Analysis of the monoamine oxidase A (MAOA) gene in bipolar affective disorder by association studies, meta-analyses, and sequencing of the promoter.

Monoamine oxidases catalyse the oxidative degradation of biogenic amines including neurotransmitters such as noradrenaline, dopamine, and 5-hydroxytryptamine (5-HT). Three groups have reported positive associations of the monoamine oxidase A (MAOA) gene with bipolar affective disorder although other studies have been negative. In an extension of a previous study [Rubinsztein et al., 1996: Human Molec Genet 5:779-782] we report association studies of MAOA polymorphic markers and affective disorders. The polymorphisms comprised a CA-repeat microsatellite in intron 2 and a Fnu4HI G/T silent polymorphism at position 941 of the cDNA sequence. No significant differences were found when the control allele frequencies were compared with those in bipolar, unipolar, or combined bipolar + unipolar groups. Meta-analyses were then performed to include the data of all published studies using the MAOA microsatellite and Fnu4HI polymorphisms. Separate meta-analyses were performed for Caucasian and Japanese studies, as allele frequencies of the microsatellite in these populations were markedly different. Associations of bipolar affective disorder in pooled male and female groups were found with the MAOA microsatellite in both the Caucasian (P < 0.02) and the Japanese (P < 0.02) meta-analyses. In view of these positive associations, and as previous results have shown that coding variants do not account for the normal population variation in MAOA activity, over 1,300 bp of the promoter were sequenced in 22 bipolar cases and 1 control. A novel polymorphic promoter variable number of tandem repeats (VNTR) located approximately 1,200 bp upstream from the translation start site was demonstrated. However, there was no association of this promoter VNTR with affective disorder. These results suggest that there may be functional variants in other regions of the MAOA gene or neighbouring genes that affect bipolar affective disorder risk.     

Association analysis between mood disorder and monoamine oxidase gene

To ascertain whether mood disorders, including bipolar and unipolar, are genetically associated with the monoamine oxidase A (MAOA) or monoamine oxidase B (MAOB) gene in the Chinese population, 132 cases of mood disorder and 88 normal controls were genotyped for the MAOA(CA)n, MAOB(GT)n, and MAOB(TG)n loci by the method of amplification fragment length polymorphism. Among 132 cases with mood disorder, eight alleles (size: 112-126 bp) of locus MAOA(CA)n, 12 alleles (size: 168-198 bp) of locus MAOB(GT)n, and nine alleles (size: 195-213 bp) of locus MAOB(TG)n were observed. Comparison of the allele frequency of the three loci showed no difference between mood disorder cases and normal controls on average. When each group was stratified into several subgroups, significant differences were found. On the MAOA(CA)n locus, the frequency of 116 bp allele was higher in the female bipolar disorder cases (0.2581) compared with that in the female unipolar disorder patients (0.1154) (Z=2.15, p<0. 05). On the MAOB(GT)n locus, the frequency of 180 bp allele was higher in bipolar disorder patients (0.1579) than that in normal controls (0.0678) (Z=2.05, p<0.05). The frequency of this allele was even higher in female bipolar disorder patients (0.1719) than that in female normal controls (0.0541). On the MAOB(TG)n locus, the frequency of 205 bp allele was higher in female bipolar disorder patients (0.6406) than that in female normal controls (0.4375) (Z=2. 17, p<0.05). For the unipolar disorder patients, the frequency of this allele was higher in female cases (0.5222) than that in male cases (0.1818) (Z=3.49, p<0.05). As for association studies, significant association between bipolar disorder and MAOB gene was detected. For the 180 bp allele of MAOB(GT)n, the relative risk (RR) of biploar versus normal control was 2.58 (p<0.05), and the RR of female bipolar disorder versus female normal control was 3.63 (p<0. 05). For the 205 bp allele of MAOB(TG)n, the RR of female bipolar disorder versus female normal control was 2.29 (p<0.05). Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:12-14, 2000.     

