D2S2944 identifies a likely susceptibility locus for recurrent, early-onset, major depression in women

The Genetic Side of the Mood: A Scientometric Review of the Genetic Basis of Mood Disorders

Mood disorders are highly heritable psychiatric disorders. Over the years, many genetic polymorphisms have been identified to pose a higher risk for the development of mood disorders. To overview the literature on the genetics of mood disorders, a scientometric analysis was performed on a sample of 5342 documents downloaded from Scopus. The most active countries and the most impactful documents in the field were identified. Furthermore, a total of 13 main thematic clusters emerged in the literature. From the qualitative inspection of clusters, it emerged that the research interest moved from a monogenic to a polygenic risk framework. Researchers have moved from the study of single genes in the early 1990s to conducting genome-wide association studies around 2015. In this way, genetic overlaps between mood disorders and other psychiatric conditions emerged too. Furthermore, around the 2010s, the interaction between genes and environmental factors emerged as pivotal in understanding the risk for mood disorders. The inspection of thematic clusters provides a valuable insight into the past and recent trends of research in the genetics of mood disorders and sheds light onto future lines of research.

[Risk factors and prevention of recurrent dynamics of depression]

The existing literature in the field demonstrates that in the majority of cases depressive disorder has a recurrent course that resulted in negative consequences: an increase in a number of chronic and marked episodes, a higher risk of suicide and stable cognitive deficit. An analysis of predictors promoting the formation of recurrent depressive disorder allows an identification of a constellation of biological, psychological, therapeutic, social factors which should be taken into account in the choice of methods of prevention of the next episode of depression. Currently, the prolonged supporting psychopharmacotherapy, including antidepressant therapy, is a main tactics in the prevention of recurrent dynamics of depressive disorder though its efficacy is understudied.

Serotonin transporter gene: a new polymorphism may affect response to antidepressant treatments in major depressive disorder

BACKGROUND AND OBJECTIVES

Several gene variants have been related to major depressive disorder (MDD) treatment outcomes; however, few studies have investigated a possible different effect on pharmacotherapy and brief psychotherapy response.

METHODS

A total of 137 MDD patients were randomized to either interpersonal counseling (IPC; n = 40) or antidepressant pharmacological treatment (n = 97). Outcomes were remission, response, and symptom improvement at week 8. Five genetic variants were investigated (5HTR2A rs6314, BDNF rs6265, SLC6A4 rs8076005, CREB1 rs2253206, and TPH2 rs11179023) as possible modulators of outcomes.

RESULTS

The LC6A4 rs8076005 AA genotype and A allele were associated with response rate in the antidepressant group (p = 0.015 and 0.005, respectively) and in the whole sample (p = 0.03 and 0.02, respectively). In the IPC group a non-significant trend in the same direction was observed. The TPH2 rs11179023 A allele showed a marginal association with symptom improvement in the IPC group only. Other gene variants did not impact on outcomes in any treatment group.

CONCLUSION

Our study suggests that rs8076005 in the SLC6A4 gene may be a modulator of antidepressant response, especially when pharmacological treatment is used.

Are there depression and anxiety genetic markers and mutations? A systematic review

BACKGROUND

Genetic factors may encourage or even cause the occurrence of mood disorders such as anxiety and/or depression. However, despite the significant amount of work and sophisticated technology is not fully elucidated which genes or regions of nuclear or mitochondrial DNA, or which types of genetic changes, alone or in combination, can represent reliable genetic markers of anxiety and/or depression.

OBJECTIVE

To identify whether there are genetic changes that can cause depression or anxiety and if there are genetic markers that can be used to detect these changes.

METHODS

A systematic review of 01.01.2004 to 03.28.2014 was held by VHL (Virtual Health Library). The search was performed with the descriptors ׳׳anxiety׳׳, ׳׳depression׳׳, "mutation" and "genetic markers׳׳. The selected articles were indexed in MEDLINE. The information pertinent to the study was selected, categorized and analyzed. Of the 374 articles found, 29 met the eligibility criteria.

