings from the Study to Explore Early Development. J Autism Dev Disord 2018; 48:2379-2395. [PMID: 29450837 PMCID: PMC5997499 DOI: 10.1007/s10803-018-3495-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The ratio of the index (2nd) finger to ring (4th) finger lengths (2D:4D) is a proxy for fetal testosterone and estradiol. Studies suggesting 2D:4D is inversely associated with autism spectrum disorder (ASD) in males were limited by lack of confounder and subgroup assessments. Studies of females are sparse. We examined associations between ASD and 2D:4D among children in the Study to Explore Early Development; we considered case subgroups and numerous potential demographic and maternal-perinatal health confounders. We observed a modest inverse association between ASD and right-hand 2D:4D in males; subgroup analyses indicated associations were limited to ASD cases with birth defects/genetic syndromes or dysmorphic features. We observed a positive association between ASD and left-hand 2D:4D in females, overall and within most case subgroups.
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Affiliation(s)
- Laura A Schieve
- National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Mailstop E-86, 4770 Buford Hwy NE, Atlanta, GA, 30341, USA.
| | - Lin Tian
- National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Mailstop E-86, 4770 Buford Hwy NE, Atlanta, GA, 30341, USA
| | - Nicole Dowling
- National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Mailstop E-86, 4770 Buford Hwy NE, Atlanta, GA, 30341, USA
| | - Lisa Croen
- Kaiser Permanente Division of Research, Oakland, CA, USA
| | - Julie Hoover-Fong
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Aimee Alexander
- National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Mailstop E-86, 4770 Buford Hwy NE, Atlanta, GA, 30341, USA
| | - Stuart K Shapira
- National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Mailstop E-86, 4770 Buford Hwy NE, Atlanta, GA, 30341, USA
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Barona M, Kothari R, Skuse D, Micali N. Social communication and emotion difficulties and second to fourth digit ratio in a large community-based sample. Mol Autism 2015; 6:68. [PMID: 26715984 PMCID: PMC4693443 DOI: 10.1186/s13229-015-0063-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 12/18/2015] [Indexed: 12/02/2022] Open
Abstract
Background Recent research investigating the extreme male brain theory of autism spectrum disorders (ASD) has drawn attention to the possibility that autistic type social difficulties may be associated with high prenatal testosterone exposure. This study aims to investigate the association between social communication and emotion recognition difficulties and second to fourth digit ratio (2D:4D) and circulating maternal testosterone during pregnancy in a large community-based cohort: the Avon Longitudinal Study of Parents and Children (ALSPAC). A secondary aim is to investigate possible gender differences in the associations. Methods Data on social communication (Social and Communication Disorders Checklist, N = 7165), emotion recognition (emotional triangles, N = 5844 and diagnostics analysis of non-verbal accuracy, N = 7488) and 2D:4D (second to fourth digit ratio, N = 7159) were collected in childhood and early adolescence from questionnaires and face-to-face assessments. Complete data was available on 3515 children. Maternal circulating testosterone during pregnancy was available in a subsample of 89 children. Results Males had lower 2D:4D ratios than females [t (3513) = −9.775, p < 0.001]. An association was found between measures of social communication and emotion recognition, and the lowest 10 % of 2D:4D ratios. A significant association was found between maternal circulating testosterone and left hand 2D:4D [OR = 1.65, 95 % CI 1.1–2.4, p < 0.01]. Conclusions Previous findings on the association between 2D:4D and social communication difficulties were not confirmed. A novel association between an extreme measure of 2D:4D in males suggests threshold effects and warrants replication. Electronic supplementary material The online version of this article (doi:10.1186/s13229-015-0063-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Manuela Barona
- Institute of Child Health, 30 Guilford Street, London, WC1N 1EH UK
| | - Radha Kothari
- Institute of Child Health, 30 Guilford Street, London, WC1N 1EH UK
| | - David Skuse
- Institute of Child Health, 30 Guilford Street, London, WC1N 1EH UK
| | - Nadia Micali
- Institute of Child Health, 30 Guilford Street, London, WC1N 1EH UK ; Department of Psychiatry, Icahn Medical School at Mount Sinai; Mindich ChildHealth and Development Institute, Icahn Medical School at Mount Sinai, 31428 Madison Ave, New York, NY 10029 United States
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Guyatt AL, Heron J, Knight BLC, Golding J, Rai D. Digit ratio and autism spectrum disorders in the Avon Longitudinal Study of Parents and Children: a birth cohort study. BMJ Open 2015; 5:e007433. [PMID: 26307613 PMCID: PMC4550720 DOI: 10.1136/bmjopen-2014-007433] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 03/27/2015] [Accepted: 04/27/2015] [Indexed: 02/03/2023] Open
Abstract