No association of the tryptophan hydroxylase gene with bipolar affective disorder,unipolar affective disorder,or suicidal behaviour in major affective disorder

Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the synthesis of 5-hydroxytryptamine (5-HT). An association study in bipolar affective disorder I or unipolar major affective disorder was performed by using a Bfa I restriction site polymorphism within intron 7 of the tryptophan hydroxylase gene. A total of 118 bipolar, 125 unipolar, and 437 control subjects were used in the study (1:3.7 bipolar:control, 1:3.5 unipolar:control). There were no significant differences in TPH allele or genotype frequencies between the affective disorder and control groups. In addition, bipolar and/or unipolar subjects with or without a history of suicide attempts were compared for the TPH polymorphism. No significant differences were found between suicidal and nonsuicidal groups in major affective disorder, in contrast to a previous study suggesting an association of this polymorphism with a history of suicide attempts among alcoholic violent offenders. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 81:245–247, 1998. © 1998 Wiley-Liss, Inc.     

An association between a polymorphism of the tryptophan hydroxylase gene and aggression in schizophrenia and schizoaffective disorder

Serotonergic pathways have been implicated in impulsive and aggressive behavior. Polymorphisms in the regulatory region of the serotonin transporter (5-HTT), in intron 7 of the tryptophan hydroxylase (TPH) gene and in the MAOA gene were previously reported to be associated with mood and anxiety disorders, impulsivity and aggression. In this study, we analyzed these polymorphisms in men and women with schizophrenia or schizoaffective disorder (n = 84) who met our criteria for violence (history of two or more assaults on others) or nonviolence (no history of either assaultive or threatening behavior). In males, a modest association between TPH genotype and history of violence (chi-square test = 6.703, degrees of freedom = 2, P = 0.035) was not statistically significant after correction for multiple comparisons (corrected P = 0.21). The TPH L allele was more frequent in violent males (chi-square = 5.323, degrees of freedom = 1, P = 0.021) but this difference also failed to withstand correction (corrected P = 0.126). No significant associations were found for either the 5-HTT or MAOA polymorphisms in males or females. These results tend to support previous reports by New et al. (1996; 1998) of an association between the TPH L allele and impulsive aggression in males with personality disorder, but larger studies are needed.     

Monoamine oxidase genes polymorphisms and mood disorder

We investigated a genetic association between mood disorders (bipolar and unipolar) and the alleles of monoamine oxidase (MAO) A and B (MAOA and MAOB). One hundred and twelve unrelated Japanese patients (60 bipolar, 52 unipolar) and 100 controls were genotyped for three markers of MAOA and for one marker of MAOB. No statistically significant difference in the distribution of the alleles existed between cases and controls. Therefore, our results did not support the involvement of the alleles at MAOA and MAOB in the etiology of mood disorder. Am. J. Med. Genet. 74:494–496, 1997. © 1997 Wiley-Liss, Inc.     

No association of a functional polymorphism in the dopamine D2 receptor promoter region with bipolar or unipolar affective disorders

The dopaminergic system, along with the serotonergic and noradrenergic systems, has been implicated in the etiology of mood disorders. An association study of a functional variant in the promoter region of the dopamine D2 receptor (DRD2) with bipolar affective disorder I or unipolar major affective disorders was performed. Variable expression of the DRD2 gene in vitro has been shown with this promoter polymorphism. One hundred and thirty-one unrelated bipolar patients, 128 unrelated unipolar patients, and 262 controls were used in the study. There were no significant differences in DRD2 allele or genotype frequencies between the affective disorder and control groups. These results do not support a major role for the DRD2 gene in the etiology of either bipolar or unipolar affective disorders. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 81:385–387, 1998. © 1998 Wiley-Liss, Inc.     

Bipolar disorder and the serotonin transporter gene: a family-based association study

BACKGROUND: The human serotonin transporter gene (5-HTT) is a strong candidate for involvement in the pathogenesis of mood disorders. Two common polymorphisms have been identified in the gene: a VNTR in intron 2 and a functional deletion/insertion in the promoter region. In previous studies we proposed that allele 12 of the VNTR might increase susceptibility for bipolar disorder. METHODS: We have genotyped 122 parent-offspring trios of British Caucasian origin where the proband had DSM-IV Bipolar I disorder (BPI). The results were analysed with the transmission/ disequilibrium test (TDT), which examines whether particular alleles are preferentially transmitted from heterozygous parents to affected offspring. RESULTS: The 12 repeat in the VNTR in intron 2 was transmitted 72 times and not transmitted 56 times (chi2 = 2.0, 1 df, P = 0.16). If we exclude 24 families in which the proband was a case in our published case-control studies (Collier et al. 1996a; Rees et al. 1997), the excess transmission of allele 12 reaches conventional levels of statistical significance: chi2 = 3.85, 1 df, P < 0.05. The deletion/insertion polymorphism in the promoter region was not associated with BPI: 66 parents transmitted the inserted (L) allele and 59 parents transmitted the deleted (S) allele (chi2 = 0.39, 1 df, P = 0.53). CONCLUSIONS: The 12 repeat of the VNTR in intron 2 of the serotonin transporter gene might be a susceptibility factor in bipolar affective disorder. The genetic effect, if true, is likely to be small, and requires confirmation in further studies using parental controls.     

