Genetic segregation analysis of recurrent, early-onset major depression: evidence for single major locus transmission

Epigenetic and Coping Mechanisms of Stress in Affective Disorders: A Scoping Review

This review aims to explore the intricate relationship among epigenetic mechanisms, stress, and affective disorders, focusing on how early life experiences and coping mechanisms contribute to susceptibility to mood disorders. Epigenetic factors play a crucial role in regulating gene expression without altering the DNA (deoxyribonucleic acid) sequence, and recent research has revealed associations between epigenetic changes and maladaptive responses to stress or psychiatric disorders. A scoping review of 33 studies employing the PRISMA-S (Preferred Reporting Items for Systematic Reviews and Meta-Analyses-Statement) guidelines investigates the role of stress-induced epigenetic mechanisms and coping strategies in affective disorder occurrence, development, and progression. The analysis encompasses various stress factors, including childhood trauma, work-related stress, and dietary deficiencies, alongside epigenetic changes, such as DNA methylation and altered gene expression. Findings indicate that specific stress-related genes frequently exhibit epigenetic changes associated with affective disorders. Moreover, the review examines coping mechanisms in patients with bipolar disorder and major depressive disorder, revealing mixed associations between coping strategies and symptom severity. While active coping is correlated with better outcomes, emotion-focused coping may exacerbate depressive or manic episodes. Overall, this review underscores the complex interplay among genetic predisposition, environmental stressors, coping mechanisms, and affective disorders. Understanding these interactions is essential for developing targeted interventions and personalized treatment strategies for individuals with mood disorders. However, further research is needed to elucidate specific genomic loci involved in affective disorders and the clinical implications of coping strategies in therapeutic settings.

Depression in young adults

Depression, as a heterogeneous collection of disorders, is likely to include subgroups that are more genetic in origin. In common with other neuropsychiatric disorders such as schizophrenia, Alzheimer's disease and Huntington's disease, earlier age at onset in depression is associated with higher genetic loading and poorer long-term outcome. Adolescents and young adults with depression are also at high risk of developing a bipolar illness. This article reviews depressive illnesses that occur for the first time in adolescence and young adulthood. Case studies are used to discuss atypical presentations and the evolving concept of bipolar-spectrum disorders.

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.

Mood and cognition in leucine-rich repeat kinase 2 G2019S Parkinson's disease

The behavioral and cognitive features of the leucine-rich repeat kinase G2019S mutation in Parkinson's disease in the Ashkenazi Jewish population are not well described; therefore, we sought to more systematically characterize these features using a semistructured psychiatric interview and neuropsychological testing. Twenty-one Ashkenazi Jewish patients having the leucine-rich repeat kinase G2019S mutation were compared with age- and sex-matched Ashkenazi Jewish patients with Parkinson's disease without mutations. Although overall rates of affective disorders were not greater in mutation carriers, the carriers exhibited a 6-fold increased risk of premorbid affective disorders (odds ratio, 6.0; P = .10), as determined by the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders-IV. Of interest, we identified 2 leucine-rich repeat kinase carriers with bipolar disorder; no mutation-negative subjects had this diagnosis. Performance on the Hopkins Verbal Learning Test-Revised, Judgment of Line Orientation, and Frontal Assessment Battery was consistent with previous reports and did not differ between groups. Study findings suggest a possible association between premorbid mood disorders and leucine-rich repeat kinase Parkinson's disease, warranting further evaluation.

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.

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.

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.

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.

Family history of mood disorder and characteristics of major depressive disorder: a STAR*D (sequenced treatment alternatives to relieve depression) study

INTRODUCTION

Clinicians routinely ask patients with major depressive disorder (MDD) about their family history. It is unknown, however, if patients who report a positive family history differ from those who do not. This study compared the demographic and clinical features of a large cohort of treatment-seeking outpatients with non-psychotic MDD who reported that they did or did not have at least one first-degree relative who had either MDD or bipolar disorder.

METHODS

Subjects were recruited for the STAR( *)D multicenter trial. Differences in demographic and clinical features for patients with and without a family history of mood disorders were assessed after correcting for age, sex, race, and ethnicity.

RESULTS

Patients with a family history of mood disorder (n=2265; 56.5%) were more frequently women and had an earlier age of onset of depression, as compared to those without such a history (n=1740; 43.5%). No meaningful differences were found in depressive symptoms, severity, recurrence, depressive subtype, or daily function.