OBJECTIVES To investigate whether second-to-fourth digit ratio (2D:4D), a measure commonly used as a proxy for fetal testosterone exposure, is associated with autism spectrum disorders (ASDs), as predicted by the extreme male brain theory of autism. DESIGN A birth cohort study. SETTING The Avon Longitudinal Study of Parents and Children (ALSPAC). PARTICIPANTS 6015 ALSPAC children with data on digit ratio, at least 1 outcome measure and information on potential confounding variables (parental occupational class, maternal education and age at digit ratio measurement). Digit ratio was measured by the photocopy and calliper method. OUTCOMES ASD diagnosis (cases were identified previously by record linkage or maternal report) and 4 measures that combine optimally within ALSPAC to predict ASD: the Children's Communication Checklist (coherence subscale), the Social and Communication Disorders Checklist, a repetitive behaviour measure, and the Emotionality, Activity and Sociability scale (sociability subscale). These measures were dichotomised, with approximately 10% defined as the 'risk' group. RESULTS Using logistic regression, we examined the association of 2D:4D with ASDs and 4 dichotomised ASD traits. Covariates were occupational class, maternal education and age at 2D:4D measurement. 2D:4D was not associated with ASDs in males (adjusted OR per 1 SD increase in mean 2D:4D, 0.88 (95% CI 0.65 to 1.21), p=0.435) or females (adjusted OR=1.36 (95% CI 0.81 to 2.28), p=0.245). Similar results were observed after adjustment for IQ. There was 1 weak association between reduced coherence and increased left 2D:4D in males, in the opposite direction to that predicted by the extreme male brain theory (adjusted OR=1.15 (95% CI 1.02 to 1.29), p=0.023). Given multiple comparisons, this is consistent with chance. CONCLUSIONS In this population-based study, there was no strong evidence of an association between 2D:4D and ASD diagnosis or traits, although the CIs were wide. These results are not consistent with the extreme male brain theory.
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Affiliation(s)
- Anna Louise Guyatt
- Centre for Academic Mental Health, School of Social and Community Medicine, University of Bristol, Bristol, UK
- MRC Integrative Epidemiology Unit, School of Social & Community Medicine, University of Bristol, Bristol, UK
| | - Jon Heron
- Centre for Academic Mental Health, School of Social and Community Medicine, University of Bristol, Bristol, UK
| | - Bernice Le Cornu Knight
- Centre for Academic Mental Health, School of Social and Community Medicine, University of Bristol, Bristol, UK
| | - Jean Golding
- Centre for Child and Adolescent Health, School of Social & Community Medicine, University of Bristol, Bristol, UK
| | - Dheeraj Rai
- Centre for Academic Mental Health, School of Social and Community Medicine, University of Bristol, Bristol, UK
- Avon and Wiltshire Partnership NHS Mental Health Trust, Bristol, UK
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Masuya Y, Okamoto Y, Inohara K, Matsumura Y, Fujioka T, Wada Y, Kosaka H. Sex-different abnormalities in the right second to fourth digit ratio in Japanese individuals with autism spectrum disorders. Mol Autism 2015; 6:34. [PMID: 26060570 PMCID: PMC4460687 DOI: 10.1186/s13229-015-0028-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 05/18/2015] [Indexed: 12/27/2022] Open
Abstract
Background The prevalence of autism spectrum disorders (ASDs) is higher in men than in women. The extreme male brain theory proposes that excessive prenatal testosterone activity could be a risk factor for ASDs. However, it is unclear whether prenatal sex hormone activity is a risk factor for women. The ratio of the length of the second to fourth digits (2D:4D) is considered to be a biomarker of the prenatal ratio of testosterone to estrogen. Therefore, this study compared the 2D:4D ratios of women with and without ASDs to determine if prenatal sex hormone activity could be a risk factor for ASDs in women. Methods The study included 35 Japanese men with ASDs, 17 Japanese women with ASDs, 59 typically developed (TD) Japanese men, and 57 TD Japanese women. We measured digit lengths and compared the 2D:4D ratios among the four groups. We also examined the relationship between the 2D:4D ratio and the autism-spectrum quotient score of each group. Results In our cohort, men with ASDs tended to have lower right-hand 2D:4D ratios relative to TD men. In contrast, the right 2D:4D ratios in women with ASDs were higher compared to those of TD women. No significant correlations were found between the 2D:4D ratios and the autism-spectrum quotient scores in any group. The higher right 2D:4D ratios in women could not be explained by age or full-scale intelligent quotients. This group difference was not found for the left 2D:4D or right–left 2D:4D ratios. Conclusions We found a reverse direction of abnormality in the right 2D:4D ratio for men and women with ASDs. It has been posited that high prenatal testosterone levels lead to a lower 2D:4D ratio. However, a recent animal study showed that testosterone injection to dam leads to a higher right 2D:4D ratio especially for female offspring, which might be mediated by abnormal adipose accumulation in the fingertip. Therefore, the present findings suggest that high prenatal testosterone could be a risk factor both for Japanese men and women with ASDs, elucidating one potential etiology of ASDs in women.