Gene-gene interaction between MAOA and COMT in suicidal behavior

Several lines of evidence suggest that suicidal behavior is associated with altered noradrenergic neurotransmission. Noradrenaline (NA) is catabolized by monoamine oxidase A (MAOA) and cathecol-O-methyl transferase (COMT). We hypothesized that the genes encoding MAOA and COMT might contain genetic variation conferring increased risk for attempted suicide. In order to test this hypothesis, we genotyped the 941T > G and the promoter VNTR polymorphisms in the MAOA gene and the Val 108/158 Met COMT polymorphism in 305 families with at least one member having bipolar disorder (BD). No association with history of suicide attempt was found either in the MAOA polymorphisms (VNTR:LRS = 1.90, d.f. = 1, p = 0.16; 941T > G:LRS = 1.39, d.f. = 1, p = 0.23), or with the Val 158 Met polymorphism (LRS = 1.61, d.f.=1, p = 0.20). When we performed the haplotype analysis for MAOA gene, we found no association between suicide attempt and haplotype distribution (LRS = 3.07, d.f. = 2, p = 0.21). As both genes are involved in degrading noradreanline, we also tested the hypothesis of epistasis between MAOA polymorphisms and Val158Met, however, no additive effect was found in conferring risk for suicide attempt. These findings suggest that MAOA and COMT genes may not influence suicidal behavior in patients with bipolar disorder.     

Prevalence and clinical correlates of residual depressive symptoms in bipolar II disorder

BACKGROUND: Most patients with unipolar and bipolar I disorder have residual symptoms, despite successful treatment. The appraisal of subsyndromal symptomatology has important implications for pathophysiological models of disease and relapse prevention. Residual symptoms in bipolar II disorder were studied insufficiently. The study of residual symptoms in bipolar II disorder is important, because many depressed outpatients may suffer from it and because bipolar II disorder may be distinct from type I. The study aims were to assess the prevalence and clinical correlates of persistent residual depressive symptoms in bipolar II disorder. METHODS: 138 consecutive patients with bipolar II disorder and 83 unipolar disorder outpatients, presenting for major depressive episode treatment in private practice, were interviewed with the Structured Clinical Interview for DSM-IV Axis I Disorders - Clinician's Version. Study variables were persistent (more than 2 years) residual depressive symptoms, age, gender, age at onset, illness duration, recurrences, axis I comorbidity, severity, psychotic, melancholic and atypical features. RESULTS: The prevalence of residual depressive symptoms was 44.9% in bipolar II disorder and 43.3% in unipolar disorder. Residual depressive symptoms in bipolar II and unipolar disorders were significantly and positively associated with illness duration and recurrences. CONCLUSIONS: Persistent residual depressive symptoms were common in bipolar II disorder. Residual unipolar and bipolar II depressive symptoms were related to duration of illness and number of recurrences. Reducing these variables could reduce and prevent residual symptoms. A mechanism of kindling (more mood episodes leading to worse outcome) could be that of leaving a larger and larger amount of residual symptoms after the acute episode has subsided.     

Family-based association study between bipolar disorder and DRD2, DRD4, DAT,and SERT in Sardinia

Association analysis of candidate genes may represent a strategy for clarifying the genetic components involved in bipolar disorder. Polymorphism at dopamine receptor genes DRD2, DRD4, and dopamine and serotonin transporter genes (DAT, SERT) has been used in previous association studies. Some authors have reported positive association between certain alleles and bipolar disorder, using the case-control design. In this family-based association study of DRD2, DRD4, DAT, and SERT, the distribution of parental nontransmitted alleles was compared with that of alleles transmitted to 53 Sardinian probands suffering from bipolar disorder. The transmission disequilibrium test (TDT) was used to detect any disproportionate transmission of alleles by heterozygous parents to affected children. No differences were found between the allele distribution of polymorphisms at DRD2, DRD4, DAT, and SERT in probands and parental nontransmitted chromosomes. TDT did not reveal any difference between transmitted and nontransmitted alleles. Our results do not support the hypothesis of a role for DRD2, DRD4, DAT, or SERT in bipolar disorder. Previously reported positive associations between DRD2 or SERT and bipolar disorder were conceivably due to stratification dependent on the case-control design, even though our sample might have failed to detect small associations due to limited power. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:522–526, 1999. © 1999 Wiley-Liss, Inc.     