CONCLUSIONS

Women were twice as likely as men to report a positive family history of mood disorder, and a positive family history was associated with younger age of onset of MDD in the proband. Consistent with prior research, early age of onset appears to define a familial and, by extension, genetic subtype of major depressive disorder.

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.

High harm avoidance and low self-directedness in euthymic young adults with recurrent, early-onset depression

BACKGROUND

The personality dimensions of harm avoidance (HA) and self-directedness (SD), as measured by the Temperament and Character Inventory (TCI), have been widely associated with depression and there is preliminary evidence that they may represent trait markers for depression. However, many studies in this area are limited by the use of heterogeneous samples of depressed patients and by the confounding effect of depressed mood during personality testing. The current study compares TCI personality dimension scores in a group of euthymic young adults with recurrent early-onset major depressive disorder (RE-MDD) to well-matched euthymic controls.

METHODS

Fifty-two young adults with a past history of RE-MDD were recruited from consecutive referrals to a psychiatric clinic at a university health service. Eighty nine controls were also recruited. Euthymia was established in patients by a score of less than 9 on the Hamilton Rating Scale for Depression (HRSD) and in controls by a Becks Depression Inventory (BDI) score of less than 10. All participants completed the TCI-125.

RESULTS

Patients and controls were well matched in terms of sociodemographic profile. Euthymic RE-MDD patients scored significantly higher than controls on the temperament dimension of harm avoidance (HA; mean score 14.5 versus 7.8, p<0.0001) and significantly lower than controls on the character dimension of self-directedness (SD; mean score 14.1 versus 19.9, p<0.0001). Covariance analysis suggested that both HA and SD contributed independently to the familial risk of depression.

LIMITATIONS

Subjects and controls all came from relatively affluent social backgrounds-these findings may not generalise to more socioeconomically diverse populations. The possibility of a 'scarring effect' of depressive episodes on self-reported personality dimension scores cannot be excluded.

CONCLUSIONS

High HA and low SD represent trait markers for liability to recurrent major depressive disorder in young adults. Further research is needed to replicate these findings and to assess the contribution that the experience of depressive episodes makes to self-reported personality dimension scores.

Genome-wide linkage analyses of extended Utah pedigrees identifies loci that influence recurrent, early-onset major depression and anxiety disorders

Major depressive disorder (MDD) is a common, clinically heterogeneous disorder often found comorbid with other disorders. We studied recurrent, early-onset MDD (MDD-RE) and anxiety disorders in combination to define powerful phenotypes for genetic study. We used 87 large, extended Utah pedigrees to investigate linkage to 3 phenotypes: "MDD-RE;" "MDD-RE or anxiety;" and "MDD-RE and anxiety;" where in the latter definition the disorders must appear comorbid within an individual. Pedigrees ranged in size from 2 to 6 generations and contained 3 to 42 individuals affected with MDD or anxiety (718 total). In primary analyses, we identified three regions with at least suggestive genome-wide evidence for linkage on chromosomes 3centr, 7p, and 18q. Both 7p and 18q are replication findings for related phenotypes. The best linkage evidence was for a novel locus at 3p12.3-q12.3 (LOD = 3.88, "MDD-RE or anxiety") and 18q21.33-q22.2 (LOD = 3.75, "MDD-RE and anxiety"), a well-established susceptibility locus for bipolar disorder. In our secondary sex-specific analyses, we identified two further regions of interest on chromosomes 4q and 15q. Using linked pedigrees, we localized 3centr and 18q to 9.8 and 12.2 cM, respectively, with potential for further localization with the addition of markers in specific pedigrees. Our success in replication and novel locus identification illustrates the utility of large extended pedigrees for common disorders, such as MDD. Further, it supports the hypothesis that MDD and anxiety disorders have over-lapping genetic etiologies and suggests that comorbid diagnoses may be useful in defining more genetically homogeneous forms of MDD for linkage mapping.

