Wednesday, January 11, 2012

James Crow Dies

James Crow Dies

January 11, 2012

James Crow, who was a population geneticist at the University of Wisconsin-Madison, has died, reports The New York Times. He was 95. Crow studied mutational load, and was part of on a National Academy of Sciences committee that assessed mutational damage to the populations of Hiroshima and Nagasaki following the use of atomic bombs there. He also was on a committee that paved the way for using DNA forensics in court. The Times notes that when Crow began teaching in the 1940s and 1950s, the field of genetics underwent rapid changes. "When anxious students asked Dr. Crow what would be in the exams, he would tell them that the questions were the same every year but that the answers were different," the Times says.

Saturday, January 07, 2012

Neuron. 2011 Dec 22;72(6):951-63. High Frequencies of De Novo CNVs in Bipolar Disorder and Schizophrenia.

Neuron. 2011 Dec 22;72(6):951-63.

High Frequencies of De Novo CNVs in Bipolar Disorder and Schizophrenia.

Malhotra D, McCarthy S, Michaelson JJ, Vacic V, Burdick KE, Yoon S, Cichon S, Corvin A, Gary S, Gershon ES, Gill M, Karayiorgou M, Kelsoe JR, Krastoshevsky O, Krause V, Leibenluft E, Levy DL, Makarov V, Bhandari A, Malhotra AK, McMahon FJ, Nöthen MM, Potash JB, Rietschel M, Schulze TG, Sebat J.


Beyster Center for Genomics of Psychiatric Diseases, University of California, San Diego, La Jolla, CA 92093, USA; Department of Psychiatry, University of California, San Diego, La Jolla, CA 92093, USA; Stanley Institute for Cognitive Genomics, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 12824, USA.


While it is known that rare copy-number variants (CNVs) contribute to risk for some neuropsychiatric disorders, the role of CNVs in bipolar disorder is unclear. Here, we reasoned that a contribution of CNVs to mood disorders might be most evident for de novo mutations. We performed a genome-wide analysis of de novo CNVs in a cohort of 788 trios. Diagnoses of offspring included bipolar disorder (n = 185), schizophrenia (n = 177), and healthy controls (n = 426). Frequencies of de novo CNVs were significantly higher in bipolar disorder as compared with controls (OR = 4.8 [1.4,16.0], p = 0.009). De novo CNVs were particularly enriched among cases with an age at onset younger than 18 (OR = 6.3 [1.7,22.6], p = 0.006). We also confirmed a significant enrichment of de novo CNVs in schizophrenia (OR = 5.0 [1.5,16.8], p = 0.007). Our results suggest that rare spontaneous mutations are an important contributor to risk for bipolar disorder and other major neuropsychiatric diseases.

Copyright © 2011 Elsevier Inc. All rights reserved.

Wednesday, January 04, 2012

The results of these different studies are confirmed by two recent meta-analyses which found an increased risk of schizophrenia in offspring of fathers older than 35 years

Encephale. 2011 Jun;37(3):199-206. Epub 2011 Apr 2.

[Influence of paternal age in schizophrenia].

[Article in French]

Hubert A, Szöke A, Leboyer M, Schürhoff F.


Pôle de psychiatrie du CHU de Créteil, groupe hospitalier Henri-Mondor-Albert-Chenevier, AP-HP, 40, rue Mesly, 94000 Créteil, France.



Schizophrenia is an aetiologically heterogeneous syndrome, with a strong genetic component. Despite a reduced fertility in this disorder, its prevalence is maintained and could be explained by de novo genetic mutations. Advanced paternal age (APA) is a major source of new mutations in human beings and could thus be associated with an increased risk of developing schizophrenia in offspring. New mutations related to APA have been implicated as a cause of sporadic cases in several autosomal dominant diseases and also in neurodevelopmental diseases, autism, intellectual disabilities, and social functioning. The aim of the present study was to summarize the results of studies investigating the role of APA, and to discuss some interpretations.


All relevant studies were identified through the National Library of Medicine (PubMed(®) database). Keywords used for research were "age" and "schizophrenia" linked to "paternal or father". We have identified and analysed eight cohort studies, five case-control studies, two meta-analyses, and one review concerning different father's mutations potentially transmitted, two studies comparing paternal age at conception between sporadic versus familial cases of schizophrenia. All studies selected have been published between 2000 and 2009.


After controlling for several confounding factors including maternal age, the relative risk of schizophrenia increased from 1.84 to 4.62 in offspring of fathers with an older age of fatherhood. Mother's age showed no significant effects after adjusting for paternal age. There was a significant association between paternal age and risk of developing schizophrenia, there was a weaker association with psychosis.


The results of these different studies are confirmed by two recent meta-analyses which found an increased risk of schizophrenia in offspring of fathers older than 35 years. Two main hypotheses could explain these results. The first one is based on the presence of new mutations in the spermatogonia, possibly because of accumulating replication errors in spermatogonial cell lines. This hypothesis is confirmed by Malaspina et al. (2002) [19], who found that patients without a family history of schizophrenia had significantly older fathers than probands with a positive family history of schizophrenia. However, this result has not been confirmed by other studies, and paternal age effect could be also explained by a mechanism called imprinting, which is a form of gene regulation. The second hypothesis is based on the fact that fathers with schizophrenia spectrum personality disorder, known to be genetically related to schizophrenia, could have an advanced age at conception. However, regarding this hypothesis, advanced maternal age at conception should be a risk factor for schizophrenia, and this is not the case. Thus, the first hypothesis seems more plausible than the second. APA has been identified as a risk factor for other psychiatric disorders such as autism, bipolar disorder, obsessive-compulsive disorder, and phobia, and thus seems to be a non-specific risk factor. Furthermore, its association with impaired neurocognitive outcomes during infancy and childhood in normal populations raises the question of the phenotype linked to APA.


APA at conception appears to be a risk factor for schizophrenia. This risk factor probably interacts with genetic factors in a gene-environment interaction. To date, there is no validated cut-off at which the risk is significantly increased in offspring. In the future, studies could benefit from analyzing the phenotype related to APA.

Copyright © 2010 L'Encéphale, Paris. Published by Elsevier Masson SAS. All rights reserved.

PMID: 21703435 [PubMed - indexed for MEDLINE]

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