Psychotic symptoms in pediatric bipolar disorder and family history of psychiatric illness

BACKGROUND: Few studies have examined the specificity and non-specificity in patterns of familial loading for presentation of psychotic symptoms in pediatric bipolar disorder (BP). METHODS: Diagnostic assessment of 263 pediatric BP probands included lifetime history of psychotic symptoms as well as longitudinal follow-up; family history of psychiatric illness was determined for 1st degree relatives. RESULTS: Pediatric BP probands with lifetime history of psychosis had a higher percentage of positive family history of anxiety disorders and suicide attempts as compared to probands with no history of psychosis. DISCUSSION: Familial loading for a spectrum of internalizing disorders is associated with presentation of psychotic symptoms in pediatric BP.     

Antidepressant monotherapy in pre-bipolar depression; predictive value and inherent risk

OBJECTIVE: To identify specific treatment-emergent symptoms in response to antidepressant therapy in depression preceding bipolar disorder. METHODS: Retrospective chart review of response to antidepressants in "pre-bipolar" depression, compared to a matched unipolar sample. RESULTS: Family history of completed suicide (p=0.0003) and bipolar disorder (p=0.004) were more common in the pre-bipolar subgroup. Earlier age of onset of diagnosed depression (p=0.005) as well as even earlier episodes of untreated retrospectively diagnosed major depression (p<0.0001) were associated with a future bipolar course. The pre-bipolar group was less likely to respond to antidepressant treatment (p=0.009). Treatment-emergent "mixed" symptoms (two or more symptoms of DSM IV mania, mood lability, irritability/rage with co-existing depression) and in particular, "serious symptoms" (treatment emergent or increased agitation, rage or suicidality) occurred more commonly in the bipolar group. The two variables that best accounted for the between-group differences in logistic regression, were early age at first symptoms of depression and treatment-emergent agitation. CONCLUSIONS: Family history of completed suicide and/or bipolar disorder, early onset of depressive symptoms as well as treatment-emergent "mixed" symptoms are common in depression preceding the diagnosis of bipolar disorder.     

Subjective life satisfaction and objective functional outcome in bipolar and unipolar mood disorders: a longitudinal analysis

BACKGROUND: Quality of life (QOL) has gained increasing attention as an important yet underappreciated component of functional outcome in mood disorders. In particular, the relationship between subjective life satisfaction and objective measures of psychosocial adjustment has not been well-studied. The goal of the present study was to examine the longitudinal associations between subjective life satisfaction and objective functional outcome among individuals with bipolar and unipolar mood disorders. METHOD: One hundred fifty-seven mood disordered subjects were assessed at index hospitalization for bipolar mania (n=35), unipolar psychotic depression (n=27), or unipolar nonpsychotic depression (n=95). All were prospectively followed up three times, at approximately 2, 4.5 and 7-8 years. Global outcome, work performance, social adjustment, recurrent depressive episodes, and dimensions of life satisfaction were assessed by semi-structured interviews using standardized ratings. RESULTS: Subjective life satisfaction strongly paralleled global functioning, work performance and social adjustment at each follow-up for patients with unipolar nonpsychotic depression, but not bipolar disorder or unipolar psychotic depression. Depressive symptoms and objective functional impairment contributed to poor QOL in most domains, independent of illness chronicity, medication use, or affective disorder subtype. LIMITATIONS: Findings might have differed had a different QOL measure been used, although the present measure showed concurrent validity with a previously used instrument. Sample sizes for the bipolar and psychotic depression groups were sufficient to detect moderate, but not small, correlations between objective functioning and subjective QOL. CONCLUSIONS: Recurrent depression remains a substantial contributor to poor life satisfaction across affective disorder subtypes. Subjective QOL in bipolar and unipolar psychotic depression patients may not accurately reflect objective functional outcome status, potentially due to diminished insight, demoralization, or altered life expectations over time.     

