1
|
Veerappa AM, Saldanha M, Padakannaya P, Ramachandra NB. Genome-wide copy number scan identifies disruption of PCDH11X in developmental dyslexia. Am J Med Genet B Neuropsychiatr Genet 2013; 162B:889-97. [PMID: 24591081 DOI: 10.1002/ajmg.b.32199] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 08/13/2013] [Indexed: 02/02/2023]
Abstract
Developmental dyslexia (DD) is a complex heritable disorder with unexpected difficulty in learning to read and spell despite adequate intelligence, education, environment, and normal senses. We performed a whole genome copy number variations (CNV) scan on 11 dyslexic families consisting of 14 dyslexic subjects and 24 non dyslexic members using 1.8 million combined SNP and CNV markers. We found CNVs affecting protocadherin genes in six dyslexics from three families, while none among the non-dyslexic control members showed any CNV in protocadherins. We identified duplications in five cases and a deletion in one case in Xq21.3 region bearing PCDH11X. Unequal recombination between the X-transposed region (XTR) of Yp11.2 and the X chromosome might be causing these structural changes. PCDH11X, expressed in brain is implicated in cell-cell communication, verbal ability, cerebral asymmetry, and dendritic synaptic plasticity, may be regarded as a new candidate gene for dyslexia.
Collapse
Affiliation(s)
- Avinash M Veerappa
- Genomics Laboratory, Department of Studies in Zoology, University of Mysore, Manasagangotri, Mysore, Karnataka, India
| | | | | | | |
Collapse
|
2
|
Melchior L, Bertelsen B, Debes NM, Groth C, Skov L, Mikkelsen JD, Brøndum-Nielsen K, Tümer Z. Microduplication of 15q13.3 and Xq21.31 in a family with Tourette syndrome and comorbidities. Am J Med Genet B Neuropsychiatr Genet 2013; 162B:825-31. [PMID: 23894120 DOI: 10.1002/ajmg.b.32186] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 06/26/2013] [Indexed: 12/31/2022]
Abstract
Tourette syndrome (TS) is a childhood onset neurodevelopmental disorder. Although it is widely accepted that genetic factors play a significant role in TS pathogenesis the etiology of this disorder is largely unknown. Identification of rare copy number variations (CNVs) as susceptibility factors in several neuropsychiatric disorders such as attention deficit-hyperactivity disorder (ADHD), autism and schizophrenia, suggests involvement of these rare structural changes also in TS etiology. In a male patient with TS, ADHD, and OCD (obsessive compulsive disorder) we identified two microduplications (at 15q13.3 and Xq21.31) inherited from a mother with subclinical ADHD. The 15q duplication included the CHRNA7 gene; while two genes, PABPC5 and PCDH11X, were within the Xq duplication. The Xq21.31 duplication was present in three brothers with TS including the proband, but not in an unaffected brother, whereas the 15q duplication was present only in the proband and his mother. The structural variations observed in this family may contribute to the observed symptoms, but further studies are necessary to investigate the possible involvement of the described variations in the TS etiology.
Collapse
Affiliation(s)
- Linea Melchior
- Applied Human Molecular Genetics, Kennedy Center, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark
| | | | | | | | | | | | | | | |
Collapse
|
3
|
Veerappa AM, Padakannaya P, Ramachandra NB. Copy number variation-based polymorphism in a new pseudoautosomal region 3 (PAR3) of a human X-chromosome-transposed region (XTR) in the Y chromosome. Funct Integr Genomics 2013; 13:285-93. [PMID: 23708688 DOI: 10.1007/s10142-013-0323-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 03/31/2013] [Accepted: 04/01/2013] [Indexed: 11/26/2022]
Abstract
A 3.5-Mb region of the X chromosome underwent duplication and transposition to the Y chromosome ~5-6 Mya. This X-transposed-region (XTR) originated at Xq21.3 and was inserted at Yp11.2. The two locations have 98.78 % homology and a high concentration of tandem repeats. In whole-genome scans of ten large families with dyslexic members, we identified transposed blocks comprising >102 kb of the Yp11.2 region in its homologous region at Xq21.3 in three females from three different families. Although recombination is known to be limited only to the pseudoautosomal regions (PARs) of the X and Y chromosomes, we report allelic unequal recombination between the XTR region Yp11.2 and Xq21.3, indicating the presence of a new PAR, which we named PAR3. This PAR3 region was also found in 2 % of the general population. An additional layer of justification could be provided from six other dyslexic cases which harbored duplications and deletions in the same Xq21.3 and Yp11.2 regions through allelic unequal recombination.
Collapse
Affiliation(s)
- Avinash M Veerappa
- Genomics Laboratory, DOS in Zoology, University of Mysore, Mysore-06, Karnataka, India
| | | | | |
Collapse
|
4
|
Crow TJ. Schizophrenia as variation in the sapiens-specific epigenetic instruction to the embryo. Clin Genet 2012; 81:319-24. [DOI: 10.1111/j.1399-0004.2012.01830.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
|
5
|
All sex differences in cognitive ability may be explained by an X-Y homologous gene determining degrees of cerebral asymmetry. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00042436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractMale superiority in mathematical ability (along with female superiority in verbal fluency) may reflect the operation of an X-Y homologous gene (the right-shift-factor) influencing the relative rates of development of the cerebral hemispheres. Alleles at the locus on the Y chromosome will be selected at a later mean age than alleles on the X, and only by females.
Collapse
|
6
|
Abstract
AbstractGeary is highly selective in his use of the literature on gender differences. His assumption of consistent female inferiority in mathematics is not necessarily supported by the facts.
Collapse
|
7
|
Abstract
AbstractAlthough Geary's partitioning of mathematical abilities into those that are biologically primary and secondary is an advance over most sociobiological theories of cognitive sex differences, it remains untestable and ignores the spatial nature of women's traditional work. An alternative model based on underlying cognitive processes offers other advantages.
Collapse
|
8
|
Abstract
AbstractThis commentary focuses on one of the many issues raised in Geary's target article: the importance of gender differences in spatial ability to gender differences in mathematics. I argue that the evidence for the central role of spatial ability in mathematical ability, or in gender differences in it, is tenuous at best.
