Season of birth interacts with measures of inbreeding in multiplex schizophrenia pedigrees: evidence from genetic isolates in Daghestan
While the season-of-birth effect is one of the most consistent epidemiological features of schizophrenia, there is a lack of consistency with respect to the interaction between season of birth and family history of schizophrenia. Apart from family history, measures related to consanguinity can be used as proxy markers of genomic heterogeneity. Thus, these measures may provide an alternate, indirect index of genetic susceptibility. We had the opportunity to explore the interaction between season of birth and measure of consanguinity in well-described genetic isolates in Daghestan, some of which are known for their relatively high prevalence of schizophrenia. Our previous population-genetic study showed Daghestan has an extremely high genetic diversity between the ethnic populations and a low genetic diversity within them. The isolates selected for this study include some with more than 200 and some with less than 100 generations of demographical history since their founding. Based on pedigrees of multiply-affected families, we found that among individuals with schizophrenia, the measure of consanguinity was significantly higher in the parents of those born in winter/spring compared to those born in summer/autumn. Furthermore, compared to summer/autumn born, winter/spring born individuals with schizophrenia had an earlier age-of-onset, and more prominent auditory hallucinations. Our results suggest that the offspring of consanguineous marriages, and thus those with reduced allelic heterogeneity, may be more susceptible to the environmental factor(s) underpinning the season-of-the effect in schizophrenia.
- N.I. Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, 119991, Russia, firstname.lastname@example.org
- Queensland Centre for Mental Health Research, Department of Psychiatry, University of Queensland, The Park Centre for Mental Health, Wacol, QLD 4076, Australia
-  E.F. Torrey, J. Miller, R. Rawlings and R.H. Yolken: “Seasonality of births in schizophrenia and bipolar disorder: a review of the literature”, Schizophr. Res., Vol. 28, (1997), pp. 1–38. http://dx.doi.org/10.1016/S0920-9964(97)00092-3[Crossref]
-  G. Davies, J. Welham, D. Chant, E.F. Torrey and J. McGrath: “Season of birth effect and latitude: a systematic review and meta-analysis of Northern Hemisphere studies”, Schizophr. Bull., Vol. 29(3), (2003), pp. 587–593.
-  J.J. McGrath and J.L. Welham: “Season of birth and schizophrenia: a systematic review and meta-analysis of data from the Southern Hemisphere”, Schizophr. Res., Vol. 35, (1999), Vol. 237-242.
-  A.S. Brown and E.S. Susser: In utero infection and adult schizophrenia. Ment. Retard. Dev. Disabil. Res. Rev., Vol. 8(1), (2002), pp. 51–57. http://dx.doi.org/10.1002/mrdd.10004[Crossref]
-  J. McGrath: “Hypothesis: is low prenatal vitamin D a risk-modifying factor for schizophrenia?”, Schizophr. Res. , Vol. 40(3), (1999), pp. 173–177. http://dx.doi.org/10.1016/S0920-9964(99)00052-3[Crossref]
-  E. Shur: “Season of birth in high and low genetic risk schizophrenics”, Br. J. Psychiatry, Vol. 140, (1982), pp. 410–415. http://dx.doi.org/10.1192/bjp.140.4.410[Crossref]
-  P.B. Mortensen, C.B. Pedersen, T. Westergaard, J. Wohlfahrt, H. Ewald, O. Mors, P.K. Andersen and M. Melbye: “Effects of family history and place and season of birth on the risk of schizophrenia”, N. Engl. J. Med., Vol. 340, (1999), pp. 603–608. http://dx.doi.org/10.1056/NEJM199902253400803[Crossref]
-  J.M. Suvisaari, J.K. Haukka and J.K. Lonnqvist: “No association between season of birth of patients with schizophrenia and risk of schizophrenia among their siblings”, Schizophr. Res., Vol. 66(1), (2004), pp. 1–6. http://dx.doi.org/10.1016/S0920-9964(02)00506-6[Crossref]
-  J.M. Hettema, D. Walsh and K.S. Kendler: “Testing the effect of season of birth on familial risk for schizophrenia and related disorders”, Br. J. Psychiatry, Vol. 168(2), (1996), pp. 205–209. http://dx.doi.org/10.1192/bjp.168.2.205[Crossref]
-  A.E. Pulver, K.Y. Liang, P.S. Wolyniec, J. McGrath, B.A. Melton, L. Adler and B. Childs: “Season of birth of siblings of schizophrenic patients”, Br. J. Psychiatry, Vol. 160, (1992), pp. 71–75.