JR, Scheftner WA, Weissman MM, Zubenko WN, Boutelle S, Murphy-Eberenz K, MacKinnon D, McInnis MG, Marta DH, Adams P, Knowles JA, Gladis M, Thomas J, Chellis J, Miller E, Levinson DF. Genomewide significant linkage to recurrent, early-onset major depressive disorder on chromosome 15q

A genome scan was performed on the first phase sample of the Genetics of Recurrent Early-Onset Depression (GenRED) project. The sample consisted of 297 informative families containing 415 independent affected sibling pairs (ASPs), or, counting all possible pairs, 685 informative affected relative pairs (555 ASPs and 130 other pair types). Affected cases had recurrent major depressive disorder (MDD) with onset before age 31 years for probands or age 41 years for other affected relatives; the mean age at onset was 18.5 years, and the mean number of depressive episodes was 7.3. The Center for Inherited Disease Research genotyped 389 microsatellite markers (mean spacing of 9.3 cM). The primary linkage analysis considered allele sharing in all possible affected relative pairs with the use of the Z(lr) statistic computed by the ALLEGRO program. A secondary logistic regression analysis considered the effect of the sex of the pair as a covariate. Genomewide significant linkage was observed on chromosome 15q25.3-26.2 (Zlr=4.14, equivalent LOD = 3.73, empirical genomewide P=.023). The linkage was not sex specific. No other suggestive or significant results were observed in the primary analysis. The secondary analysis produced three regions of suggestive linkage, but these results should be interpreted cautiously because they depended primarily on the small subsample of 42 male-male pairs. Chromosome 15q25.3-26.2 deserves further study as a candidate region for susceptibility to 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.

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.

Genetics of recurrent early-onset depression (GenRED): design and preliminary clinical characteristics of a repository sample for genetic linkage studies

This is an initial report on a six-site collaborative project, Genetics of Recurrent Early-Onset Depression (GenRED). This is a study of a large sample of families with recurrent major depressive disorder (DSM-IV) beginning by the age 30 in probands or 40 in relatives. Evidence suggests that early onset and recurrence of depressive episodes predict substantially increased risk of depression in first-degree relatives compared with the general population, suggesting that susceptibility genes might be mapped with this phenotype. The projected sample of 800-1,000 affected sibling pairs (ASPs) and other relatives will be studied using genome scan methods. Biological materials and blinded clinical data will be made available through the NIMH cell repository program. The sample should have good-to-excellent power to detect a locus associated with a 24% or greater population-wide increase in risk to siblings. We describe 838 affected individuals from the first 305 families containing 434 independent ASPs, or 613 ASPs counting all possible pairs. The mean age at the onset was 18.5 years, with a mean of 7.3 episodes and longest episode of 655 days. Almost all subjects had experienced at least 4 weeks of depression with five or more additional symptom criteria. Frequencies of symptoms and psychiatric and medical comorbid are provided. Substance use was more common in males, and panic disorder in females. Within pairs of affected siblings, correlations were significant for age at onset, substance abuse/dependence, panic disorder, obsessive-compulsive disorder and nicotine initiation and persistence. We replicated previously reported associations among comorbid panic disorder and social phobia, chronicity of depression and suicidal behavior. This suggests comparability of our cases to those in earlier large family studies. This dataset should prove useful for genetic studies of a highly familial form of major depressive disorder.

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

Recurrent, early-onset, major depressive disorder (RE-MDD) is a strongly familial condition whose malignant effects have a significant negative impact on the health and longevity of patients and their family members. Sixteen of the 19 candidate susceptibility loci identified by a recent genome survey revealed allelic associations with RE-MDD in men or women, but not in both sexes. The association of D2S2944 alleles and genotypes with RE-MDD and related disorders was evaluated using a case-control study design employing 100 adults with RE-MDD and 100 adult controls who had no personal or family history of mental disorders. The results of the case-control study were subsequently evaluated in a sample of 81 families ascertained through probands with RE-MDD using the transmission/disequilibrium test. The frequency of the D2S2944 124-bp allele among women with RE-MDD was approximately three times that for female controls (P = 0.0003). Women who carried the D2S2944 124-bp allele revealed a significantly elevated risk of developing RE-MDD, as indicated by an odds ratio of 4.5 compared to female controls (P<0.001). In contrast, men with RE-MDD did not have an increased frequency of this allele compared to male controls, and men who were carriers did not exhibit an increased risk of developing RE-MDD or related disorders. Our findings also suggest that the D2S2944 124-bp allele increases the risk of alcohol and other substance use disorders among women with RE-MDD. The transmission/disequilibrium test provided confirmatory evidence of these sex-specific findings within families. The results of this study confirm the existence of sex-specific susceptibility loci for RE-MDD, and suggest that there may be important differences in the molecular pathophysiology of RE-MDD in men and women. Alternatively, our findings may reflect the existence of sex-specific differences in the molecular mechanisms that determine resilience to endogenous or environmental depressogenic stimuli. The identification and characterization of the D2S2944 susceptibility locus for RE-MDD and related substance use disorders is likely to provide important new insights into the clinical biology, treatment, and prevention of these disorders.