Collapse
|
9
|
Abstract
AbstractSpatial visualization as a key variable in sex-related differences in mathematical problem solving and spatial aspects of geometry is traced to the 1960s. More recent relevant data are presented. The variability debate is traced to the latter part of the nineteenth century and an explanation for it is suggested. An idea is presented for further research to clarify sex-related brain laterality differences in solving spatial problems.
Collapse
|
10
|
Abstract
AbstractThe principles of sexual selection were used as an organizing framework for interpreting cross-national patterns of sex differences in mathematical abilities. Cross-national studies suggest that there are no sex differences in biologically primary mathematical abilities, that is, for those mathematical abilities that are found in all cultures as well as in nonhuman primates, and show moderate heritability estimates. Sex differences in several biologically secondary mathematical domains (i.e., those that emerge primarily in school) are found throughout the industrialized world. In particular, males consistently outperform females in the solving of mathematical word problems and geometry. Sexual selection and any associated proximate mechanisms (e.g., sex hormones) influence these sex differences in mathematical performance indirectly. First, sexual selection resulted in greater elaboration in males than in females of the neurocognitive systems that support navigation in three-dimensional space. Knowledge implicit in these systems reflects an understanding of basic Euclidean geometry, and may thus be one source of the male advantage in geometry. Males also use more readily than females these spatial systems in problem-solving situations, which provides them with an advantage in solving word problems and geometry. In addition, sex differences in social styles and interests, which also appear to be related in part to sexual selection, result in sex differences in engagement iii mathematics-related activities, thus further increasing the male advantage in certain mathematical domains. A model that integrates these biological influences with sociocultural influences on the sex differences in mathematical performance is presented in this article.
Collapse
|
11
|
Priddle TH, Crow TJ. The protocadherin 11X/Y gene pair as a putative determinant of cerebral dominance in Homo sapiens. FUTURE NEUROLOGY 2009. [DOI: 10.2217/fnl.09.23] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The cerebral torque, a bias from right frontal to left occipital across the anterior–posterior axis is arguably the defining feature of the human brain, and the foundation for language. What is its genetic basis? Handedness and anatomical data suggest that this torque is specific to humans relative to the extant great apes. Asymmetry deficits associated with sex chromosome aneuploidies implicate loci on both the X and Y chromosomes. A block from the Xq21.3 band was duplicated to the Y chromosome 6 million years ago (close to, and a possible cause of the chimpanzee/hominin separation) containing the human-specific gene pair PCDH11X/Y. PCDH11Y has been subject to positive selection through hominin evolution including 18 amino-acid changes to the longest isoform of the protein. The PCDH11X protein has been subject to five substitutions including two cysteines in the ectodomain. The gene pair can account for sex differences, for example, in cerebral asymmetry and language.
Collapse
Affiliation(s)
- Tom H Priddle
- University of Oxford, Warneford Hospital, Oxford, OX3 7JX, UK
| | | |
Collapse
|
12
|
Karcanias AC, Ichimura K, Mitchell MJ, Sargent CA, Affara NA. Analysis of sex chromosome abnormalities using X and Y chromosome DNA tiling path arrays. J Med Genet 2007; 44:429-36. [PMID: 17327287 PMCID: PMC2598010 DOI: 10.1136/jmg.2006.047852] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Array comparative genomic hybridisation is a powerful tool for the detection of copy number changes in the genome. METHODS A human X and Y chromosome tiling path array was developed for the analysis of sex chromosome aberrations. RESULTS Normal X and Y chromosome profiles were established by analysis with DNA from normal fertile males and females. Detection of infertile males with known Y deletions confirmed the competence of the array to detect AZFa, AZFb and AZFc deletions and to distinguish between different AZFc lesions. Examples of terminal and interstitial deletions of Xp (previously characterised through cytogenetic and microsatellite analysis) have been assessed using the arrays, thus both confirming and refining the established deletion breakpoints. Breakpoints in iso-Yq, iso-Yp and X-Y translocation chromosomes and X-Y interchanges in XX males are also amenable to analysis. DISCUSSION The resolution of the tiling path clone set used allows breakpoints to be placed within 100-200 kb, permitting more precise genotype/phenotype correlations. These data indicate that the combined X and Y tiling path arrays provide an effective tool for the investigation and diagnosis of sex chromosome copy number aberrations and rearrangements.
Collapse
Affiliation(s)
- A C Karcanias
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | | | | | | | | |
Collapse
|
13
|
Williams NA, Close JP, Giouzeli M, Crow TJ. Accelerated evolution of Protocadherin11X/Y: a candidate gene-pair for cerebral asymmetry and language. Am J Med Genet B Neuropsychiatr Genet 2006; 141B:623-33. [PMID: 16874762 DOI: 10.1002/ajmg.b.30357] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
It has been argued that cerebral asymmetry (the "torque") is the characteristic that defines the human brain and that morphological findings in psychosis are consistent with a deviation in this sex-dependent dimension of brain growth. Evidence from sex chromosome aneuploidies and an association within families between sex and handedness is consistent with the presence of a determinant of cerebral asymmetry (a possible correlate of language) on the X and the Y chromosomes. During hominid evolution a 3.5 Mb translocation occurred from the ancestral X chromosome to the Y chromosome, resulting in duplication of the Protocadherin11X gene, such that it is represented on the X and Y chromosomes in man, whereas there is a single X-linked gene in other mammals. We re-date the duplicative translocation to 6 million years ago, that is, close to the chimpanzee-hominid bifurcation. Sequence comparisons with the chimpanzee, bonobo, gorilla, and orangutan indicate that in contrast to earlier purifying selection there has been accelerated change in the Protocadherin11X ectodomain as well as the Protocadherin11Y sequence in the hominid lineage since the duplication. The evolutionary sequence of events together with the prior case for an X-Y homologous gene suggests that this gene-pair is a candidate for the evolution of hominid-specific characteristics including the sexual dimorphism of cerebral asymmetry, a putative correlate of language.
