Neurocase, 2015 Vol. 21, No. 1, 106–108, http://dx.doi.org/10.1080/13554794.2013.873061

Family-based association study between monoamine oxidase A (MAOA) gene promoter VNTR polymorphism and Tourette’s syndrome in Chinese Han population Shiguo Liua,b,c, Xueqin Wangd, Longqiang Xue, Lanlan Zhengd, Yinlin Ged* and Xu Maf,g,h a

Shandong Provincial Key Laboratory of Metabolic Disease, The Affiliated Hospital of Medical College, Qingdao University, Qingdao 266003, China; bInstitute of Clinical Research, The Affiliated Hospital of Medical College, Qingdao University, Qingdao 266003, China; c Genetic Laboratory, The Affiliated Hospital of Medical College, Qingdao University, Qingdao 266003, China; dMedical School, Qingdao University, Qingdao, China; eDepartment of Psychiatry, Medical College, Qingdao University, Qingdao 266021, China; f Graduate school, Peking Union Medical College, Beijing, China; gNational Research Institute for Family Planning, Beijing 100081, China; hWorld Health Organization Collaborating Centre for Research in Human Reproduction, Beijing, China (Received 20 April 2013; accepted 26 September 2013) To clarify the association of monoamine oxidase A– variable number of tandem repeat (MAOA-pVNTR) with susceptibility to Tourette’s syndrome (TS) in Chinese Han population we discuss the genetic contribution of MAOA–VNTR in 141 TS patients including all their parents in Chinese Han population using transmission disequilibrium test (TDT) design. Our results revealed that no significant association was found in the MAOA gene promoter VNTR polymorphism and TS in Chinese Han population (TDT = 1.515, df = 1, p > 0.05). The negative result may be mainly due to the small sample size, but we don’t deny the role of gene coding serotonergic or monoaminergic structures in the etiology of TS. Keywords: TS; MAOA; TDT; VNTR

Introduction Tourette’s syndrome (TS) is a hereditary neuropsychiatric disorder with complex inheritance and phenotypic manifestations characterized by multiple motor and phonic tics that wax and wane over time, affecting up to 1% of children as well as many adults all over the world (Robertson, Eapen, & Cavanna, 2009). Twins and families studies (Pauls, Cohen, Heimbuch, Detlor, & Kidd, 1981; Price, Kidd, Cohen, Pauls, & Leckman, 1985) provided strong evidence that genetic factors, particularly polygenic hereditary patterns, are involved in the vertical transmission of TS. Apart from genetic factors, various environmental and lifestyle factors also contribute to the TS etiology. It is publicly identified that dopamine defects are associated with the development of TS, dopamine-related candidate genes, including tyrosine hydroxylase, catechol-O-methyl transferase gene COMT (Tarnok et al., 2007), dopamine D4 receptor (DRD4) (Grice et al., 1996), dopamine transporter (DAT1) (Yoon et al., 2007), dopamine β hydroxylase, and tyrosine oxygenase, become the focus in the TS etiology. As one of the X-linked dopamine-related candidate genes, Gade et al. (1998) reported that the monoamine oxidase A (MAOA) gene has association with phenotypic effect in TS. However, its exact pathogenesis is still unclear. MAOA, located at chromosome Xp21-p11 (Ozelius et al., 1988), is involved in the serotonergic pathway. It is widely expressed in the catecholaminergic neuron and plays a

vital role in the catabolism of monoaminergic neurotransmitters including serotonin, norepinephrine, and dopamine. Due to its ability of influencing monoaminergic activity, the MAOA has been a focus in the investigation of aggression in animals and violent behavior in humans and therefore has been commonly a candidate gene in the study of psychiatric diseases and behavioral traits. Transcriptional level of MAOA is thought to be moderated by a 30bp variable nucleotide repeat, which is localized 1.2 kb upstream of the coding sequences in its promoter region. This variable number of tandem repeat (VNTR) includes 2, 3, 3.5, 4, and 5 copies of the repeat sequence; 3 and 4 copies are more common than other repeats in human populations (Sabol, Hu, & Hamer, 1998). Also, the transcriptional activity of 3.5 and 4 repeat alleles is 2–10 times higher compared to other repetitions. The MAOA promoter VNTR has been also identified as a genetic factor that can regulate antisocial behavior (Sjoberg et al., 2008), depression (Lung, Tzeng, Huang, & Lee, 2011), OCD, and alcoholism (Gokturk et al., 2008). Since dopamine (one substrate of MAOA) defects are associated with TS, described as previously, furthermore, the transcriptional activity of MAOA is regulated by its promoter VNTR polymorphism, and then we carry this research to explore this hypothesis: is there any relevance between the MAOA promoter VNTR polymorphism and TS development by a family-based genotype-risk association study in Chinese Han population?

