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

Coordinated efforts are now underway to identify susceptibility genes for unipolar major depressive disorder (MDD) and related disorders. These studies have focused on recurrent, early-onset MDD (RE-MDD), thought to be the most familial form of this disorder. The goal of this study was to conduct a complex segregation analysis of recurrent MDD and other major mood disorders aggregating in families identified by probands with RE-MDD. 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 MDD (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. The segregation analysis of recurrent MDD supported a sex-independent Mendelian codominant model. Analysis of major mood disorders supported a sex-independent Mendelian dominant model. Interestingly, inclusion of spousal residual correlations provided better fitting models for recurrent MDD but not the broader phenotype of major mood disorders. Unlike unipolar MDD, the lifetime prevalence of bipolar I disorder in this sample of families did not exceed the reported population prevalence [Zubenko et al., 2001]. Our results suggest that a major locus contributes to the expression of recurrent MDD and possibly other major mood 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). The absence of aggregation of bipolar I disorder in these families strongly suggests that while the genetic determinants of unipolar and bipolar disorders may overlap, they are not identical. Our findings illustrate the advantage of employing families identified by probands with RE-MDD in studies designed to detect susceptibility loci for unipolar MDD and related disorders.     

Family history influences age of onset in bipolar I disorder in females but not in males.

Age of onset (AO) has been proposed as a promising criterion by which to select homogeneous subgroups for the genetic analysis of bipolar disorder. This is the first study to investigate the effect of the interaction between gender and family history (FH)-type on AO in bipolar disorder. In accordance with the literature, no difference in AO was observed between females and males in our sample of 264 Romanian bipolar I probands. Cox regression, however, showed a strong influence of FH-type on AO (P = 0.006). This was due to a significant variation in AO according to the type of FH in females (P = 0.002) but not in males (P = 0.64). Female bipolar disorder patients with a negative FH (FH(-)) had a later AO than females with either a FH of bipolar and/or schizoaffective disorder (P = 0.001) or a FH of recurrent unipolar major depression only (P = 0.04). Females with FH(-) had a later AO than males with FH(-) (P = 0.03). No sex difference was observed for AO in the group with a FH of recurrent unipolar depression. In the group with a FH of bipolar and/or schizoaffective disorder, females had an earlier AO than males (P = 0.01). A trend for support was observed in an independent sample of 217 German bipolar I patients for an influence of FH-type on AO in females (P = 0.09) but not in males (P = 0.15). Female bipolar disorder patients with FH(-) had a later AO than females with either a FH of bipolar and/or schizoaffective disorder (P = 0.04) or a FH of recurrent unipolar major depression only (P = 0.05). Females with FH(-) had a later AO than males with FH(-) (P = 0.05). Other comparisons were statistically not significant, which may be due to limited sample size. Our findings emphasize that the interaction between gender and FH-type is a source of heterogeneity for AO in bipolar disorder.     

Evaluating the parent-of-origin effect in bipolar affective disorder. Is a more penetrant subtype transmitted paternally?

BACKGROUND: Numerous genetic mechanisms and modes of transmission underlying bipolar affective disorder (BPAD) have been postulated. Recently, the discovery of genomic imprinting and mitochondrial transmission of illness in humans has stimulated study of parent-of-origin effects in the transmission of BPAD. METHODS: We examined a large sample of families from an associated linkage study to search for a possible parent-of-origin effect. Selecting for unilineal families with at least one offspring and/or parent diagnosed with BPAD after structured interview, we conducted three analyses: (1) the rates of illness among mothers and fathers of offspring affected with BPAD; (2) the observed frequency of transmission and rates of illness among maternal and paternal lineages; and (3) the rates of affective illness among offspring of parents affected with BPAD. RESULTS: Our results indicate no significant differences in the rates of illness among mothers and fathers of offspring affected with BPAD. Also, the frequency of transmission and rates of illness among maternal and paternal lineages did not differ significantly. However, the rate of BPAD among the offspring of fathers affected with BPAD was significantly higher than for mothers with the illness. LIMITATIONS: Substantially more women than men, and maternal than paternal relatives were studied - introducing possible gender biases. CONCLUSIONS: These results suggest a possible paternal parent-of-origin effect.     

Genetic approach to the study of heterogeneity of affective disorders

In the present paper we compared the results of the application of segregation analysis, under two different single major locus (SML) transmission hypotheses, a dominant one with sex effect and a recessive one, to the families of 202 probands with major depression, recurrent and bipolar disorder. In the first analysis we considered only secondary cases with major affective disorders (bipolar disorders and major depression, recurrent), in the second one we included as affected phenotypes also relatives with atypical depression, dysthymic and cyclothymic disorders. Results indicated that considering spectrum disorders greatly modified familial segregation patterns.     