Collapse
Affiliation(s)
- Nic A Williams
- Prince of Wales International Centre for SANE Research, University of Oxford, Warneford Hospital, Oxford, United Kingdom
| | | | | | | |
Collapse
|
14
|
Wilson ND, Ross LJN, Crow TJ, Volpi EV. PCDH11 is X/Y homologous in Homo sapiens but not in Gorilla gorilla and Pan troglodytes. Cytogenet Genome Res 2006; 114:137-9. [PMID: 16825765 DOI: 10.1159/000093329] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Accepted: 01/09/2006] [Indexed: 11/19/2022] Open
Abstract
Protocadherin X (PCDHX) and Protocadherin Y (PCDHY) are cell-surface adhesion molecules expressed predominantly in brain. The human PCDH11X/Y gene pair is located in the non-pseudoautosomal X-Y homologous region (Xq21.3/Yp11.2). The possible existence of PCDH11 gene dosage differences between human and non-human primates is of evolutionary significance with respect to species differences and escape from X inactivation, and has been repeatedly debated. Previous investigations on the X/Y homologous status of PCDH11 and adjacent sequences in non-human primates have highlighted the complexity of the molecular pattern and evolutionary history of this genomic region. This paper provides for the first time direct evidence for the absence of the PCDH11 genefrom the Y chromosome of chimpanzee (Pan troglodytes) as well as gorilla (Gorilla gorilla). By confirmingthe suspected lack of X-Y homologous status for PCDH11 in non-human primates, our results reinforce the hypothesis of a hominid-specific role for this gene in brain development.
Collapse
Affiliation(s)
- N D Wilson
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | | | | | | |
Collapse
|
15
|
Giouzeli M, Williams NA, Lonie LJ, DeLisi LE, Crow TJ. ProtocadherinX/Y, a candidate gene-pair for schizophrenia and schizoaffective disorder: a DHPLC investigation of genomic sequence. Am J Med Genet B Neuropsychiatr Genet 2004; 129B:1-9. [PMID: 15274028 DOI: 10.1002/ajmg.b.30036] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Protocadherin X and Protocadherin Y (PCDHX and PCDHY) are cell-surface adhesion molecules expressed predominantly in the brain. The PCDHX/Y gene-pair was generated by an X-Y translocation approximately 3 million years ago (MYA) that gave rise to the Homo sapiens-specific region of Xq21.3 and Yp11.2 homology. Genes within this region are expected to code for sexually dimorphic human characteristics, including, for example, cerebral asymmetry a dimension of variation that has been suggested is relevant to psychosis. We examined differences in patients with schizophrenic or schizoaffective psychosis in the genomic sequence of PCDHX and PCDHY in coding and adjacent intronic sequences using denaturing high performance liquid chromatography (DHPLC). Three coding variants were detected in PCDHX and two in PCDHY. However, neither the coding variants nor the intronic polymorphisms could be related to psychosis within families. Low sequence variation suggests selective pressure against sequence change in modern humans in contrast to the structural chromosomal and sequence changes including fixed X-Y differences that occurred in this region earlier in hominid evolution. Our findings exclude sequence variation in PCDHX/Y as relevant to the aetiology of psychosis. However, we note the unusual status of this region with respect to X-inactivation. Further investigation of the epigenetic control of PCDHX/Y in relation to psychosis is warranted.
Collapse
Affiliation(s)
- Maria Giouzeli
- Department of Psychiatry, POWIC SANE Research Centre, University of Oxford, Warneford Hospital, Oxford, United Kingdom.
| | | | | | | | | |
Collapse
|
16
|
Balaresque P, Toupance B, Heyer E, Crouau-Roy B. Evolutionary dynamics of duplicated microsatellites shared by sex chromosomes. J Mol Evol 2004; 57 Suppl 1:S128-37. [PMID: 15008409 DOI: 10.1007/s00239-003-0018-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Segmental duplications on sex chromosomes constitute an important proportion of recent duplications (approximately 30%). Among those, the evolution of duplicated noncoding DNA is still poorly investigated. We focus our work on repeated DNA sequences extensively used in population genetics and evolution: microsatellites. Six duplicated (CA), microsatellite loci, located on the homologous region of human sex chromosomes, were studied at the intraspecific level in Homo sapiens and by an orthologous comparison in eight primate species. At the intraspecific level, we evaluated the congruence in paralogous divergence between the flanking sequences of the six microsatellites and the approximately 2.2-kb surrounding sequences and observed that both phylogenies are congruent. At the interspecific level (8 species of primates: 54 individuals), we analyzed the sequence polymorphism and divergence of each orthologous locus for both the flanking sequence and the microsatellite. The results showed a lower divergence of flanking sequences than expected in noncoding DNA and a relative stability of the first nucleotides close to the microsatellite. The location of each CAIII locus in a Low Copy Repeated element containing duplicated VCX/Y genes (approximately 1 kb) suggested that direct or indirect selection could explain these results. Moreover, the substitution rates in the flanking sequences and in the microsatellites were correlated. Thus, the evolutionary dynamics of microsatellites seems closely linked to the variation of spontaneous mutations in the surrounding regions.
Collapse
Affiliation(s)
- Patricia Balaresque
- Laboratoire Evolution et Diversité Biologique, UMR 5174 Bat. IV R3, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 4, France.
| | | | | | | |
Collapse
|
17
|
Crow TJ. Handedness, language lateralisation and anatomical asymmetry: relevance of protocadherin XY to hominid speciation and the aetiology of psychosis. Point of view. Br J Psychiatry 2002; 181:295-7. [PMID: 12356655 DOI: 10.1192/bjp.181.4.295] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- T J Crow
- POWIC, Department of Psychiatry, Warneford Hospital, Oxford OX3 7JX, UK
| |
Collapse
|
18
|
Norlander T. Conceptual Convergence in Creativity: Incubation and Brain Disease State. CREATIVITY RESEARCH JOURNAL 2001. [DOI: 10.1207/s15326934crj1334_10] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
|
19
|
Corballis MC. Is the handedness gene on the X chromosome? Comment on Jones and Martin (2000). Psychol Rev 2001; 108:805-10; discussion 811-3. [PMID: 11699118 DOI: 10.1037/0033-295x.108.4.805] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
G. V. Jones and M. Martin (2000) argued, contrary to M. C. Corballis (1997), that a gene for handedness might plausibly be located in homologous, noncombining regions of the X and Y chromosomes. The specific model they proposed is unlikely to be correct, but a case can be made for an X-linked gene that has no homologue on the Y chromosome and that is subjected to X-inactivation in females. An X-linked gene predicts no overall sex difference in the incidence of left-handedness; the slight preponderance of left-handers among males might then be attributed to a higher incidence of pathologically induced left-handedness.