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Affiliation(s)
- Yasuhiro Masuya
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193 Japan
| | - Yuko Okamoto
- Research Center for Child Mental Development, University of Fukui, Fukui, 910-1193 Japan ; Division of Developmental Higher Brain Functions, Department of Child Development, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Fukui, 910-1193 Japan
| | - Keisuke Inohara
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193 Japan ; Department of Informatics, Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofu, 182-8585 Japan
| | - Yukiko Matsumura
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193 Japan
| | - Toru Fujioka
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193 Japan
| | - Yuji Wada
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193 Japan ; Research Center for Child Mental Development, University of Fukui, Fukui, 910-1193 Japan ; Division of Developmental Higher Brain Functions, Department of Child Development, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Fukui, 910-1193 Japan
| | - Hirotaka Kosaka
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193 Japan ; Research Center for Child Mental Development, University of Fukui, Fukui, 910-1193 Japan ; Division of Developmental Higher Brain Functions, Department of Child Development, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Fukui, 910-1193 Japan
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A critical review of the research on the extreme male brain theory and digit ratio (2D:4D). J Autism Dev Disord 2014; 43:2664-76. [PMID: 23575643 DOI: 10.1007/s10803-013-1819-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Boys are more likely than girls to be diagnosed with an autism spectrum disorder (ASD). The extreme male brain (EMB) theory of ASD suggests that fetal testosterone (FT) exposure may underlie sex differences in autistic traits. A link between the organizational effects of FT on the brain and ASD is often drawn based on research using digit ratio (2D:4D), a putative biomarker, without a full survey of the findings. This paper critically and quantitatively reviews the research on the relationship between 2D:4D and ASD as well as autism spectrum, empathizing, and systemizing measures in neurotypical populations. Overall, there is some support for the EMB theory in all four areas, particularly the 2D:4D-ASD relationship. Recommendations for future research are provided.
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Park IN, Yum HK, Lee SC, Oh JK, Kim TB. Second to fourth digit ratio: a predictor of adult lung function. Asian J Androl 2014; 16:140-5. [PMID: 24369148 PMCID: PMC3901873 DOI: 10.4103/1008-682x.122195] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Sex and sex hormones play a major role in lung physiology. It has been proposed that the ratio of the second to fourth digits (digit ratio) is correlated with fetal sex hormones. We therefore hypothesized that digit ratio might help predict lung function. We investigated the relationship between digit ratio and pulmonary function test (PFT) findings. A total of 245 South Korean patients (162 male, 83 female) aged from 34 to 90 years who were hospitalized for urological surgery were prospectively enrolled. Before administering the PFTs, the lengths of the second and fourth digits of the right hand were measured by a single investigator using a digital Vernier caliper. In males (n = 162), univariate and multivariate analysis using linear regression models showed that digit ratio was a significant predictive factor of forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) (FVC: r = 0.156, P = 0.047; FEV1: r = 0.160, P = 0.042). In male ever-smokers (n = 69), lung functions (FVC and FEV1) were correlated with smoking exposure rather than digit ratio. In female never-smokers (n = 83), lung functions (FEV1 and FEV1/FVC ratio) were positively correlated with digit ratio on univariate analysis (FEV1: r = 0.242, P = 0.027; FEV1/FVC ratio: r = 0.245, P = 0.026). Patients with lower digit ratios tend to have decreased lung function. These results suggest that digit ratio is a predictor of airway function.