RESULTS

FMR1 gene polymorphisms, dopaminergic (DAT, DRD, COMT), serotonin (5-HTTLPR, HTR1A, HTR2A), interleukins, MCR1, HCN (potassium channel), neurorregulinas, GABAergic (GABA, GAD, DBI) DBI, GABA (Gabra) receptors and GAD genes (GAD1, GAD2) appear to contribute to generate condition of depression or anxiety like. Mutations in mitochondrial DNA in 124pb allele of D2S2944 in ofil 1 and 2 loci of chromosomes 4 and 7, respectively, and the chromosomes 8p, 17p and 15q appear to be associated with the origin of depression or anxiety.

CONCLUSION

Some studies show only associations with one of the disorders, mainly anxiety. Few have shown association with both simultaneously. Other studies showed specific association of gender, or even specific ethnic groups. It was noticed, controversies over certain markers. Interesting results were observed in combination of changes, especially in cases of SNPs, indicating that perhaps this is the most appropriate way to find reliable markers.

European Group for the Study of Resistant Depression (GSRD)--where have we gone so far: review of clinical and genetic findings

The primary objective of this review is to give an overview of the main findings of the European multicenter project "Patterns of Treatment Resistance and Switching Strategies in Affective Disorder", performed by the Group for the Study of Resistant Depression (GSRD). The aim was to study methodological issues, operational criteria, clinical characteristics, and genetic variables associated with treatment resistant depression (TRD), that is failure to reach response after at least two consecutive adequate antidepressant trials. The primary findings of clinical variables associated with treatment resistance include comorbid anxiety disorders as well as non-response to the first antidepressant received lifetime. Although there is a plethora of hints in textbooks that switching the mechanism of action should be obtained in case of nonresponse to one medication, the results of the GSRD challenge this notion by demonstrating in retrospective and prospective evaluations that staying on the same antidepressant mechanism of action for a longer time is more beneficial than switching, however, when switching is an option there is no benefit to switch across class. The GSRD candidate gene studies found that metabolism status according to cytochrome P450 gene polymorphisms may not be helpful to predict response and remission rates to antidepressants. Significant associations with MDD and antidepressant treatment response were found for COMT SNPs. Investigating the impact of COMT on suicidal behaviour, we found a significant association with suicide risk in MDD patients not responding to antidepressant treatment, but not in responders. Further significant associations with treatment response phenotypes were found with BDNF, 5HTR2A and CREB1. Additional investigated candidate genes were DTNBP1, 5HT1A, PTGS2, GRIK4 and GNB3.

Gender-specific role of the protein tyrosine phosphatase receptor type R gene in major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is a common, chronic, and recurrent mental disease affecting millions of individuals worldwide. The precise mechanism by which the illness is developed remains unknown, but it has been accepted that a genetic component is very likely to be involved. Studies of the pathogenesis of MDD have implicated a reduced activity of the extracellular regulated kinase (ERK) signaling system. Protein tyrosine phosphatase, receptor type R (PTPRR) is a key negative regulator of the ERK signaling pathway and its expression is regulated by androgen. Therefore, it is worth testing whether the PTPRR gene could confer a risk of MDD.

METHODS

We genotyped 16 SNPs in the PTPRR locus with the MALDI-TOF-MS-based genotyping protocol in 517 patients with MDD and 455 controls among a Chinese Han population. The UNPHASED program was applied to analyze the genotyping data.

RESULTS

Of the 16 SNPs selected, rs1513105 was the only one showing allelic association (χ2=9.019, p=0.0027) and genotypic association (χ2=8.813, df=2, p=0.012), of which the rs1513105(C) allele was associated with an increased risk of MDD (OR=1.331, 95% CI 1.104-1.604), but the rs1513105 association resulted mainly from female subjects (χ2=12.35, p=0.00044 for allelic association; χ2=11.26, df=2, p=0.0036 for genotypic association).

LIMITATIONS

Replication and functional study may be required to draw a firm conclusion.

CONCLUSIONS

Our results suggest that the PTPRR gene may play a role in conferring risk of MDD in the female subjects.