Close linkage of bipolar disorder to chromosome 11 markers is excluded in two large Australian pedigrees.

The relationship between bipolar disorder and chromosome 11 markers remains uncertain. Whilst re-analysis of the Amish pedigree weakened previous evidence for close linkage (but could not exclude the possibility of genetic heterogeneity), a recent French study has found a significant association between this condition and tyrosine hydroxylase polymorphisms. We aimed to determine if bipolar disorder in two large Australian pedigrees (of Irish and English extraction respectively) was linked to these markers. Of the 84 family members available for testing, nine were diagnosed as bipolar I, one as bipolar II and six had recurrent unipolar depression. Linkage of bipolar disorder and recurrent depression to the chromosome 11p15 markers c-Harvey ras, insulin and tyrosine hydroxylase was tested using a series of genetic models with varying penetrance levels. Additionally, linkage was examined using a series of levels of definitions of affective status (ranging from bipolar I alone to all affective illnesses). Close linkage to these markers was strongly excluded using each model and definition. The findings also persisted when a wide range of rates of 'sporadic' (non-genetic) presentations of illness were incorporated in the analysis. These results are consistent with other recent studies indicating that bipolar disorder is not linked to chromosomal region 11p15.     

Analysis of the tyrosine hydroxylase and dopamine D4 receptor genes in a Croatian sample of bipolar I and unipolar patients

We selected 83 patients with bipolar disorder type I or unipolar recurrent major depression and 71 healthy controls for genetic analysis of the tyrosine hydroxylase and the dopamine D4 receptor gene. No significant association was found between bipolar disorder type I and unipolar recurrent major depression and the polymorphisms located near these genes. Therefore, the hypothesis that the tyrosine hydroxylase and the dopamine D4 receptor genes may be involved in the etiology of bipolar disorder and unipolar recurrent major depression is not supported in our study. Am. J. Med. Genet. 74:176–178, 1997. © 1997 Wiley-Liss, Inc.     

Exclusion of Linkage Between Bipolar Affective Disorder and Chromosome 16 in 12 Australian Pedigrees

Several recent reports of possible susceptibility loci for bipolar affective disorder (BAD) have identified sites on a number of chromosomes. Specifically, two Danish studies have suggested the presence of a susceptibility locus for BAD on chromosome 16p13. As the first step of a whole genome scan, we screened 12 Australian families with markers at 16p13 and also a number of markers spanning the entirety of chromosome 16. Linkage analysis was undertaken using both the parametric lod score method (two- and multipoint) with different models and diagnostic thresholds, and the nonparametric affected pedigree member (APM) method. Results of lod score analysis convincingly excluded the 16p13 region from linkage to BAD in these families, while APM provided no support for linkage. Furthermore, using the broad definition of BAD, with individuals affected by bipolar I and II and recurrent unipolar disorders included, the entire chromosome was excluded from linkage to BAD with autosomal-dominant transmission at a maximum age-specific penetrance of 60%, and with autosomal-dominant and recessive modes of transmission at a maximum age-specific penetrance level of 90%. Diagnostic thresholds which did not include unipolar affected individuals were somewhat less informative. However, a majority (between 63–96%, depending upon the model) of the chromosome was clearly excluded using narrow diagnostic thresholds. Moreover, no positive lod scores were obtained at θ = 0.00 for any tested model or diagnostic threshold. Our results indicate that no linkage exists between BAD and chromosome 16 markers in this group of Australian families. Am. J. Med. Genet. 74:304–310, 1997. © 1997 Wiley-Liss, Inc.     

Impact of comorbid affective and alcohol use disorders on suicidal ideation and attempts.

The effect of concurrent affective and alcohol use disorders on suicidal ideation and behavior was investigated. The Diagnostic Interview Schedule Version III-R (DIS) was administered to 307 adult veteran men ranging in age from 23 to 78. Participants were classified into one of four groups based on their final DIS diagnosis-lifetime unipolar depression and lifetime bipolar I disorder with or without a lifetime alcohol use disorder. Logistic regression analyses indicated that veterans with a major affective disorder were at greater risk for suicidality than veterans without an affective disorder. However, veterans with unipolar depression were at no greater risk for suicidality than those with bipolar I disorder. Unipolar and bipolar I disorders with a concurrent alcohol use disorder were always associated with an increased risk for suicidality.     

