The lack of association between catechol-O-methyltransferase (COMT) Val108/158Met and brain-derived neurotrophic factor (BDNF) Val66Met polymorphisms and schizophrenia in a group of Turkish population

• Published in: Neurology, psychiatry, and brain research psychiatry, and brain research, 2013-08, Vol.19 (3), p.102-108
• Main Authors: Kayahan, Bülent, Kaymaz, Burçin Tezcanlı, Altıntoprak, Ayşe Ender, Aktan, Çağdaş, Veznedaroğlu, Baybars, Kosova, Buket
• Format: Article
• Language: English
• Subjects: BDNF Val66Met; COMT Val108/158Met; Polymorphism; Schizophrenia
• ISSN: 0941-9500
• DOI: 10.1016/j.npbr.2013.05.004

Schizophrenia is a complex neuropsychiatric disorder with deficits of multiple domains of cognitive functions, volition and emotions. Family and twin studies have provided cumulative evidence for the genetic basis of schizophrenia. The aetiolgy of this disease involves the interplay of multifactiorial inheritance operating on brain maturational processes and polygenic inheritance with some genes showing susceptibility at many genomic locations such as 22q and 11q. The catechol-O-methyltransferase (COMT-22q11) is an extensively studied candidate gene for schizophrenia. COMT acts as an enzymatic detoxicating barrier between the blood and other tissues regulating the amounts of active dopamine and norepinephrine in various parts of the brain and therefore to be associated with schizophrenia. The presence of a common functional single nucleotide polymorphism (SNP) in exon 4 [Guanine (G) Adenine (A); Val108/158Met], alters the enzymatic activity with a trimodal distribution of high-HH, intermediate-HL and low-LL activity alleles which appear to have association with schizophrenia. Brain-derived neurotrophic factor (BDNF-11q13) is a member of the nerve growth factor family working as a molecular regulator of neuronal development and plasticity. Molecules that are critical in the development and survival of neurons such as BDNF play a significant role in the neuropathology of schizophrenia. While upregulation of BDNF increases the neuronal cell size and synaptic plasticity, a functional polymorphism at codon 66 [G→A; Val66Met] down regulates this process and induces schizophrenia. In the present study, our aim was to investigate the differences in allele frequencies between schizophrenic patients [n=97 (51 men, 46 women)] and control group [n=376 (228 men, 148 women)] subjects. When the control and schizophrenia groups were compared for BDNFVal66Met polymorphism, we did not find a significant difference between the study groups either for genotype (χ2=3.370447, p>0.05) or Val/Met haplotype analysis (χ2=2.840264, p>0.05). When a comparison was revealed for COMT-Val108/158Met polymorphism, no significant difference was detected among schizophrenia and control groups for genotype (χ2=0.373330, p>0.05) and Val/Met haplotype analysis (χ2=0.339073, p>0.05). When the control and study groups were compared for BDNFVal66Met–COMTVal108/158Met polymorphisms compound genotype and haplotype analyses, there was no significant difference between the two groups (χ2=11.015; p>0.0