Replacement of homologous mouse DNA sequence with pathogenic 6-base human CREB1 promoter sequence creates murine model of major depressive disorder

Major depressive disorder (MDD) is a leading cause of disability worldwide. Families with recurrent, early-onset MDD (RE-MDD), a severe, familial form of MDD, have provided an important resource for identifying and characterizing genetic variants that confer susceptibility to MDD and related disorders. Previous studies identified a rare, highly penetrant A(-115)G transition within the human CREB1 promoter that reduced promoter activity in vitro and was associated with depressive disorders in RE-MDD families. The development of an etiology-based recombinant animal model for MDD would facilitate the advancement of our limited understanding of the pathophysiology of MDD, as well as the development of improved treatments. Here we report the construction and initial characterization of a congenic mutant C57BL/6NTac mouse model that carries the human pathogenic sequence at the homologous position of the mouse Creb1 promoter. The recombinant strain exhibited decreases in reproductive capacity and pup survival that may be related to increased infant mortality observed in RE-MDD families; enlargement of the cerebral ventricles; reduced levels of CREB protein in the mouse cerebral cortex, as predicted from transfection experiments employing the pathogenic human CREB1 promoter; and alterations in two standardized behavioral tests, the forced swim and marble burying tests. These initial findings support the pathogenicity of the human A(-115)G promoter variant, and invite further characterization of this etiology-based recombinant animal model for MDD. Human promoter variants that have highly penetrant effects on disease expression provide an attractive opportunity for creating etiology-based mouse models of human diseases, with minimal disruption of the mouse genome.

Factors associated with recurrent depression: a prospective study in family practice

BACKGROUND

Depression has a high rate of recurrence. Finding the variables that predict which patients are at higher risk of experiencing a recurrent episode of depression would benefit an individual patient.

OBJECTIVE

To determine the factors associated with recurrent depression >12 months.

METHODS

Consecutive patients (N = 1094), aged 18-75 years, were recruited from 23 family practices across Estonia. The patients were followed up at 6- and 12-month intervals as suggested in the PredictD study. Depression was assessed using the Composite International Diagnostic Interview. Each participant filled in a questionnaire to assess their risk factors for depression.

RESULTS

Major depression was diagnosed in 13% of the patients. Twenty-eight per cent of the depressed patients had a recurrent episode of depression 12 months later. The odds of having recurrent depression were significantly higher for patients who had a history of drug abuse, odds ratio (OR) 7.48 [95% confidence interval (CI) = 1.42-39.43), for patients who had experienced discrimination, OR 2.92 (95% CI = 1.05-8.11) and for patients with a history of childhood abuse, OR 1.58 (95% CI = 1.05-2.38).

CONCLUSIONS

One-third of the patients developed recurrent depression. Drug abuse, discrimination and childhood abuse predicted recurrent depression. These factors should be taken into consideration by family doctors when managing patients with depression.

Effects of the A(-115)G variant on CREB1 promoter activity in two brain cell lines: Interactions with gonadal steroids

Major depressive disorder (MDD) is a leading contributor to disease burden worldwide. Previous genetic studies have revealed significant evidence of linkage of the CREB1 region to mood disorders among women from families with recurrent, early-onset MDD (RE-MDD), a severe and familial subtype of MDD. Systematic resequencing of the CREB1 gene in affected members of these families has identified rare sequence variants at positions -656 and -115 that appear to cosegregate with unipolar mood disorders in two large multigenerational families and three small nuclear families, respectively. Results from previous transfection experiments that employed constructs containing the wild-type or variant CREB1 promoters coupled to a reporter gene support the hypothesis that the A(-656) allele contributes to the development of MDD in women by selectively increasing the activity of the CREB1 promoter in brain cell lines exposed to 17 β-estradiol. Analogous transfection experiments described in the current study revealed that the G(-115) promoter variant reduced promoter activity in CATH.a neuronal cells regardless of the hormonal environment, consistent with the observation that increased risk for unipolar mood disorders conferred by this allele was not limited by sex. The effects of CREB1 promoter variants on promoter activity, their influence on the development of mood disorders and related clinical features, and the interaction of their phenotypic expression with sex seem likely to be complex and allele-specific rather than a general property of the CREB1 locus. © 2010 Wiley-Liss, Inc.

Genetic linkage of region containing the CREB1 gene to depressive disorders in families with recurrent, early-onset, major depression: a re-analysis and confirmation of sex-specific effect

A previously published model-free linkage analysis of chromosome 2q33-35, highlighted by previous case-control studies and supported by within-family analyses employing the transmission disequilibrium test, revealed evidence of sex-specific linkage of the CREB1-containing region of 2q to unipolar mood disorders among women in 81 recurrent, early-onset, major depressive disorder (RE-MDD) families. Since it has been reported that the LODPAL program from S.A.G.E. v.4.0 used to conduct this previous linkage analysis suffers from an increased type I error rate that is exacerbated by covariates such as sex, we re-analyzed the evidence for this sex-specific linkage result using a simulation approach to estimate the empirical significance of our previous results. The results continue to support sex-specific linkage of the CREB1 region to mood disorders among women from families with RE-MDD. Moreover, these results have been supported by a host of additional published findings that implicate sequence variations in CREB1 in the sex-dependent development of syndromic mood disorders, as well as related clinical features and disorders.