Mitochondrial DNA polymorphisms in bipolar disorder

BACKGROUND: Previous studies suggested mitochondrial abnormality in bipolar disorder: (1) possible contribution of parent-of-origin effect in transmission of bipolar disorder; (2) abnormal brain phosphorus metabolism detected by phosphorus-31 magnetic resonance spectroscopy; (3) comorbidity of affective disorders in patients with mitochondrial encephalopathy; (4) increased levels of the 4977bp deletion of mitochondrial DNA (mtDNA) in the postmortem brains. We investigated mtDNA polymorphisms in association with bipolar disorder. METHODS: Twelve PCR fragments including all tRNA genes were examined by the single-strand conformation polymorphism method in 43 bipolar patients. All observed polymorphisms were sequenced. Association of these polymorphisms with bipolar disorder was examined by restriction fragment length polymorphism method in 135 bipolar patients and 187 controls. RESULTS: In total, we found 28 polymorphisms including 14 polymorphisms that have not been reported previously. The A10398G polymorphism was significantly associated with bipolar disorder (10398A genotype: 33.1% in bipolar, 22.2% in the control, P<0.05). Although this difference was not significant after Bonferroni correction, the CA haplotype of the 5178 and 10398 polymorphisms was still significantly associated with bipolar disorder (CA haplotype: 33.6% in bipolar, 16.8% in control, P<0.001). Three rare mutations substituting evolutionary conserved bases; A5539G in tRNA(Trp) gene, A5747G in the origin of L-strand replication, and A8537G in ATPase subunit-6 and -8 genes, were found in patients with family history in which maternal transmission was suspected. DISCUSSION: The 5178C/10398A haplotype in mtDNA may be a risk factor of bipolar disorder (odds ratio, 2.4). Pathophysiological significance of rare mtDNA mutations needs to be verified in the future. This finding may imply the pathophysiological significance of mtDNA in bipolar disorder.     

The Munich Vulnerability Study on Affective Disorders: risk factors for unipolarity versus bipolarity

BACKGROUND: An individual with a high genetic load for psychiatric disorders is subject to a considerable risk factor for an affective illness. Family studies usually try to distinguish between bipolar and unipolar disorders since it was suggested that they might show different modes of inheritance. The aim of this study was to differentiate between healthy members of unipolar and bipolar families without a previous history of any psychiatric disorder according to the neurobiological and psychometric findings. METHODS: We first analysed the results obtained from neurobiological and psychometric measurements taken from 75 healthy subjects who had at least two close relatives with a unipolar and a bipolar disorder. In a second step we examined the subjects with a parental affective disorder; finally, we compared the members of 'pure' unipolar, bipolar and of mixed families to each other. RESULTS: The first-degree relatives of unipolar patients showed a significantly higher REM density and scored higher on scales of 'neuroticism' and 'vegetative lability' than the controls. No significant differences could be noticed between the relatives of unipolar and bipolar patients, either when considering the degree of relationship, or the parental type of affective disorder and the 'purity' of the respective families. CONCLUSIONS: We found some distinct neurobiological and psychometric differences between the relatives of unipolar patients and the control probands. No obvious differences, however, were ascertained between relatives of unipolar and bipolar patients. Therefore, we consider it to be possible that these findings represent potential vulnerability markers for affective disorders in general.     

The relationship between obsessive-compulsive disorder and anxiety and affective disorders: results from the Johns Hopkins OCD Family Study

OBJECTIVE: This study investigates the relationship of specific anxiety and affective disorders to obsessive-compulsive disorder (OCD) in a blind, controlled family study. METHOD: Eighty case and 73 control probands, as well as 343 case and 300 control first-degree relatives of these probands, participated in the study. Subjects were examined by psychologists or psychiatrists using the Schedule for Affective Disorder and Schizophrenia-Lifetime Anxiety version (SADS-LA). Two experienced psychiatrists independently reviewed all clinical materials, and final diagnoses were made according to DSM-IV criteria, by consensus procedure. RESULTS: Except for bipolar disorder, all anxiety and affective disorders investigated were more frequent in case than control probands. Substance dependence disorders were not more frequent. Generalized anxiety disorder (GAD), panic disorder, agoraphobia, separation anxiety disorder (SAD) and recurrent major depression were more common in case than control relatives. These disorders occurred more frequently if the relative was diagnosed with OCD. Only GAD and agoraphobia were more frequent in case relatives independent of OCD. CONCLUSION: GAD and agoraphobia share a common familial aetiology with OCD. The other anxiety and affective disorders, when comorbid with OCD, may emerge as a consequence of the OCD or as a more complex syndrome.     

