Chromosomes, Human, X

Publication Title: 
American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics: The Official Publication of the International Society of Psychiatric Genetics

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.

Author(s): 
Giouzeli, Maria
Williams, Nic A.
Lonie, Lorne J.
DeLisi, Lynn E.
Crow, Timothy J.
Publication Title: 
Journal of the American Academy of Child and Adolescent Psychiatry

OBJECTIVE: To comment on the article in this issue of the Journal by Professor Michael Rutter, "Environmentally Mediated Risks for Psychopathology: Research Strategies and Findings," in the context of current research findings on gene-environment interaction, epigenetics, and gene expression. METHOD: Animal and human studies are reviewed that differentiate the role of gene expression in developmental biology and psychopathology as well as studies that begin to specify the biological mechanisms involved in determining how genotype is translated into phenotype.

Author(s): 
Kramer, Douglas A.
Publication Title: 
Human Genetics

This is the first report of a full genome scan of sexual orientation in men. A sample of 456 individuals from 146 families with two or more gay brothers was genotyped with 403 microsatellite markers at 10-cM intervals. Given that previously reported evidence of maternal loading of transmission of sexual orientation could indicate epigenetic factors acting on autosomal genes, maximum likelihood estimations (mlod) scores were calculated separated for maternal, paternal, and combined transmission.

Author(s): 
Mustanski, Brian S.
Dupree, Michael G.
Nievergelt, Caroline M.
Bocklandt, Sven
Schork, Nicholas J.
Hamer, Dean H.
Publication Title: 
Schizophrenia Bulletin

The causal mechanism underlying the well-established relation between advancing paternal age and schizophrenia is hypothesized to involve mutational errors during spermatogenesis that occur with increasing frequency as males age. Point mutations are well known to increase with advancing paternal age while other errors such as altered copy number in repeat DNA and chromosome breakage have in some cases also been associated with advancing paternal age. Dysregulation of epigenetic processes may also be an important mechanism underlying the association between paternal age and schizophrenia.

Author(s): 
Perrin, Mary C.
Brown, Alan S.
Malaspina, Dolores
Publication Title: 
American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics: The Official Publication of the International Society of Psychiatric Genetics

Monozygotic (MZ) twins may be subject to epigenetic modifications that could result in different patterns of gene expression. Several lines of evidence suggest that epigenetic factors may underlie mental disorders such as bipolar disorder (BD) and schizophrenia (SZ). One important epigenetic modification, of relevance to female MZ twins, is X-chromosome inactivation. Some MZ female twin pairs are discordant for monogenic X linked disorders because of differential X inactivation.

Author(s): 
Rosa, Araceli
Picchioni, Marco M.
Kalidindi, Sridevi
Loat, Caroline S.
Knight, Joanne
Toulopoulou, Timothea
Vonk, Ronald
van der Schot, Astrid C.
Nolen, Willem
Kahn, RenÈ S.
McGuffin, Peter
Murray, Robin M.
Craig, Ian W.
Publication Title: 
Schizophrenia Research

OBJECTIVE: To achieve a unified concept of the aetiology of psychosis. BACKGROUND: The nuclear symptoms of "schizophrenia" occur with approximately the same age- and sex-specific incidence in all human populations. No substantive environmental precipitant has been identified, and yet these "illnesses" are associated with deviations in brain structure that are uniform across populations, are established late in development and relate to the capacity for language. No genes have been identified by linkage or association strategies.

Author(s): 
Crow, Timothy J.
Publication Title: 
Laterality

A theory of the genetic basis of cerebral asymmetry is outlined according to which (1) a single right-shift factor in all human individuals interacts with (2) epigenetic variation that is apparently random, transmissible between parent and child, but with a half-life extending over a small number of generations. The right-shift factor arose late (150 to 200 thousand years ago [KYA]) in hominid evolution as a mutation in the X copy of a gene pair (Protocadherin 11XY) in a region of homology between the X and Y chromosomes created by a duplication 6MYA at the chimpanzee hominid separation.

Author(s): 
Crow, T. J.
Publication Title: 
Molecular Psychiatry

Less than 2% of the 80-90% heritability of major psychiatric disease, for example, schizophrenia and manic-depressive illness is attributable to genes identified by linkage and association. Where is the missing heritability? The recently described PRDM9 gene imposes epigenetic stability on the XY body in male meiosis including Sapiens-specific variation relating to a gene pair (Protocadherin11XY) created by X to Y duplication at 6MYA.

Author(s): 
Crow, T. J.
Publication Title: 
Clinical Genetics

The psychoses (schizophrenia and bipolar disorder) occur in all populations with approximately uniform incidence and sex-dependent age of onset. Core symptoms involve aspects of language; brain structural deviations are sex and hemisphere-related. Genetic predisposition is unaccounted for by linkage or association. The hypothesis is proposed that the 'missing heritability' is epigenetic in form and generated in meiosis on a species-specific XY chromosomal template. A duplication from Xq21.3 to Yp11.2 that occurred 6 million years ago is proposed as critical to hominin evolution.

Author(s): 
Crow, T. J.
Publication Title: 
BMC genomics

BACKGROUND: As the most stable and experimentally accessible epigenetic mark, DNA methylation is of great interest to the research community. The landscape of DNA methylation across tissues, through development and in disease pathogenesis is not yet well characterized. Thus there is a need for rapid and cost effective methods for assessing genome-wide levels of DNA methylation.

Author(s): 
Pidsley, Ruth
Y Wong, Chloe C.
Volta, Manuela
Lunnon, Katie
Mill, Jonathan
Schalkwyk, Leonard C.

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