Effects of the G(-656)A variant on CREB1 promoter activity in a neuronal cell line: interactions with gonadal steroids and stress

Major depressive disorder (MDD) constitutes a major public health problem worldwide and affects women twice as frequently as men. Previous genetic studies have revealed significant evidence of linkage of the cAMP-responsive element-binding protein 1 (CREB1) gene region (2q33-35) to mood disorders among women from families with recurrent, early-onset MDD (RE-MDD), a severe and familial subtype of MDD. A rare G-to-A transition at position -656 in the CREB1 promoter co-segregates with mood disorders in women from these families, implicating CREB1 as a sex-related susceptibility gene for unipolar mood disorders. In the current study, the functional significance of the CREB1 promoter variant was determined using transfection experiments that employed plasmid constructs containing the wild-type or variant CREB1 promoters coupled to a reporter gene. The results support the hypothesis that the A(-656) allele contributes to the development of MDD in women through selective alteration of CREB1 promoter activity by female gonadal steroids in noradrenergic neuronal cells. Furthermore, exaggeration of these effects during a simulated stress condition may be relevant to reported gene-environment interactions that contribute to the emergence of MDD in clinical populations.

Familiality of major depressive disorder and patterns of lifetime comorbidity. The NEMESIS and GenMood studies. A comparison of three samples

BACKGROUND

Major depressive disorder (MDD) aggregates in families and is associated with high rates of lifetime axis-I comorbidity. This study examined whether familiality of MDD is associated with the presence of specific comorbid disorders, which might be an important factor to be taken into account in MDD treatment and research into MDD etiology.

METHODS

A population sample was divided into subjects with familial (f-MDD; n=432) and nonfamilial MDD (nf-MDD; n=454). Since, more comorbidity was expected in clinical cases, a clinical sample with f-MDD (n=120) was also studied. Subjects were assessed with the Composite International Diagnostic Interview and family history methods. Binary logistic regression analyses were carried out to examine the influence of familiality of MDD on comorbidity. Analyses were adjusted for potential confounders, including MDD characteristics such as severity and age of onset.

RESULTS

Dysthymia, anxiety disorders, and alcohol use disorders were significantly more prevalent in subjects with f-MDD than in subjects with nf-MDD. Clinical f-MDD was associated with more anxiety disorders and fewer alcohol use disorders than population f-MDD. After adjustment for MDD characteristics including age at onset, severity, and disease course, comorbid disorders remained more prevalent in f-MDD than in nf-MDD.

LIMITATIONS

The instruments used in the population and the clinical samples were not identical, however, they were comparable to a substantial degree.

CONCLUSIONS

F-MDD, especially in clinical cases, appears to increase the risk of development of comorbid disorders, regardless of MDD characteristics. The link between familiality and comorbidity is important because it will aid a better understanding of the MDD phenotype, and it contributes to planning of effective treatment and to molecular genetic studies.

Psychometric perspectives on diagnostic systems

The author identifies four conceptualizations of the relation between symptoms and disorders as utilized in diagnostic systems such as the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; American Psychiatric Association, 1994): A constructivist perspective, which holds that disorders are conveniently grouped sets of symptoms; a diagnostic perspective, which holds that disorders are latent classes underlying the symptoms; a dimensional perspective, which holds that symptoms measure latent continua; and a causal systems perspective, which holds that disorders are causal networks consisting of symptoms and direct causal relations between them. Advantages and disadvantages of these conceptualizations are discussed. The author concludes that the psychometric analysis of diagnostic systems is not settled, and that these systems require deeper psychometric analysis than they currently receive.

Familiality of major depressive disorder and gender differences in comorbidity

OBJECTIVE

Gender differences exist in the prevalence and psychiatric comorbidity of major depressive disorder (MDD). This study investigates whether familiality of MDD contributes to observed gender differences in comorbidity.