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.

Genetic segregation analysis of alcohol and other substance-use disorders in families with recurrent, early-onset major depression

OBJECTIVE

The goal of this study was to conduct a complex segregation analysis of alcohol and other substance-use disorders in families identified by probands with recurrent, early-onset major depression (RE-MDD).

METHOD

Eighty-one families were identified through probands over the age of 18, who met criteria for recurrent (> or = 2 episodes), early-onset (< or = 25 years), nonpsychotic, unipolar major depression (RE-MDD) and included 407 first-degree relatives and 835 extended relatives. Psychiatric diagnoses for probands and their family members who provided blood samples were formulated from structured personal interviews, structured family history assessments, and available medical records. The remaining family members who participated and those who were deceased were evaluated through the family history method augmented by available medical records. Best estimate diagnoses were made during a consensus conference according to established diagnostic criteria. Segregation analyses were performed using the REGD routine in S.A.G.E. release 4.0.

RESULTS

The best-fitting models for the transmission of "alcohol use disorders" or "alcohol/other substance use disorders" were sex-dependent Mendelian recessive models with significant residual spousal effects. Moreover, the parameter estimates for the models were very similar for these phenotypes. In contrast, the segregation analysis of "substance use disorder" supported a transmissible, but non-Mendelian, major effect.

CONCLUSIONS

Our results suggest that a major locus contributes to the expression of alcohol use disorders or alcohol/other substance-use disorders within families identified by probands with RE-MDD. Due to the limitations of the segregation analysis model, our results cannot address whether the same major locus is segregating across families in our sample or whether multiple major loci are involved (genetic heterogeneity). Previous studies supported single gene transmission of recurrent major depression and major mood disorders in these families [Marazita et al. Am. J. Hum. Genet. 1997, 61, 1370-1378; Maher et al. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 2002. 114 (2), 214-221]. Mounting evidence suggests that at.least some of this "comorbidity" may result from the effects of shared susceptibility genes or an overlap in the sets of genes that contribute to the vulnerability of developing these mental disorders [Zubenko, G.S. Mol. Psychiatry 2000, 5, 131-136].

Genome survey for susceptibility loci for recurrent, early-onset major depression: results at 10cM resolution

Recurrent (two or more episodes), early-onset (first episode at < or = 25 years) major depressive disorder (RE-MDD) is a strongly familial condition (lambda(first-degree relatives) = 8) whose malignant effects have a significant negative impact on the health and longevity of patients and their family members. The goal of this study was to identify candidate susceptibility loci that influence the development of RE-MDD. We completed a systematic survey of the human genome, conducted at an average resolution of 10 cM, for the identification of simple sequence tandem repeat polymorphisms (SSTRPs) that target susceptibility genes for RE-MDD by virtue of linkage disequilibrium. The efficiency of our association study was enhanced by genotyping pools of DNA from 100 adults with RE-MDD and 100 adult controls who had no personal or family history of mental disorders. Both groups included equal numbers of Caucasian men and women and were matched as closely as possible for age and ethnicity. Allelic associations with RE-MDD were observed for 19 of the 387 SSTRPs in the CHLC Human Screening Set/Weber Version 9. Sixteen of the 19 candidate susceptibility loci revealed significant allelic associations with RE-MDD in men (n = 7) or women (n = 9), but not in both sexes. Evidence for both risk and protective alleles was detected. Two of the candidate susceptibility loci reside within several Mb of loci previously reported-megabases to be linked to "comorbid alcoholism and depression" in families of individuals with alcoholism and to a broadly defined affected phenotype that included recurrent major depression in the families of patients with bipolar disorder. Although it has been suggested that the genes that influence risk for MDD in the two sexes may not be entirely the same, the results of our study suggest that sex specificity of susceptibility loci for RE-MDD may be the rule rather than the exception. The observed preponderance of sex-specific susceptibility loci for RE-MDD suggests that there may be important differences in the molecular pathophysiology of RE-MDD in men and women. Alternatively, our findings may reflect the existence of sex-specific differences in the molecular mechanisms that determine resilience to endogenous or environmental depressogenic stimuli.