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Affiliation(s)
| | | | | | | | - Tae Beom Kim
- Department of Urology, Gachon University Gil Hospital, Incheon, Korea
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Hönekopp J. Digit ratio 2D:4D in relation to autism spectrum disorders, empathizing, and systemizing: a quantitative review. Autism Res 2012; 5:221-30. [PMID: 22674640 DOI: 10.1002/aur.1230] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 03/22/2012] [Indexed: 01/29/2023]
Abstract
Prenatal testosterone (PT) effects have been proposed to increase systemizing (the drive to understand lawful input-output relationships), to decrease empathizing (the drive to understand others), and to cause autism via hypermasculinization of the brain. Digit ratio 2D:4D is a putative marker of PT effects in humans. An online study (n = 1896) into the relationship between the Reading the Mind in the Eyes Test (a widely used measure of empathizing) and self-measured 2D:4D in a nonclinical sample is reported. No evidence for a link between empathizing and 2D:4D in either females or males emerged. Further, three meta-analyses are presented that look into the relationships of 2D:4D with autism spectrum disorder (ASD), systemizing, and empathizing. 2D:4D was substantially lower (more masculine) in ASD-affected individuals than in normal controls (d = -0.58, P < 0.001). However, 2D:4D was found to be virtually unrelated to systemizing and empathizing in normal adults. The results support the idea that high PT is a risk factor for autism, but they challenge the view that PT substantially contributes to sex differences in systemizing and empathizing. Possibly, this pattern reflects an interaction effect, whereby PT drives ASD characteristic changes only in brains with a specific damage.
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Affiliation(s)
- Johannes Hönekopp
- Department of Psychology, Northumbria University, Newcastle upon Tyne, UK.
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Gamliel M, Ebstein R, Yirmiya N, Mankuta D. Minor Fetal Sonographic Findings in Autism Spectrum Disorder. Obstet Gynecol Surv 2012; 67:176-86. [DOI: 10.1097/ogx.0b013e31824bb5d6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Abstract
Autism spectrum conditions have been hypothesized to be an exaggeration of normal male low-empathizing and high-systemizing behaviors. We tested this hypothesis at the molecular level by performing comprehensive multi-analyte profiling of blood serum from adult subjects with Asperger's syndrome (AS) compared with controls. This led to identification of distinct sex-specific biomarker fingerprints for male and female subjects. Males with AS showed altered levels of 24 biomarkers including increased levels of cytokines and other inflammatory molecules. Multivariate statistical classification of males using this panel of 24 biomarkers revealed a marked separation between AS and controls with a sensitivity of 0.86 and specificity of 0.88. Testing this same panel in females did not result in a separation between the AS and control groups. In contrast, AS females showed altered levels of 17 biomarkers including growth factors and hormones such as androgens, growth hormone and insulin-related molecules. Classification of females using this biomarker panel resulted in a separation between AS and controls with sensitivities and specificities of 0.96 and 0.83, respectively, and testing this same panel in the male group did not result in a separation between the AS and control groups. The finding of elevated testosterone in AS females confirmed predictions from the 'extreme male brain' and androgen theories of autism spectrum conditions. We conclude that to understand the etiology and development of autism spectrum conditions, stratification by sex is essential.
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Second to fourth digit ratio: a predictor of adult penile length. Asian J Androl 2011; 13:710-4. [PMID: 21725330 DOI: 10.1038/aja.2011.75] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The second to fourth digit ratio (2D:4D) has been proposed as a putative biomarker for prenatal testosterone and covaries with the sensitivity of the androgen receptor (AR). Both prenatal testosterone and the AR play a central role in penile growth. In this study, we investigated the relationship between digit ratio and penile length. Korean men who were hospitalized for urological surgery at a single tertiary academic centre were examined in this study, and 144 men aged 20 years or older who gave informed consent were prospectively enrolled. Right-hand second- and fourth-digit lengths were measured by a single investigator prior to measurement of penile length. Under anaesthesia, flaccid and stretched penile lengths were measured by another investigator who did not measure nor have any the information regarding the digit lengths. Univariate and multivariate analysis using linear regression models showed that only height was a significant predictive factor for flaccid penile length (univariate analysis: r=0.185, P=0.026; multivariate analysis: r=0.172, P=0.038) and that only digit ratio was a significant predictive factor for stretched penile length (univariate analysis:r=-0.216, P=0.009; multivariate analysis: r=-0.201, P=0.024; stretched penile length=-9.201×digit ratio + 20.577). Based on this evidence, we suggest that the digit ratio can predict adult penile size and that the effects of prenatal testosterone may in part explain the differences in adult penile length.
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