METHOD

Familial (f-MDD) and non-familial (nf-MDD) MDD cases from a population sample were assessed for comorbid dysthymia, anxiety disorders and alcohol-related disorders using the Composite International Diagnostic Interview (CIDI). Logistic regression analyses were performed to examine the effect of f-MDD on gender differences in comorbidity, adjusted for confounders.

RESULTS

Women with f-MDD reported significantly more comorbid dysthymia and generalized anxiety disorder (GAD) than their male counterparts; women with nf-MDD reported significantly more comorbid simple phobias and agoraphobia than their male counterparts. Gender differences in comorbid panic disorder and alcohol-related disorders occurred independently of the familial load. Adjustment for age of onset, severity and recurrence of MDD did not change these results.

CONCLUSION

Models to explain comorbidity patterns of MDD differ by gender. Familiality of MDD should be taken into account.

Meta-analyses of genetic studies on major depressive disorder

The genetic basis of major depressive disorder (MDD) has been investigated extensively, but the identification of MDD genes has been hampered by conflicting results from underpowered studies. We review all MDD case-control genetic association studies published before June 2007 and perform meta-analyses for polymorphisms that had been investigated in at least three studies. The study selection and data extraction were performed in duplicate by two independent investigators. The 183 papers that met our criteria studied 393 polymorphisms in 102 genes. Twenty-two polymorphisms (6%) were investigated in at least three studies. Seven polymorphisms had been evaluated in previous meta-analyses, 5 of these had new data available. Hence, we performed meta-analyses for 20 polymorphisms in 18 genes. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Statistically significant associations were found for the APOE varepsilon2 (OR, 0.51), GNB3 825T (OR, 1.38), MTHFR 677T (OR, 1.20), SLC6A4 44 bp Ins/Del S (OR, 1.11) alleles and the SLC6A3 40 bpVNTR 9/10 genotype (OR, 2.06). To date, there is statistically significant evidence for six MDD susceptibility genes (APOE, DRD4, GNB3, MTHFR, SLC6A3 and SLC6A4).

Effects of the G(-656)A variant on CREB1 promoter activity in a glial cell line: interactions with gonadal steroids and stress

Major depressive disorder (MDD) constitutes a major public health problem worldwide and affects women twice as frequently as men. Previous genetic studies have revealed significant evidence of linkage of the CREB1 region to mood disorders among women from families with recurrent, early-onset MDD (RE-MDD), a severe and familial subtype of MDD. A rare G to A transition at position -656 in the CREB1 promoter cosegregates with mood disorders in women from these families, implicating CREB1 as a sex-related susceptibility gene for unipolar mood disorders. In the current study, the functional significance of the CREB1 promoter variant was determined using transfection experiments that employed constructs containing the wild-type or variant CREB1 promoters coupled to a reporter gene. The results support the hypothesis that the A(-656) allele contributes to the development of MDD in women by selectively altering the activity of the CREB1 promoter in glial cells exposed to 17 beta-estradiol. Furthermore, the exaggeration of this effect during a simulated stress condition may be relevant to reported gene-environment interactions that contribute to the emergence of MDD in clinical populations. The results of in silico analysis revealed four putative binding sites for transcription factors that are affected by the G to A transition at position -656, of which CP2 best fit the experimental observations.

Linkage scan for quantitative traits identifies new regions of interest for substance dependence in the Collaborative Study on the Genetics of Alcoholism (COGA) sample

Dependence on alcohol and illicit drugs frequently co-occur. Results from a number of twin studies suggest that heritable influences on alcohol dependence and drug dependence may substantially overlap. Using large, genetically informative pedigrees from the Collaborative Study on the Genetics of Alcoholism (COGA), we performed quantitative linkage analyses using a panel of 1717 SNPs. Genome-wide linkage analyses were conducted for quantitative measures of DSM-IV alcohol dependence criteria, cannabis dependence criteria and dependence criteria across any illicit drug (including cannabis) individually and in combination as an average score across alcohol and illicit drug dependence criteria. For alcohol dependence, LOD scores exceeding 2.0 were noted on chromosome 1 (2.0 at 213 cM), 2 (3.4 at 234 cM) and 10 (3.7 at 60 cM). For cannabis dependence, a maximum LOD of 1.9 was noted at 95 cM on chromosome 14. For any illicit drug dependence, LODs of 2.0 and 2.4 were observed on chromosome 10 (116 cM) and 13 (64 cM) respectively. Finally, the combined alcohol and/or drug dependence symptoms yielded LODs >2.0 on chromosome 2 (3.2, 234 cM), 10 (2.4 and 2.6 at 60 cM and 116 cM) and 13 (2.1 at 64 cM). These regions may harbor genes that contribute to the biological basis of alcohol and drug dependence.