Collapse
Affiliation(s)
- M C Corballis
- Department of Psychology, University of Auckland, Private Bag 92019, Auckland, New Zealand.
| |
Collapse
|
20
|
Blanco P, Sargent CA, Boucher CA, Howell G, Ross M, Affara NA. A novel poly(A)-binding protein gene (PABPC5) maps to an X-specific subinterval in the Xq21.3/Yp11.2 homology block of the human sex chromosomes. Genomics 2001; 74:1-11. [PMID: 11374897 DOI: 10.1006/geno.2001.6530] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The gene-poor human-specific Xq21.3/Yp11.2 block of homology exhibits 99% nucleotide identity, with the exception of an internal X-specific region containing the marker DXS214. This paper describes the characterization of a novel gene (PABPC5) from this X-specific subinterval that belongs to the poly(A)-binding protein gene family. The genomic structure of PABPC5 covers 4061 bp of an uninterrupted open reading frame (ORF) and a 5'UTR spanning across two exons and associated with a CpG island; the potential 382-amino-acid protein contains four RNA recognition motif domains. PABPC5 has 73% nucleotide identity with PABPC4 over 1801 bp of the ORF. At the protein level, 60% identity and 75% similarity are obtained in the comparison with human PABPC4, as well as human, mouse, and Xenopus PABPC1. RT-PCR indicates that PABPC5 is expressed in fetal brain and in a range of adult tissues. Conservation of the PABPC5 ORF and genomic structure is shown in primates and rodents. The close proximity of this gene to translocation breakpoints associated with premature ovarian failure makes it a potential candidate for this condition.
Collapse
Affiliation(s)
- P Blanco
- Human Molecular Genetics Group, Division of Cellular and Molecular Pathology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, United Kingdom
| | | | | | | | | | | |
Collapse
|
21
|
Sargent CA, Boucher CA, Blanco P, Chalmers IJ, Highet L, Hall N, Ross N, Crow T, Affara NA. Characterization of the human Xq21.3/Yp11 homology block and conservation of organization in primates. Genomics 2001; 73:77-85. [PMID: 11352568 DOI: 10.1006/geno.2000.6491] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Xq21.3/Yp11 homology block on the human sex chromosomes represents a recent addition to the Y chromosome through a transposition event. It is believed that this transfer of material occurred after the divergence of the hominid lineage from other great apes. In this paper we investigate the structure and evolution of the block through fluorescence in situ hybridisation, contig assembly, the polymerase chain reaction, exon trapping, sequence comparison, and annotation of sequence data. The overall structure is well conserved between the human X chromosome and the Y chromosome as well as between the X chromosomes from different primates. Although the sequence data reveal a high level of nucleotide sequence identity for the human X and Y, there are regions of significant divergence, such as that around the marker DXS214. These are presumably the consequence of multiple rearrangements during evolution and are of particular importance with respect to the potential gene content in this segment of the interval.
Collapse
Affiliation(s)
- C A Sargent
- Human Molecular Genetics Group, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, United Kingdom
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Makrinou E, Fox M, Lovett M, Haworth K, Cameron JM, Taylor K, Edwards YH. TTY2: a multicopy Y-linked gene family. Genome Res 2001; 11:935-45. [PMID: 11381023 PMCID: PMC311066 DOI: 10.1101/gr.175901] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Genes involved in human male sex determination and spermatogenesis are likely to be located on the Y chromosome. In an effort to identify Y-linked, testis-expressed genes, a cDNA selection library was generated by selecting testis cDNA with Y-cosmid clones. Resultant clones containing repetitive or vector material were eliminated, and 79 of the remaining clones were sequenced. Nineteen cDNAs showed homology with the TTY2 gene, and indicated that TTY2 is part of a large gene family. Screening of a panel of Y-linked cosmids revealed that the TTY2 gene family includes at least 26 members organized in 14 subfamilies. Further investigation revealed that TTY2 genes are arranged in tandemly arrayed clusters on both arms of the Y chromosome, and each gene comprises a series of tandemly arranged repeats. RT-PCR studies for two of these genes revealed that they are expressed in adult and fetal testis, as well as in the adult kidney. None of the genes investigated in detail contain an open reading frame. We conclude that the TTY2 gene family is composed of multiple copies, some of which may function as noncoding RNA transcripts and some may be pseudogenes.
Collapse
Affiliation(s)
- E Makrinou
- MRC Human Biochemical Genetics Unit, University College London, Wolfson House, London NW1 2HE, UK
| | | | | | | | | | | | | |
Collapse
|
23
|
Abstract
It was suggested by Ronald Fisher in 1931 that genes involved in benefit to the male (including spermatogenesis genes) would accumulate on the Y chromosome. The analysis of mouse Y chromosome deletions and the discovery of microdeletions of the human Y chromosome associated with diverse defective spermatogenic phenotypes has revealed the presence of intervals containing one or more genes controlling male germ cell differentiation. These intervals have been mapped, cloned and examined in detail for functional genes. This review discusses the genes mapping to critical spermatogenesis intervals and the evidence indicating which are the most likely candidates underlying Y-linked male infertility.