-  E. O’Callaghan, K. Colgan, D. Cotter, C. Larkin, D. Walsh and J.L. Waddington: “Evidence for confinement of winter birth excess in schizophrenia to those born in cities”, Schizophr. Res., Vol. 6, (1992), p. 102. http://dx.doi.org/10.1016/0920-9964(92)90113-J[Crossref]
-  J. Chotai, A. Serretti, E. Lattuada, C. Lorenzi and R. Lilli: “Gene-environment interaction in psychiatric disorders as indicated by season of birth variations in tryptophan hydroxylase (TPH), serotonin transporter (5-HTTLPR) and dopamine receptor (DRD4) gene polymorphisms”, Psychiatry Res., Vol. 119(1-2), (2003), pp. 99–111. http://dx.doi.org/10.1016/S0165-1781(03)00112-4[Crossref]
-  G. Seeger, P. Schloss, M.H. Schmidt, A. Ruter-Jungfleisch and F.A. Henn: “Gene environment interaction in hyperkinetic conduct disorder (HD + CD) as indicated by season of birth variations in dopamine receptor (DRD4) gene polymorphism”, Neurosci. Lett., Vol. 366(3), (2004), pp. 282–286. http://dx.doi.org/10.1016/j.neulet.2004.05.049[Crossref]
-  T.A. Markow: “Genetics and developmental stability: an integrative conjecture on aetiology and neurobiology of schizophrenia”, Psychol. Med., Vol. 22, (1992), pp. 295–305. http://dx.doi.org/10.1017/S0033291700030233[Crossref]
-  K.B. Bulayeva, S.M. Leal, T.A. Pavlova, R.M. Kurbanov, S.J. Glatt, O.A. Bulayev and M.T. Tsuang: “Mapping genes of complex psychiatric diseases in Daghestan genetic isolates”, Am. J. Med. Genet., B. Neuropsychiatr. Genet., Vol. 132(1), (2005), pp. 76–84.
-  K. Bulayeva et al.: “Genome-Wide Linkage Scan of Schizophrenia: a Cross-Isolates Study”, Genomics, (2006), in press.
-  M. Gadjiev, O. Davudov and S. Shihsaidov: History of Daghestan, Moscow, Nauka, 1996.
-  K. Bulayeva: Genetic basis of human psychophysiology, Moscow, Nauka, 1991.
-  K. Bulayeva, L.B. Jorde, C. Ostler, S. Watkins, O. Bulayev and H. Harpending: “Genetics and population history of Caucasus populations”, Hum. Biol., Vol. 75(6), (2003), pp. 837–853.
-  K. Bulayeva, L. Jorde, S. Watkins, C. Ostler, T.A. Pavlova, O.A. Bulayev, S. Tofanelli, G. Paoli and H. Harpending: “Ethnogenomic diversity of Caucasus, Daghestan”, Am. J. Hum. Biol., Vol. 18(5), (2006), pp. 610–620. http://dx.doi.org/10.1002/ajhb.20531[Crossref]
-  J.I. Nurnberger, M.C. Blehar, C.A. Kaufmann, C. York-Cooler, S.G. Simpson, J. Harkavy-Friedman, J.B. Severe, D. Malaspina and T. Reich: “Diagnostic interview for genetic studies: rationale, unique features and training”, Arch. Gen. Psychiatry, Vol. 51, (1994), pp. 849–862.
-  K. Bulayeva: “Overview of genetic-epidemiological studies in ethnically and demographically diverse isolates of Dagestan, Northern Caucasus, Russia”, Croat. Med. J., Vol. 47(4), (2006), pp. 641–649.
-  R.A. Yeo, S.W. Gangestad, C. Edgar and R. Thoma: “The evolutionary genetic un derpinnings of schizophrenia: the developmental instability model”, Schizophr.Res., Vol. 39(3), (1999), pp. 197–206. http://dx.doi.org/10.1016/S0920-9964(99)00074-2[Crossref]
-  C.H. Waddington: “Canalization of development and genetic assimilation of acquired characters”, Nature, Vol. 183(4676), (1959), pp. 1654–1655. http://dx.doi.org/10.1038/1831654a0[Crossref]