Risk for recurrence in depression

Depression is a highly recurrent disorder with significant personal and public health consequences. Prevention of recurrence would be extremely desirable, and thus researchers have begun to identify risk factors that are specific to recurrence, which may be different from risk factors for first onset of depression. Methodological issues in this area of research are briefly reviewed (e.g., the various definitions of "recurrence" and "depression"), followed by a review of studies on specific risk factors, including demographic variables (gender, socio-economic status, and marital status), clinical variables (age at first onset, number of prior episodes, severity of first/index episode, and comorbid psychopathology), family history of psychopathology, and psychosocial and psychological variables (level of psychosocial functioning, cognitions, personality, social support, and stressful life events). In addition, scar theories are evaluated for their potential to explain how these variables and recurrent depression are linked. Our review suggests that recurrent depression reflects an underlying vulnerability that is largely genetic in nature and that may predispose those high in the vulnerability not only to recurrent depressive episodes, but also to the significant psychosocial risk factors that often accompany recurrent depression.

A splice site polymorphism in the G-protein β subunit influences antidepressant efficacy in depression

OBJECTIVE

Recent evidence suggests that signalling cascades located downstream of monoamine receptors are altered following antidepressant treatment. Our objective was to investigate whether genetic polymorphisms in genes involved in these signalling cascades influenced antidepressant efficacy.

METHODS

Polymorphisms in the G-protein beta subunit GNB3, the cAMP response element binding protein 1 gene (CREB1), the brain derived neurotrophic factor (BDNF) and CREB binding protein (CREBBP) were studied in well characterised unipolar (n=166) and early onset (n=102) depressive populations and correlated with treatment response.

RESULTS

The GNB3 C825T polymorphism, which results in a 41 amino acid deletion, was significantly associated with lack of remission (OR=0.18, P=0.02) and lack of response (OR=0.26, P=0.03) following 2nd switch treatment. A cytosine deletion 16 base pairs from the start of exon 8 in CREB1 was found more frequently in remitters and responders to 2nd switch antidepressant drug therapy, although these differences failed to reach significance. Polymorphisms detected BDNF (G196A) and CREBBP (T651 C) did not appear to influence antidepressant response.

CONCLUSIONS

These results suggest that inheritance of the GNB3C825T allele may significantly influence antidepressant response and emphasises the potential importance of polymorphisms in genes in signalling cascades activated by commonly prescribed antidepressants.

Sex differences in the familial transmission of mood disorders

BACKGROUND

Mood disorders exhibit familial transmission due to both environmental and genetic risk factors. Mood disorders are more common in women, yet the role of gender in the familial transmission of mood disorders is unclear. This study examines rates of mood disorder transmission to offspring based on the sex of affected parent, sex of offspring and role of clinical factors, such as childhood abuse history, comorbid psychiatric disorders, and traits of aggression and impulsivity.

METHODS

Risk of transmission of mood disorder to offspring from females and males was compared in a sample of 272 probands with a major mood disorder using generalized estimating equations (GEE). Demographic and clinical characteristics of all male and female probands were compared. Characteristics that differed in probands were entered into the model to obtain an unbiased test of gender differences in transmission rate. Multivariate GEE models, one for male probands and one for female probands, were used to test for risk factors in transmission of mood disorder.

RESULTS

Familial transmission rate of mood disorders from female probands was almost double that of males. There was no difference in transmission to male or female offspring. For male probands, offspring mood disorder was independently associated with earlier age of proband mood disorder onset, greater number of proband years ill, and proband history of childhood abuse. For female probands, offspring mood disorder was associated with higher aggression scores in probands.

LIMITATIONS

We did not directly interview offspring and also had limited data on psychopathology in co-parents. This is a cross-sectional study and cannot account for emergence of illness in offspring in the future.

CONCLUSIONS

The two-fold higher rate of maternal transmission of mood disorder may reflect differences in regulation of maternal and paternal transmission of mood disorder. Future studies need to determine the relative contribution of genetic and non-genetic factors and identify the factors responsible for higher rates of transmission of mood disorders by females with a mood disorder.

