Tuesday, October 18, 2011

Advanced paternal and grandpaternal age and schizophrenia

Schizophr Res. 2011 Oct 13. [Epub ahead of print]
Advanced paternal and grandpaternal age and schizophrenia: A three-generation perspective.
Frans EM, McGrath JJ, Sandin S, Lichtenstein P, Reichenberg A, Långström N, Hultman CM.
SourceDepartment of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.

BACKGROUND: Advanced paternal age has been linked with an increased risk of schizophrenia in the offspring. If age-related de novo mutations in the male germ line underlie this association, grandpaternal and paternal age would both be expected to influence the risk of schizophrenia. The aim of the current study was to explore the links between both paternal and grandpaternal age with respect to the risk of schizophrenia in a large, national register-based cohort.

METHOD: We linked the Swedish Multi-Generation and Hospital Discharge Registers and compared parents' ages at offspring birth for 20,582 schizophrenia-affected and 100,176 non-affected individuals. Grandparents' ages at the birth of the parent were compared between 2511 affected and 15,619 non-affected individuals. The risk of schizophrenia was examined with logistic regression when the predictor variable (parent or grandparent age) varied across age strata.

RESULTS: After adjusting for maternal age, birth year and proband sex, we confirmed that offspring of older fathers had an increased risk of schizophrenia. Compared to those with paternal age 20-24years, those with fathers >55years had a two-fold increased risk of schizophrenia. With respect to grandparent age, older maternal (but not paternal) grandfather age was associated with an increased risk of schizophrenia. Compared to maternal grandfather age 20-24years, those with maternal grandfathers >55years had a significantly increased risk of schizophrenia (adjusted odds ratio and 95% confidence intervals; 2.79, 1.71-4.56). The pattern of results was essentially unchanged when we examined male and female probands separately.

CONCLUSION: This is the first study to report an association between grandpaternal age and risk of schizophrenia. The selective effect of advanced maternal grandfather age suggests that the biological mechanisms involving the X-chromosome may differentially contribute to the association between paternal age and offspring risk of schizophrenia.

Copyright © 2011. Published by Elsevier B.V.


Wednesday, October 05, 2011

De novo copy number variants associated with intellectual disability have a paternal origin and age bias.

Med Genet. 2011 Oct 3. [Epub ahead of print]
De novo copy number variants associated with intellectual disability have a paternal origin and age bias.
Hehir-Kwa JY, Rodríguez-Santiago B, Vissers LE, de Leeuw N, Pfundt R, Buitelaar JK, Pérez-Jurado LA, Veltman JA.
Source1Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences and Institute for Genetic and Metabolic Disorders, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.

BackgroundDe novo mutations and structural rearrangements are a common cause of intellectual disability (ID) and other disorders with reduced or null reproductive fitness. Insight into the genomic and environmental factors predisposing to the generation of these de novo events is therefore of significant clinical importance.MethodsThis study used information from single nucleotide polymorphism microarrays to determine the parent-of-origin of 118 rare de novo copy number variations (CNVs) detected in a cohort of 3443 patients with ID.ResultsThe large majority of these CNVs (76%, p=1.14×10(-8)) originated on the paternal allele. This paternal bias was independent of CNV length and CNV type. Interestingly, the paternal bias was less pronounced for CNVs flanked by segmental duplications (64%), suggesting that molecular mechanisms involved in the formation of rare de novo CNVs may be dependent on the parent-of-origin. In addition, a significantly increased paternal age was only observed for those CNVs which were not flanked by segmental duplications (p=0.02).ConclusionThis indicates that rare de novo CNVs are increasingly being generated with advanced paternal age by replication based mechanisms during spermatogenesis.

PMID:21969336[PubMed - as supplied by publisher]