Collapse
Affiliation(s)
- N A Affara
- Department of Pathology, University of Cambridge, UK
| | | |
Collapse
|
24
|
Kim HS, Hyun BH, Choi JY, Crow TJ. Phylogenetic analysis of a retroposon family as represented on the human X chromosome. Genes Genet Syst 2000; 75:197-202. [PMID: 11126568 DOI: 10.1266/ggs.75.197] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
SINE-R elements constitute a class of retroposons derived from the long terminal repeat (LTR) of the human endogenous retrovirus HERV-K family that are present in hominoid primates and active in the human genome. In an investigation of the X chromosome, we identified twenty-five SINE-R elements with between 89.6 and 97.7% homology with the SINE-R.C2 element that is human specific, originally identified in the gene for the C2 component of complement. SINE-R.C2 and a sequence HS307 that we previously identified in a region of Xq21.3 that has a recently created homology with a 4 Mb block in Yp11.2 are amongst the group of elements that have diverged furthest from the parent HERV-K10 sequence. The sequence on the X chromosome resemble those that we previously described on chromosomes 7 and 17 and the Y chromosome, with a similar range of variation. Phylogenetic analysis from the retroposon family including those of African great apes using the neighbor-joining method suggests that the SINE-R retroposon family have evolved independently during primate evolution. Further investigation of SINE-R elements on the sex chromosomes, particularly in recently created regions of X-Y homology, may cast light on the timing of the retroposition process and its possible relevance to recent evolutionary change.
Collapse
Affiliation(s)
- H S Kim
- Division of Biological Sciences, College of Natural Sciences, Pusan National University, Pusan, Korea.
| | | | | | | |
Collapse
|
25
|
DeLisi LE, Shaw S, Sherrington R, Nanthakumar B, Shields G, Smith AB, Wellman N, Larach VW, Loftus J, Razi K, Stewart J, Comazzi M, Vita A, De Hert M, Crow TJ. Failure to establish linkage on the X chromosome in 301 families with schizophrenia or schizoaffective disorder. AMERICAN JOURNAL OF MEDICAL GENETICS 2000; 96:335-41. [PMID: 10898911 DOI: 10.1002/1096-8628(20000612)96:3<335::aid-ajmg20>3.0.co;2-e] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The hypothesis that a gene for susceptibility to psychosis (specifically in the X-Y homologous class) is located on the sex chromosomes has been proposed. Such a gene would account for the excess of sex chromosome anomalous males and females in populations of patients with psychosis, a tendency towards concordance by sex within families, and sex differences associated with psychosis and its underlying brain pathology. In earlier studies we observed small positive LOD scores in Xp11, and in a more recent and larger cohort of 178 sibling pairs, a peak multipoint nonparametric LOD score of 1. 55 at the locus DXS8032 in Xq21. The present study with a new set of markers extended the cohort to 301 ill sibling pairs and their parents. Despite the increase in sample size, the LOD score did not increase. A peak NPL of 1.55 was observed at the locus DXS1068 in proximal Xp, a region remote from the previous report. Separating families into those who were more likely to have X chromosome inheritance (maternal with no male to male transmission) did not yield stronger findings. In spite of the evidence that psychosis is related to a sex-dependent dimension of cerebral asymmetry, it is concluded that no consistent linkage of schizophrenia to the X chromosome can be demonstrated. In the context of the general failure of replication of linkage in psychosis, the possibility that the genetic predisposition to psychosis is contributed to by epigenetic modification rather than variations in the nucleotide sequence has to be considered.
Collapse
Affiliation(s)
- L E DeLisi
- Department of Psychiatry, SUNY at Stony Brook, NY 11794, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Mitchell MJ. Spermatogenesis and the mouse Y chromosome: specialisation out of decay. Results Probl Cell Differ 2000; 28:233-70. [PMID: 10626301 DOI: 10.1007/978-3-540-48461-5_10] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- M J Mitchell
- Inserm U.491, Faculté de médecine, Marseille, France
| |
Collapse
|
27
|
Vacca M, Matarazzo MR, Jones J, Spalluto C, Archidiacono N, Ma P, Rocchi M, D'Urso M, Chen EY, D'Esposito M, Mumm S. Evolution of the X-specific block embedded in the human Xq21.3/Yp11.1 homology region. Genomics 1999; 62:293-6. [PMID: 10610725 DOI: 10.1006/geno.1999.5996] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The region Xq21.3/Yp11.1 represents the largest segment of homology between the sex chromosomes in humans, though no recombination occurs in male meiosis. It presumably arose as a transposition from the X to the Y chromosome; the present-day organization in the latter chromosome indicates a paracentric inversion that disrupted its continuity. Moreover, an X-specific block (defined by the marker DXS214) is embedded in the region. Previously, no hypotheses about the length, origin, or evolution of this X-specific segment have been proposed. Here we report on the refinement of the size and the sequence of the distal boundary of the X-specific block. Furthermore, we have tracked by FISH experiments the evolution of this region in primates. This further clarifies the multistep mechanism of origin for the XY homology region, by demonstrating that the X-specific block was deleted from the Y chromosome after the initial transfer from the X chromosome.
Collapse
Affiliation(s)
- M Vacca
- International Institute of Genetics and Biophysics, CNR, Naples, Italy
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Crow TJ. Commentary on Annett, Yeo et al., Klar, Saugstad and Orr: cerebral asymmetry, language and psychosis--the case for a Homo sapiens-specific sex-linked gene for brain growth. Schizophr Res 1999; 39:219-31. [PMID: 10507514 DOI: 10.1016/s0920-9964(99)00076-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Annett, Yeo et al. and Klar have each proposed theories that relate the genetics of cerebral lateralization to predisposition to psychosis. These theories are considered in relation to the central paradox that psychosis is associated with a substantial biological disadvantage. Annett's heterozygote advantage hypothesis critically identified lateralization as a major determinant of ability, but it appears that what is inherited is degrees (as suggested by Yeo et al.) rather than (or as well as) direction of lateralization. Relative hand skill has been shown (Crow, T.J., Crow, L.R., Done, D.J., Leask, S.J., 1998. Relative hand skill predicts academic ability: global deficits at the point of hemispheric indecision. Neuropsychologia 36, 1275-1282.) to be a powerful predictor (interacting with sex) of academic ability but the greatest region of vulnerability (that includes reading disability and predisposition to psychosis) is close to the point of equal hand skill ('hemispheric indecision'). In contrast with Annett's single locus, Yeo's polygenic and Klar's strand-segregation hypotheses, each of which postulates an autosomal locus or loci, the hypothesis of a single gene for asymmetry located in a sex-specific region of homology on both X and Y chromosomes can account for sex differences, as observed in age of onset, and premorbid precursors of psychosis, as well as differences in the general population in relation to degrees of hand skill, verbal ability and cerebral asymmetry. The evolutionarily recent transposition to, and subsequent paracentric inversion in, the Y chromosome short arm of a 4-Mb block from Xq21.3 (the proximal long arm of the X) are candidates for speciation events in the lineage that led to Homo sapiens. A gene associated with a range of variation (that may be due to a high mutation site, or perhaps to epigenetic modification) on the Y that overlaps with, but differs quantitatively from, that on the X may explain the sex differences associated with psychosis, and may be relevant to its persistence. Such a gene could be the principal determinant in Man of the rate of brain growth, as suggested by Saugstad and by the findings of a recent study of adolescent onset psychosis (James, A., Crow, T.J., Renowden, S., Wardell, M., Smith, D.M., Anslow, P., in press. Is the course of brain development in schizophrenia delayed? Evidence from onsets in adolescence. Schizophr. Res.).