Association of a D2S2944 allele with depression specifically among those with substance abuse or antisocial personality

Associations have previously been reported between a 124-bp allele at D2S2944 and recurrent, early-onset depression in women. These earlier reports also noted but did not emphasize a possible association between this allele and alcohol-specific depression. We have analyzed the Iowa Adoption Study data to test this association. D2S2944 allele typing was available for 247 subjects from the Iowa Adoption Studies. Information on lifetime affective, alcohol, drug, and antisocial personality (ASPD) disorders was available from a structured interview. We used logistic regression to analyze adjusted and interactive D2S2944 associations with depression. Controlling other risk factors, the 124-bp allele had a strong association with DSM-IV major depression specific to those with histories of alcohol abuse/dependence and/or ASPD. (Overlap between the two prevented further specification of the interaction.) The association was not gender-specific and was not limited to alcohol-related depressive episodes. This relationship appears stronger than the D2S2944 association previously reported for early-onset depression in women. We note that, in combination with additional liabilities towards depression in women and alcoholism/sociopathy in men, the 124-bp allele may provide a basis for the phenomenon of depressive spectrum illness proposed by Winokur.

Combined linkage and association analyses of the 124-bp allele of marker D2S2944 with anxiety, depression, neuroticism and major depression

A central issue in psychiatric genetics is whether positive findings replicate. Zubenko et al. (2002b, Mol. Psychiatry 7:460-467) reported an association of the 124-bp allele of D2S2944 with recurrent early-onset major depression for females. We tested for association of this allele to continuous measures of anxiety, depression and neuroticism in a Dutch sample of 347 males and 448 females, and to DSM-IV major depression in a subsample of 210 males and 295 females. The association of the 124-bp allele to depression in females was not replicated, but there were significant associations (not significant after correction for multiple testing) with anxiety and anxious depression in males. However, the association occurred in the absence of evidence for linkage in this region on chromosome 2.

Dissecting the genetic etiology of major depressive disorder using linkage analysis

Major depressive disorder (MDD) is clinically and genetically heterogeneous. Studies suggest that recurrence, early onset and comorbid phenotypes define more genetically homogeneous sub-samples. The concordance of linkage findings in recent studies using such approaches is encouraging. Sex-specific analyses and broader phenotypes have also yielded interesting results. These findings indicate that future research should consider comorbid disorders and sex-specific analyses. However, this direction must be approached with caution, owing to the complex multiple-testing issues that arise when considering numerous related phenotypes. With appropriate interpretation, these findings indicate a new potential for positional cloning efforts to locate genes in consensus regions. Genes found might influence specific subtypes of MDD or broader phenotypes, leading to enhanced clinical characterization and management of MDD.

Genome-wide linkage survey for genetic loci that influence the development of depressive disorders in families with recurrent, early-onset, major depression

In this report, we describe the results of the first genome-wide linkage survey for genetic loci that influence the development of unipolar Mood Disorders in 81 families identified by individuals with Recurrent, Early-Onset, Major Depressive Disorder (RE-MDD). Model-free linkage analysis was performed using genotypes for 392 highly informative polymorphisms with an average spacing of 9 cM. The highest maximum LOD score observed, 8.19 (genome-wide adjusted P << 0.0001), occurred for Recurrent Major Depressive Disorder (R-MDD) at D2S2321 (205 cM), located 121 kb proximal to CREB1. Nineteen chromosomal regions contained linkage peaks that reached genome-wide statistical significance (genome-wide adjusted P < 0.05) and ten of these were "highly significant" (adjusted P < 0.001). Six of the 19 linkage peaks were revealed only when the analysis included covariates to control for the effects of sex and linkage to CREB1. Sex-specific susceptibility loci were common and preferentially affected the vulnerability of women to developing unipolar Mood Disorders. Five loci revealed evidence of interaction with the CREB1 locus in determining susceptibility (epistasis). A systematic candidate gene analysis is presented and potential overlaps of the linkage regions for unipolar Mood Disorders with those reported for other psychiatric disorders are discussed. The findings suggest that genes whose products participate in cellular signaling pathways that converge on CREB, as well as the target genes whose expression they regulate, may also harbor alleles that affect the development of Mood Disorders and related conditions.