*Corresponding author. Email: [email protected] Present affiliation for Yinlin Ge is Department of Biochemistry and Molecular Biology, Qingdao University Medical College, Qingdao, China. © 2014 Taylor & Francis

Neurocase Materials and methods The subjects for this study were recruited from the Affiliated Hospital of Medical College of Qingdao University and Linyi People’s Hospital. TS cases were composed of 25 female and 116 male outpatients, aged between 5 and 18 years (10.3 ± 4.5). There are 141 trios including patients and their parents. All probands were diagnosed independently by two experienced psychiatrists according to the DMS-IV criteria and the TS Classification Study Group. The study protocol was approved by the Human Ethics Committee of the Medical School Hospital of Qingdao University and the National Research Institute for Family Planning. Informed written consent was obtained from every participant or their legal guardians after a complete and extensive description. DNA was extracted from the peripheral blood using standard methods. Polymerase chain reaction (PCR) of MAOA-pVNTR was performed by the following primer reported previously: former: 5′ ACAGCCTGACCGTGGAGAAG-3′, reverse: 5′-GAAC GGACGCTCCATTCGGA-3′. The PCR products were separated by electrophoresis on 4% agarose gels and visualized and genotyping was carried out by ethidium– bromide staining. Several subjects were selected to confirm genotype by DNA sequencing techniques. We conducted a family-based genotype-risk association study by transmission disequilibrium test (TDT) design (X2 = (b – c) 2/(b + c), where “b” stands for transmissions of the high-risk allele and “c” stands for transmissions of the low-risk allele from heterozygous (b/c) parents).

Results In case of the MAOA gene promoter VNTR polymorphism, genotyping revealed six different alleles distinguished by the number of their 30 bp repeat sequence: 1-, 2-, 3-, 3.5-, 4-, and 5- repeat alleles. We compared the highactivity alleles (3.5R and 4R) and low-activity alleles (all but 3.5 and 4R) reported by Sabol et al. (Lung et al., 2011). TDT analysis showed no significant association between MAOA gene promoter VNTR polymorphism and TS in Chinese Han population (X2 = 1.515, df = 1, p > 0.05) (Table 1).

Discussion The functional VNTR polymorphism has been shown to affect the transcriptional activity of the MAOA gene promoter, suggesting that it may indeed influence brain 5-HT, norepinephrine and dopamine levels. Therefore, the VNTR polymorphism of MAOA gene promoter is linked to a range of diseases, from obsessive–compulsive disorder and TS to major depressive disorder and other behavior or

Table 1.

107 TDT analysis for MAO-A. Non-transmitted alleles

Transmitted alleles

H

L

Total

H L Total

17 38 55

28 58 86

45 96

Note: X2 = 1.515, p > 0.05, “H” is short for “high-activity” alleles (3.5R and 4R) and “L” is short for “low-activity” alleles (all but 3.5R and 4R).

physiologic-related disorders. Kazuhiko et al. (2009) investigated the association between MAOA–VNTR polymorphism and methamphetamine psychosis, and found significant difference between males with persistent versus transient methamphetamine psychosis. However, Gokturk et al. (2008) tested the linkage of polymorphism of MAOA– VNTR to severe alcoholism in a case-control manner and did not find any significant evidence in the association of MAOA–VNTR to alcoholism. In the present study we evaluated the genetic contribution of the MAOA–pVNTR polymorphism in 141 TS patients including all their parents in Chinese Han population using TDT design, and no significant differences were found in MAOA–VNTR allele frequencies. Although a significant association between the X-linked MAOA gene and TS phenotype has been identified by Gade et al. (Sabol et al., 1998) in 1998 and MAOA–VNTR association with susceptibility to TS in French Canadian population by family-based study by Díaz-Anzaldúa et al. (2004), large genetic association and linkage studies to date have failed to implicate MAOA gene as the cause of TS. Moreover, genetic variants with minor effects in association studies between complex inheritance disorders (including ADHD, TS, and OCD) and dopamine candidate genes often lead to contradictory results among different methods, populations and experimental designs (Zsofia, Anna, & Maria, 2011). Association study between MAOA gene promoter VNTR polymorphism and TS in Chinese Han population has not been reported previously. In summary, our result suggested that there may be a lack of association between the TS and MAOA-pVNTR in Chinese Han population, which is different from the previous study in French Canadian population. This may be due to different populations. However, the present study has several limitations. First, the power of the present study was limited by its small sample size. Second, TDT test for X-linked genes linkage analyses is not so ripe. Last but not the least, the lack of significance for MAOA–VNTR polymorphisms in conferring liability to TS does not exclude a role of different functional polymorphisms in genes coding for serotonergic or monoaminergic structure in the etiology of TS. Thus, further investigation should be performed in a large

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sample of Chinese Han population and also different populations to evaluate our findings. Acknowledgments We thank all the probands for the participation. Shiguo Liu and Xueqin Wang contribute equally to this work.