Anxiety disorders comorbidity in mood disorder subgroups: data from a mood disorders clinic

BACKGROUND: Previous research has identified a high rate of anxiety disorders comorbidity in patients with a primary mood disorder diagnosis. Discrepancies between studies in the comorbidity prevalence of specific anxiety disorders in mood disorders, and of anxiety disorders comorbidity between unipolar depression and bipolar mood disorder are in part due to differences in sampling and diagnostic assessment methodology. METHOD: The authors reviewed the charts of 138 patients who received the SCID-P for DSM-III on enrollment in a Mood Disorders Clinic during the period 1982 through 1988. The comorbidity of specific DSM-III Anxiety Disorders with specific mood disorders was determined and comparatively examined using non-parametric statistics. RESULTS: There was high overall comorbidity of anxiety disorders that did not differ between bipolar and unipolar subjects. There were no differences in the comorbidity of individual anxiety disorder diagnoses in the unipolar vs. bipolar groups. However, in unipolar patients with, compared to those without an additional diagnosis of dysthymia, there was greater overall anxiety disorders comorbidity, with a particularly high prevalence of generalized anxiety disorder. LIMITATION: The subgroup of patients with bipolar I disorder was relatively small (N=8). CONCLUSION: Mood and anxiety disorders comorbidity is complex and presents a continuing challenge for both clinicians and researchers.     

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.     

Family history in recurrent depression

The authors report morbid risks found for depression, alcoholism, and bipolar disorder in first-degree relatives of 179 probands with recurrent depression. Comparisons were made for relatives' gender, probands' gender, and probands' age at onset. Results showed overall morbid risks of 20.7% for non-bipolar depression, 15.4% for alcoholism, and 1.1% for bipolar disorder. Female relatives were found to be at greater risk for depression than males, while the reverse was true for alcoholism. Sex of proband had no effect. Risk to relatives of early-onset probands was significantly elevated compared to late-onset probands. Various cutoffs for ages at onset were examined, and the effect became more marked as the cutoff age was decreased to 20.     

Paternal age effect on age of onset in bipolar I disorder is mediated by sex and family history

This study investigated for the first time in the psychiatric literature the effect of parental age on age-of-onset (AO) in bipolar I disorder (BPI) in relation to proband sex and family history (FH) for major psychoses in a sample of 564 BPI probands. All probands, 72.68% of their first-degree and 12.13% of their second-degree relatives were directly interviewed. The FH-method was used for all unavailable relatives. The diagnoses were made according to DSM-IV(TR) . The impact of parental age on proband early/late AO was evaluated through logistic regression with the cut-off for early AO determined through commingling analysis. We found evidence for a significant influence of increasing paternal age, and especially age ≥ 35 years, on AO of BPI disorder in the total sample (OR = 0.54, CI: 0.35-0.80), in the female subsample (OR = 0.44, CI: 0.25-0.78), in the sporadic subsample (OR = 0.64, CI: 0.38-0.95), and in the subsample with FH of recurrent unipolar major depression (Mdd-RUP) (OR = 0.55, CI: 0.34-0.87). No significant effect of paternal age on disease AO was found in patients with FH of bipolar (BP), schizoaffective disorders (SA), or schizophrenia (SCZ), nor in males. Mean age was significantly higher in fathers of sporadic cases and of cases with FH of Mdd-RUP than in fathers of cases with FH of BP/SA/SCZ (P = 0.011). Maternal age had no significant effect either in the total sample or in subsamples defined by proband sex or FH. In conclusion, in our sample increasing paternal age lowered the onset of BPI selectively, the effect being related to the female sex and FH-type.     

Temperament in the clinical differentiation of depressed bipolar and unipolar major depressive patients

OBJECTIVE: To examine differences in temperament profiles between patients with recurrent unipolar and bipolar depression. METHOD: Depressed individuals with recurrent major depressive disorder (MDD) (n = 94) and those with bipolar (n = 59) disorders (about equally divided between types I and II) were recruited by newspaper advertisement, radio and television announcements, flyers and newsletters, and word of mouth. All patients were interviewed using the Structured Clinical Interview for DSM III-R (SCID) and had the severity of their depressive episode assessed by means of the 17-item Hamilton Rating Scale for Depression. All patients filled out the TEMPS-A, a validated instrument. RESULTS: Temperament differences between bipolar and MDD patients were examined using MANCOVA. Overall significant effect of the fixed factor (bipolar vs. unipolar) was noted for the temperament scores [Hotelling's F((5,142)) = 2.47, p < 0.05]. Overall effects were found for age [F((5,142)) = 2.40, p < 0.05], but not for gender and severity of depression [F((5,142)) = 1.65, p = 0.15 and F((5,142)) = 0.66, p = 0.66, respectively]. Dependent variables included the five subscales of the TEMPS-A, but only the cyclothymic temperament scores showed significant between-group differences. LIMITATION: Small bipolar subsample cell sizes did not permit to test the specificity of the findings for bipolar II vs. bipolar I patients. CONCLUSION: The finding that the clyclothymic subscale is significantly elevated in the bipolar vs. the unipolar depressive group supports the theoretical assumptions upon which the scale is based, and suggests that it might become a useful tool for clinical and research purposes.     