Collapse
Affiliation(s)
- T J Crow
- POWIC, University Department of Psychiatry, Warneford Hospital, Oxford, UK.
| |
Collapse
|
29
|
Kim HS, Wadekar RV, Takenaka O, Winstanley C, Mitsunaga F, Kageyama T, Hyun BH, Crow TJ. SINE-R.C2 (a Homo sapiens specific retroposon) is homologous to CDNA from postmortem brain in schizophrenia and to two loci in the Xq21.3/Yp block linked to handedness and psychosis. ACTA ACUST UNITED AC 1999. [DOI: 10.1002/(sici)1096-8628(19991015)88:5<560::aid-ajmg23>3.0.co;2-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
30
|
Kim HS, Crow TJ. Presence and phylogenetic analysis of HERV-K LTR on human X and Y chromosomes: evidence for recent proliferation. Genes Genet Syst 1999; 74:267-70. [PMID: 10734608 DOI: 10.1266/ggs.74.267] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The K group of human endogenous retroviruses (HERV-K) has been suggested to have a role in disease and has recently been shown to include long terminal repeat (LTR) elements that are human specific. Here we investigated the presence of HERV-K LTRs on the human X and Y chromosomes with the use of PCR on a monochromosomal somatic cell hybrid DNA panel. We report twelve such sequences on the X chromosome and ten sequences on the Y chromosome. Phylogenetic analysis reveals that clones X2, 4, 5, 6, 7, 11, 15 from the X chromosome and clones Y4, 5, 7, 10 from the Y chromosome are closely related to the human-specific members of Medstrand and Mager's cluster 9. The sequence of clone Y7 from the Y chromosome is identical with human-specific HERV-K LTR element (AC002350) from chromosome 12q24. The findings suggest recent proliferation and transposition of HERV-K LTR elements on these chromosomes. Such events may have contributed to structural change and genetic variation in the human genome. We draw attention to evolutionarily recent changes in homologies between X and Y chromosomes as a method of further investigating such transpositions.
Collapse
Affiliation(s)
- H S Kim
- Department of Psychiatry, Warneford Hospital, University of Oxford, United Kingdom
| | | |
Collapse
|
31
|
The case for an Xq21.3/Yp homologous locus in the evolution of language and the origins of psychosis. Acta Neuropsychiatr 1999; 11:54-6. [PMID: 26976253 DOI: 10.1017/s0924270800036152] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The distribution of schizophrenia within populations bears upon the genetic nature of the disorder. From the World Health Organization Ten-Country Study of incidence Jablensky et al concluded that: Schizophrenic illnesses are ubiquitous, appear with similar incidence in different cultures and have clinical features that are more remarkable by their similarity across cultures than by their difference. The WHO study included populations in Japan, India and Europe that have been separated for tens of thousands of years. Moreover illnesses with essentially the same characteristics are commonplace in the Australian aboriginal population that separated from other human populations 50,000 years ago.
Collapse
|
32
|
Mazeyrat S, Saut N, Sargent CA, Grimmond S, Longepied G, Ehrmann IE, Ellis PS, Greenfield A, Affara NA, Mitchell MJ. The mouse Y chromosome interval necessary for spermatogonial proliferation is gene dense with syntenic homology to the human AZFa region. Hum Mol Genet 1998; 7:1713-24. [PMID: 9736773 DOI: 10.1093/hmg/7.11.1713] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Delta Sxrb deletion interval of the mouse Y chromosome contains Spy, a spermatogenesis factor gene(s) whose expression is essential for the postnatal development of the mitotic germ cells, spermatogonia. The boundaries of Delta Sxrb are defined by the duplicated genes Zfy1 and Zfy2 and four further genes have previously been mapped within the interval: Ube1y and Smcy, linked with Zfy1 on a contig of 250 kb, and Dffry and Uty, which were unanchored. The interval was estimated to be >450 kb. In order to identify any further gene(s) that may underlie Spy, systematic exon trapping was performed on an extended contig, anchored on Zfy1, which covers 750 kb of the Delta Sxrb interval. Exons from two novel genes were isolated and placed together with Dffry and Uty on the contig in the order Dffry-Dby-Uty-Tspy-Eif2gammay-Smcy- Ube1y-Zfy1. All the genes, with the double exception of Tspy, are X-Y homologous and produce putatively functional, spliced transcripts. The tight linkage and order of Dffry, Dby and Uty was shown to be conserved in deletion intervals 5C/5D of the human Y chromosome by the construction of a contig of human PAC and YAC clones; this represents the first example of syntenic homology between Y chromosomes from two distinct mammalian orders. Interval 5C/5D contains the distal boundary of the AZFa interval, which, like Delta Sxrb, is believed to be necessary for spermatogonial development in the prepubertal testis. Our results therefore show that AZFa and Spy may be encoded by homologous genes.