Funding This work was supported by the National Natural Science Foundation of China [grant number 81371499], [grant number 30971586]; the National Infrastructure Program of Chinese Genetic Resources [grant number 2006DKA21300].

References Díaz-Anzaldúa, A., Jobber, R., Riviere, J. B., Dion, Y., Lespérance, P., Richer, F., ... Rouleau, G. A. (2004). Tourette syndrome and dopaminergic genes: A familybased association study in the French Canadian founder population. Molecular Psychiatry, 9(3), 272–277. Gade, R., Muhleman, D., Blake, H., MacMurray, J., Johnson, P., Verde, R., … Comings, D. E. (1998). Correlation of length of VNTR alleles at the X-linked MAOA gene and phenotypic effect in Tourette syndrome and drug abuse. Molecular Psychiatry, 3(1), 50–60. Gokturk, C., Schultze, S., Nilsson, K. W., von Knorring, L., Oreland, L., & Hallman, J. (2008). Serotonin transporter (5-HTTLPR) and monoamine oxidase (MAOA) promoter polymorphisms in women with severe alcoholism. Archives of Women’s Mental Health, 11(5–6), 347–355. Grice, D. E., Leckman, J. F., Pauls, D. L., Kurlan, R., Kidd, K. K., Pakstis, A. J., … Gelernter, J. (1996). Linkage disequilibrium between an allele at the dopamine D4 receptor locus and Tourette syndrome, by the transmission-disequilibrium test. American Journal of Human Genetics, 59(3), 644–652. Kazuhiko, N., Yoshimoto, S., Noriyoshi, T., Yasuhide, I., Katsuaki, S., Ayyappan, A., … Norio, M. (2009). An association study of monoamine oxidase A (MAOA) gene polymorphism in methamphetamine psychosis. Neuroscience Letters, 455, 120–123.

Lung, F. W., Tzeng, D. S., Huang, M. F., & Lee, M. B. (2011). Association of the MAOA promoter uVNTR polymorphism with suicide attempts in patients with major depressive disorder. BMC Medical Genetics, 12, 74. Ozelius, L., Hsu, Y. P., Bruns, G., Powell, J. F., Chen, S., Weyler, W., … Breakefield, X. O.. (1988). Human monoamine oxidase gene (MAOA): Chromosome position (Xp21-p11) and DNA polymorphism. Genomics, 3(1), 53–58. Pauls, D. L., Cohen, D. J., Heimbuch, R., Detlor, J., & Kidd, K. K. (1981). Familial pattern and transmission of Gilles de la Tourette syndrome and multiple tics. Archives of General Psychiatry, 38(10), 1091–1093. Price, R. A., Kidd, K. K., Cohen, D. J., Pauls, D. L., & Leckman, J. F. (1985). A twin study of Tourette syndrome. Archives of General Psychiatry, 42(8), 815–820. Robertson, M. M., Eapen, V., & Cavanna, A. E. (2009). The international prevalence, epidemiology, and clinical phenomenology of Tourette syndrome: A cross-cultural perspective. Journal of Psychosomatic Research, 67(6), 475–483. Sabol, S. Z., Hu, S., & Hamer, D. (1998). A functional polymorphism in the monoamine oxidase A gene promoter. Human Genetics, 103(3), 273–279. Sjoberg, R. L., Ducci, F., Barr, C. S., Newman, T. K., Dell’osso, L., Virkkunen, M., & Goldman, D. (2008). A non-additive interaction of a functional MAO-A VNTR and testosterone predicts antisocial behavior. Neuro- Psychopharmacology, 33(2), 425–430. Tarnok, Z., Ronai, Z., Gervai, J., Kereszturi, E., Gadoros, J., Sasvari-Szekely, M., & Nemoda, Z. (2007). Dopaminergic candidate genes in Tourette syndrome: Association between tic severity and 3′ UTR polymorphism of the dopamine transporter gene. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics, 144B(7), 900–905. Yoon, D. Y., Rippel, C. A., Kobets, A. J., Morris, C. M., Lee, J. E., Williams, P. N., … Singer, H. S. (2007). Dopaminergic polymorphisms in Tourette syndrome: Association with the DAT gene (SLC6A3). American Journal of Medical Genetics Part B: Neuropsychiatric Genetics, 144B(5), 605–610. Zsofia, N., Anna, S., & Maria, S. (2011, August). Psychopathological aspects of dopaminergic gene polymorphisms in adolescence and young adulthood. Neuroscience and Biobehavioral Reviews, 35(8), 1665–1686.