Measuring psychomotor agitation by use of an actimeter: a pilot study

BACKGROUND: Relatives of early-onset bipolar probands have greater risk for affective disorders than those of adult-onset bipolar probands. METHODS: Relatives of 50 adolescent bipolar I probands and 36 adult-onset bipolar probands (onset > or = 25 years) were assessed using the Family Interview for Genetic Studies (FIGS) by a qualified psychiatrist blind to the proband status. Morbid risk was calculated using Weinberg's method of age correction. RESULTS: Relatives of early-onset probands had significantly greater risk for affective disorders compared to the relatives of adult-onset bipolar probands. CONCLUSIONS: Early-onset bipolar disorder is more familial than the adult bipolar disorder. IMPLICATIONS: Subdivision of bipolar disorder according to age-at-onset may identify homogeneous subtypes useful for genetic studies. LIMITATIONS: Patients were recruited from a major psychiatric hospital. The family history method was used to collect information about relatives.     

Minor physical anomalies in affective disorders. A review of the literature

BackgroundThe increased frequency of MPAs may be external markers of abnormal brain development in affective disorders.MethodsA MEDLINE, psychInfo and Web of Science search was evaluated to collect all publications on the prevalence of minor physical anomalies in bipolar affective disorder and unipolar major depression.AimsAs reports on the prevalence of MPAs in affective disorders were controversial, were based on highly different number of patients and were evaluated by the use of scales with different sensitivities, we considered as important to review the current state of knowledge and to recommend directions to further research.Results14 publications on 12 studies were found after a careful literature search. 5 studies have dealt with the prevalence of MPAs in bipolar affective disorder, 3 have reported on examinations among patients with unipolar major depression, while 5 publications on 3 studies combined patients with bipolar affective disorder, schizoaffective disorder and unipolar major depression. 1 study was published on the prevalence of MPAs among mood disorders, without the differentiation of the data of patients with bipolar affective disorder and unipolar major depression.LimitationsFew studies with relatively small size were published, there is no data on the distinction between bipolar I and bipolar II disorders.ConclusionThe reviewed data suggest a higher probability of the role of an aberrant neurodevelopment in bipolar affective disorder and a smaller in unipolar major depression.     

A different depression: clinical distinctions between bipolar and unipolar depression

Delayed diagnosis or misdiagnosis can prolong the suffering of patients with bipolar disorder. Accurate early diagnosis is sometimes difficult, however, particularly because patients often present in the depressive phase, which can easily be mistaken for unipolar depression. Unfortunately, therapy appropriate for unipolar depression can increase the risk of manic switch or cycle acceleration in bipolar disorder, especially in those with a family history of bipolarity and suicide, although some antidepressants may be useful in some bipolar patients. In addition, most currently available mood stabilizers, though effective in managing mania, do not effectively resolve depression. In contrast, lamotrigine has shown activity in bipolar depression and has a very low risk of manic switch. Bipolar depression, compared with unipolar depression, is more likely to be associated with hypersomnia, motor retardation, mood lability, early onset, and a family history of bipolar disorder. Awareness of these distinctions can greatly improve diagnosis of bipolar disorder and provide an opportunity for effective therapeutic intervention.     

Association study of the short tandem repeat in the 5' upstream region of the cholecystokinin gene with mood disorders in the Japanese population

We have recently identified a novel polymorphic short tandem repeat (STR) in the 5' upstream region of the cholecystokinin (CCK) gene and reported its association with panic disorder. A linkage study of affective disorder showed a modest linkage signal on the short arm of chromosome 3, the location of the CCK gene. Furthermore, clinical comorbidity of depression and anxiety disorders have been documented. In the present study, we examined a possible association of the CCK STR with mood disorders. We genotyped 165 subjects with mood disorders consisting of unipolar and bipolar disorders and 253 control samples. However, no significant allelic associations were detected between the STR and either the combined mood disorders (P = 0.885), the unipolar group (P = 0.296), or the bipolar group (P = 0.605). These data suggest that the CCK promoter STR is unlikely to have a major genetic effect on the development of mood disorders in the Japanese population.