强迫症药物疗效与六个功能基因的分子遗传药理学研究

目的　探讨与5-羟色胺系统和多巴胺系统有关的6个基因(5-羟色胺2A受体基因、5-羟色胺转运体基因、多巴胺D2受体基因、多巴胺D4受体基因、儿茶酚胺氧位甲基转移酶基因、单胺氧化酶A基因)与强迫症药物疗效之间是否存在关联。方法　收集了113个强迫症核心家系,对强迫症患者给予5-羟色胺回吸收抑制剂治疗,采用Yale-Brown强迫量表在治疗8周前后进行评定,按Yale-Brown强迫量表评分分为有效组和无效组。采用限制性片段长度多态性和可变数串联重复序列多态性技术对有效组和无效组的强迫症家系在6个基因的7个位点上进行传递不平衡检测。结果　未发现6个基因与不同药效的强迫症家系之间存在关联,但发现有效组和无效组在5-羟色胺2A受体基因-1438G/A位点基因型频率存在差异,无效组有更多的纯合子(χ2=4.69,P=0.03)。结论　5-羟色胺2A受体基因可能和强迫症药物治疗效果有关。     

Clinical variables related to antidepressant-induced mania in bipolar disorder

BACKGROUND: The development of mania or hypomania during antidepressant treatment is a serious complication of the clinical management of bipolar disorder (BP). The primary aim of this study was to evaluate the clinical variables related to antidepressant-induced mania or hypomania (AIM) in patients with BP. METHODS: DSM-IV BP-I or BP-II patients who had had at least one depressive episode treated with antidepressants were considered. Patients were subdivided into two groups according to the presence (n = 30) or absence (n = 106) of manic or hypomanic episodes occurring during antidepressant treatment. Possible predictive clinical variables of AIM were considered: gender, diagnostic subtype, age at onset, duration of illness, duration of untreated illness, type of antidepressant administered, number of previous spontaneous hypomanic or manic episodes, number of previous depressive episodes, presence of lifetime suicide attempts, presence of mood stabilizer treatments, presence of psychotic symptoms during spontaneous episodes, family history for psychiatric disorders in first degree relatives. Data were compared between the two groups, with (AIM+) and without (AIM-) antidepressant-induced mania, using Student's t tests and chi-square tests. RESULTS: The lack of mood stabilizer treatments during antidepressant therapy (chi-square = 37.602, df = 1, p < 0.001) and the exposure to tricyclic antidepressants (chi-square = 4.901, df = 1, p < 0.05) resulted significantly associated to the development of AIM. LIMITATIONS: This study was not done under controlled conditions and the relatively small sample studied warrants further replications. CONCLUSIONS: These results point out the risk of mania induction associated to the use of tricyclic antidepressants in BP patients, mainly in absence of adequate mood stabilizers.     

MAOA promoter polymorphism and attention deficit hyperactivity disorder (ADHD) in indian children.

Attention deficit hyperactivity disorder (ADHD) is a highly disabling, early onset childhood neurobehavioral disorder with a higher occurrence in boys as compared to girls. Pharmacological and molecular genetic studies have revealed the influence of dopaminergic and serotonergic systems in the etiology of the disorder. Monoamine oxidase A (MAOA) is a mitochondrial enzyme that regulates the dopaminergic signals in the pre-synaptic region. Polymorphism in the promoter region of the MAOA gene, which comprises of 30 bp repeats with repeat number varying between 2.5, 3.5, 4.5, and 5.5, has been shown to be associated with various neurobehavioral disorders including ADHD. This is the first study on Indian ADHD cases to validate an association between transmission of MAOA promoter polymorphism and risk of ADHD. We have analyzed the MAOA promoter polymorphism in a group of ADHD probands, their parents and ethnically matched controls by UNPHASED. Our findings indicate significant difference in the frequency of 3.5 repeat allele (P = 0.02) between cases and controls and preferential transmission of the short allele (3.5 repeat) from mothers to male ADHD probands (P = 0.005). We conclude that the short 3.5 repeat allele of the MAOA-u VNTR is probably associated with ADHD in our population and could be the reason for making boys prone to ADHD as compared to girls.