Collapse
Affiliation(s)
- S Mazeyrat
- INSERM U491, Faculté de Médecine, 27 Boulevard Jean Moulin, 13385 Marseille cedex 5, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Laval SH, Dann JC, Butler RJ, Loftus J, Rue J, Leask SJ, Bass N, Comazzi M, Vita A, Nanko S, Shaw S, Peterson P, Shields G, Smith AB, Stewart J, DeLisi LE, Crow TJ. Evidence for linkage to psychosis and cerebral asymmetry (relative hand skill) on the X chromosome. AMERICAN JOURNAL OF MEDICAL GENETICS 1998; 81:420-7. [PMID: 9754628 DOI: 10.1002/(sici)1096-8628(19980907)81:5<420::aid-ajmg11>3.0.co;2-e] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The hypothesis that psychosis arises as a part of the genetic diversity associated with the evolution of language generates the prediction that illness will be linked to a gene determining cerebral asymmetry, which, from the evidence of sex chromosome aneuploidies, is present in homologous form on the X and Y chromosomes. We investigated evidence of linkage to markers on the X chromosome in 1) 178 families multiply affected with schizophrenia or schizoaffective disorder with a series of 16 markers spanning the centromere (study 1), and 2) 180 pairs of left-handed brothers with 14 markers spanning the whole chromosome (study 2). In study 1, excess allele-sharing was observed in brother-brother pairs (but not brother-sister or a small sample of sister-sister pairs) over a region of approximately 20 cM, with a maximum LOD score of 1.5 at DXS991. In study 2, an association between allele-sharing and degree of left-handedness was observed extending over approximately 60 cM, with a maximum lod score of 2.8 at DXS990 (approximately 20 cM from DXS991). Within the overlap of allele-sharing is located a block in Xq21 that transposed to the Y chromosome in recent hominid evolution and is now represented as two segments on Yp. In one of two XX males with psychosis we found that the breakpoint on the Y is located within the distal region of homology to the block in Xq21. These findings are consistent with the hypothesis that an X-Y homologous determinant of cerebral asymmetry carries the variation that contributes to the predisposition to psychotic illness.
Collapse
Affiliation(s)
- S H Laval
- Department of Psychiatry, Warneford Hospital, Oxford, UK
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Schwartz A, Chan DC, Brown LG, Alagappan R, Pettay D, Disteche C, McGillivray B, de la Chapelle A, Page DC. Reconstructing hominid Y evolution: X-homologous block, created by X-Y transposition, was disrupted by Yp inversion through LINE-LINE recombination. Hum Mol Genet 1998; 7:1-11. [PMID: 9384598 DOI: 10.1093/hmg/7.1.1] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The human X and Y chromosomes share many blocks of similar DNA sequence. We conducted mapping and nucleotide sequencing studies of extensive, multi-megabase homologies between Yp and Xq21, which do not recombine during male meiosis. We confirmed and built upon previous evidence that a Yp inversion had occurred during evolution: a single contiguous segment of Xq21 is homologous to two non-contiguous segments of Yp. We precisely defined and sequenced the inversion breakpoints, obtaining evidence that the inversion was mediated by recombination between LINE-1 elements in otherwise non-homologous regions. This inversion appears to have followed a single transposition of an approximately 4 Mb segment from the X to the Y chromosome. These events jointly account for the present arrangement of Yp-Xq21 homologous sequences. Based on Southern blotting studies of primates and of humans drawn from diverse populations, we conclude that both the X-Y transposition and the subsequent, LINE-mediated Yp inversion occurred after the divergence of hominid and chimp lineages but before the radiation of extant human populations. This evolutionary scenario is consistent with our finding of 99.3 +/- 0.2% nucleotide identity between the X and Y chromosomes within the transposed region, which suggests that the transposition occurred approximately 3-4 million years ago, near the time of emergence of Homo . Comparative sequencing of the entire human X and Y chromosomes may reveal a succession of transpositions, inversions and other rearrangements underlying the complex pattern of sequence similarities between the present-day sex chromosomes. With the possible exception of cubitus valgus, phenotypic features of Turner syndrome are absent in individuals monosomic for Yp-Xq21 homologous sequences, suggesting that most of the critical 'Turner genes' are found elsewhere on the X and Y chromosomes.
Collapse
Affiliation(s)
- A Schwartz
- Howard Hughes Medical Institute, Whitehead Institute and Department of Biology, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Abstract
The dichotomy between schizophrenia and manic-depressive illness is, as E. Kraepelin suspected, flawed; no unequivocal separation can be achieved. There are no categories of psychosis, but only continua of variation. However, the definition of nuclear symptoms by K. Schneider reveals the fundamental characteristics of the core syndrome--it is independent of the environment and constant in incidence across populations that have been separated for thousands of years. The associated genetic variation must be as old as Homo sapiens and represent a component of diversity that crosses the population as a whole. The fecundity disadvantage that accompanies the syndrome requires a balance in a substantial and universal advantage; this advantage, it is proposed, is the speciation characteristic of language; language and psychosis have a common evolutionary origin. Language, it is suggested, originated in a critical change on the sex chromosomes (the 'speciation event'--the genetic change that defined the species) occurring in East Africa between 100 and 250 thousand years ago that allowed the two hemispheres to develop with a degree of independence. Language can be understood as bi-hemispheric with one component function--a linear output sequence--confined to the dominant hemisphere--and a second--parallel distributed sampling occurring mainly in the non-dominant hemisphere. This mechanism provides an account of the generativity of language. The significance of nuclear symptoms is that these reflect a breakdown of bi-hemispheric coordination of language, perhaps specifically of the process of 'indexicalisation' (the distinction between 'I' and 'you') of self- versus other-generated references. Nuclear symptoms can be described as 'language at the end of its tether'; the phenomena and population characteristics of the nuclear syndrome of schizophrenia thus yield clues to the origin of the species.
Collapse
Affiliation(s)
- T J Crow
- Prince of Wales Centre, University Department of Psychiatry, Warneford Hospital, Oxford, UK
| |
Collapse
|
36
|
On the biology and politics of cognitive sex differences. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00042667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractThe male advantage in certain mathematical domains contributes to the difference in the numbers of males and females that enter math-intensive occupations, which in turn contributes to the sex difference in earnings. Understanding the nature and development of the sex difference in mathematical abilities is accordingly of social as well as scientific concern. A more complete understanding of the biological contributions to these differences can guide research on educational techniques that might someday produce more equal educational outcomes in mathematics and other academic domains.