The association of the D2S2944 124 bp allele with recurrent early onset major depressive disorder in women

Major depressive disorder (MDD) and substance use disorders (SUD) are complex behavioral disorders with 40-50% heritability. Recently, Zubenko and colleagues reported that the 124 bp allele of D2S2944, a tetranucleotide repeat marker on 2q35, is strongly associated with recurrent, early onset MDD (RE-MDD) and alcohol use disorders in women. To test this hypothesis, we examined the association of the 124 bp allele in a subset of 171 adoptees from the Iowa Adoption Studies, a population with high rates of MDD and SUD. We report that in our population, the 124 bp allele significantly associated with RE-MDD in women. There was slight evidence of an increased of SUD in women with the 124 bp allele with the rate of cannabis use disorders reaching statistical significance (P < 0.04) before correction for multiple comparisons. Given the history of prior studies implicating 2q35 as a locus encoding vulnerability to co-morbid alcoholism and depression, these findings strongly suggest that sequence variation conveying increased susceptibility to MDD and possibly SUD is in close proximity to D2S2944.

Sequence variations in CREB1 cosegregate with depressive disorders in women

Major depressive disorder (MDD) constitutes a major public health problem worldwide and affects women twice as frequently as men. Previous linkage studies have identified a 451 kb region of 2q33-35 that exhibited significant evidence of linkage to Mood Disorders among women (but not men) from families with recurrent, early-onset MDD (RE-MDD), a severe and strongly familial subtype of MDD. This 451 kb region includes CREB1, an attractive susceptibility gene for MDD and related disorders. Sequence variations in the CREB1 promoter and intron 8 have been detected that cosegregate with Mood Disorders, or their absence, in women from these families, identifying CREB1 as a sex-limited susceptibility gene for unipolar Mood Disorders. These findings implicate the cAMP signaling pathway in the pathophysiology of Mood Disorders and related conditions.

Genetic linkage of region containing the CREB1 gene to depressive disorders in women from families with recurrent, early-onset, major depression

This report describes the results of a model-free linkage analysis of six polymorphic markers, located in a 15 cM region of chromosome 2q33-35, and unipolar Mood Disorders in 81 families identified by probands with Recurrent, Early-Onset Major Depressive Disorder (RE-MDD), a severe and familial form of clinical depression. Our findings reveal significant evidence of linkage of unipolar Mood Disorders to a 451 Kb region of 2q33-34 flanked by D2S2321 and D2S2208 in these families. Increasing peak LOD scores were observed in both the single point and multipoint analyses for Mood Disorder phenotypes whose definitions embodied progressively less stringent severity criteria for inclusion in the affected group. The sex-dependent multipoint linkage analysis of any Major or Minor Mood Disorders produced LOD scores that reached 6.331 and 6.866 at D2S2321 and D2S2208, respectively. Linkage of Mood Disorders to this region was observed exclusively among female affected relative pairs; no suggestion of linkage was observed when male affected relative pairs were analyzed. These observations imply that a sex-specific susceptibility gene in this region contributes to the vulnerability of women in these families to the development of unipolar Mood Disorders that ranged in severity from minor to severe at the time of clinical assessment. The region between the markers that yielded the peak LOD score includes the CREB1 gene, which encodes a cAMP-responsive element-binding protein (CREB) that is a member of the bZIP family of transcription factors. Based on considerable clinical and preclinical evidence, CREB1 is an attractive candidate for a susceptibility gene for unipolar Mood Disorders. The sex-specificity of the susceptibility locus identified by our study may result from reported synergistic interactions of CREB with nuclear estrogen receptors.

The roots of depression in adolescent girls: is menarche the key?

Before adolescence, the rates of depression are similar in girls and boys (or are slightly higher in boys). Yet with the onset of puberty, the gender proportion of depression dramatically shifts to a two girls to one boy ratio. What, then, is the relationship between menarche and the onset of major depression in early adolescence? Recent literature intimates that vulnerability to depression may be rooted in an intricate meld of genetic traits, normal female hormonal maturational processes, and gender socialization. Information regarding gender differences in the presentation of depressive symptoms is provided along with biologic, psychologic, and sociologic factors contributing to depression in adolescent girls. The burden of illness associated with onset of depression after menarche reinforces the importance of prevention or else expeditious recognition and intervention.