Collapse
|
37
|
Brain differences, anthropological stories, and educational implications. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00042539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractGeary's anthropological assumptions are questioned as he uses literature influenced by sociobiology to back the claim that Female humans do not engage in environmental orientation. Yet, female gatherers or migrators do need and use spatial skills. Geary's exploration of gender differences in math skills is speculation that hasharmful, ungrounded, and misleading educational implications and applications, particularly in light of research on the status of gender equity in education.
Collapse
|
38
|
The twain shall meet: Uniting the analysis of sex differences and within-sex variation. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x0004259x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractSpatial and mathematical abilities may be “sex-limited” traits. A sex-limited trait has the same determinants of variation within the sexes, but the genetic or environmental effects would be differentially expressed in males and females. New advances in structural equation modeling allow means and variation to be estimated simultaneously. When these statistical methods are combined with a genetically informative research design, it should be possible to demonstrate that the genes influencing spatial and mathematical abilities are sex-limited in their expression. This approach would give an empirical confirmation of Geary's evolutionary speculations.
Collapse
|
39
|
Sex differences and evolutionary by-products. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00042643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractFrom the perspective of evolutionary theory, we believe it makes more sense to view the sex differences in spatial cognition as being an evolutionary by-product of selection for optimal rates of fetal development. Geary does not convince us that his proposed selective factors operated with “sufficient precision, economy, and efficiency.” Moreover, the archaeological evidence does not support his proposed evolutionary scenario.
Collapse
|
40
|
Between-sex differences are often averaging artifacts. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00042631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractThe central problem in Geary's theory is how differences are conceptualized. Recent research has shown that between-sex differences on certain tasks are a consequence of averaging within sex differences. A mixture distribution models between-sex differences on several tasks well and does not appear congenial to a sexual-selection perspective.
Collapse
|
41
|
Able youths and achievement tests. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00042618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractAchievement test differences between boys and girls and between young men and young women, mostly favoring males, extend far beyond mathematics. Such pervasive differences, illustrated here, may require an explanatory theory broader than Geary's.
Collapse
|
42
|
Differences in male and female cognitive abilities: Sexual selection or division of labor? Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00042503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractIn Darwinian terminology, “sexual selection” refers to purely reproductive competition and is conceptually distinct from natural selection as it affects reproduction generally. As natural selection may favor the evolution of sexual dimorphism by virtue of the division of labor between males and females, this possibility needs to be taken very seriously.
Collapse
|
43
|
Abstract
AbstractGeary's project faces the severe methodological difficulty of tracing the biological effects of gender on mathematical ability in a system that is massively open. Two methodological stratagems he uses are considered. The first is that pancultural sex differences are biological in nature, which is dubious in the domain of mathematics, since it is completely culture-bound. The second is that sociosexual differences are partly caused by biosexual differences, which renders his thesis unfalsifiable and empirically empty.
Collapse
|
44
|
Sex differences in mathematical abllity: Genes, environment, and evolution. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00042515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractGeary proposes a sociobiological hypothesis of how (and why) sex differences in math and spatial skills might have jointly arisen. His distinction between primary and secondary math skills is noteworthy, and in some ways analogous to the closed versus open systems postulated to exist for language. In this commentary issues concerning how genes might affect complex cognitive skills, the interpretation of heritability estimates, and prior research abilites are discussed.
Collapse
|
45
|
Abstract
AbstractWe challenge the notion that differences in spatial ability are the best or only explanation for observed sex differences in mathematical word problems. We suggest two ideas from the study of autism: sex differences in theory of mind and in central coherence.
Collapse
|
46
|
Is there a comparative psychology of implicit mathematical knowledge? Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00042448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractGeary suggests that implicit mathematical principles exist across human cultures and transcend sex differences. Is such knowledge present in animals as well, and is it sufficient to account for performance in all species, including our own? I attempt to trace the implications of Gearys target article for comparative psychology, questioning the exclusion of “subitizing” in describing human mathematical performance, and asking whether human researchers function as cultural agents with animals, elevating their implicit knowledge to secondary domains of numerical performance.
Collapse
|
47
|
On an evolutionary model of sex differences in mathematics: Do the data support the theory? Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00042473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractThe target article draws on evolutionary theory to formulate a biosocial model of sex differences in quantitative abilities. Unfortunately, the data do not support some of the crucial hypotheses. The male advantage in geometry is not appreciably greater than the male advantagi in algebra, and the greater male variability in mathematics cited by Gear is not cross-culturally invariant.
Collapse
|
48
|
We are far from understanding sex-related differences in spatial-mathematical abilities despite the theory of sexual selection. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x0004262x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
AbstractI have provided evidence that Geary's model does not explain male dominance in spatial abilities by sexual selection. The current literature concerning the relations of nonverbal IQ to testosterone, hand preference, and right- and left-hand skill, as well as the organizing effects of testosterone on cerebral lateralization during the perinatal period, does not support Geary's arguments.
Collapse
|
49
|
Do gender differences in spatial skills mediate gender differences in mathematics among high-ability students? Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00042412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractBased on Geary's theory, intelligence may determine which males utilize innate spatial knowledge to inform their mathematical solutions. This may explain why math gender differences occur mainly with higher abilities. In support, we found that mental rotation ability served as a mediator of gender differences on the math Scholastic Assessment Test for two high-ability samples. Our research suggests, however, that environment and biology interact to influence mental rotation abilities.
Collapse
|
50
|
Genetic influences on sex differences in outstanding mathematical reasoning ability. Behav Brain Sci 1996. [DOI: 10.1017/s0140525x00042655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractSexual selection provides an adequate partial explanation for the difference in means between the distributions, but fails to explain the difference in variance, that is, the overrepresentation of both boys with outstanding mathematical reasoning ability (OMRA) and boys with mental retardation. Other genetic factors are probably at work. While spatial ability is correlated with OMRA, so are other cognitive abilities. OMRA is not reducible to spatial ability; hence selection for navigational skill is unlikely to be the only mechanism by which males have gained an advantage in OMRA.
Collapse
|