Gerstmann–Sträussler–Scheinker disease with P102L–V129 mutation: a case with psychiatric manifestations at onset

Gerstmann-Sträussler-Scheinker disease (GSS) is an adult onset, rare, genetically determined autosomal dominant prion disease. Clinically, it is characterized predominantly by slowly progressive spino-cerebellar dysfunction with ataxia, absent reflexes in the legs and cognitive impairment. Onset is usually in the fifth decade and in the early phase, ataxia is predominant. Mutations in the prion protein gene (PRNP) had been identified and the most important of these is at codon 129. A genotype-phenotype relationship with genetic polymorphism at residue 129 between methionine and valine has been supposed. We describe a patient with GSS and P102L-V129 mutation in which the onset with prominent psychiatric features characterized by apathy and depression and not with cerebellar sign and the clinical course with seizures, nor observed in P102L-V129 cases, allow us to confirm observations that the GSS caused by the 102 mutation is influenced by the codon 129 polymorphism with a specific genotype-phenotype influence, but probably other additional factors might be considered as background for phenotypic variability.

Lack of association between the 5HT2A receptor polymorphism (T102C) and unipolar affective disorder in a multicentric European study

We report here a case-control association study with T102C polymorphism in the serotonin 2A receptor gene (HTR2A) in patients affected by unipolar affective disorder (UPAD) and in controls. A total of 284 subjects were genotyped (142 UPAD and 142 controls). All subjects were interviewed using standard diagnostic interviews and matched. A homogenous population of unipolar patients with suicidal attempt was identified. Conditional logistic regression was applied. No association of the HTR2A polymorphism was found in the overall sample of 142 UPAD-control pairs regarding allele and genotype frequencies (P=0.36 and P=0.52 respectively) and homo-heterozygote distributions (P=0.91). This study confirms, in a multicentric European sample, the earlier observations that the T102C HTR2A polymorphism is not associated with UPAD. Nevertheless, a type 2 statistical error cannot be excluded. Therefore, to exclude the implication of HTR2A in UPAD, this result must be replicated in larger samples and in other populations using the transmission disequilibrium test and different polymorphisms around HTR2A.

Predicting response to lithium in mood disorders: role of genetic polymorphisms

Lithium is considered to be the first choice mood stabilizer in recurrent mood disorders. Its widespread and large-scale use is the result of its proven efficacy. In spite of this fact, patients have been observed to show a variable response to lithium treatment: in some cases it is completely effective in preventing manic or depressive relapses, while in other cases it appears to show no influence on the disease course. The possible definition of a genetic liability profile for adverse effects and efficacy will be of great help, as lithium therapy needs at least 6 months to be effective in stabilizing mood disorders. During the last few years, a number of groups have reported possible liability genes. Lithium long-term prophylactic efficacy has been associated with serotonin transporter protein, tryptophan hydroxylase and inositol polyphosphate 1-phosphatase variants. A number of other candidate genes and anonymous markers did not yield positive associations. Therefore, even if some positive results have been reported, no unequivocal susceptibility gene for lithium efficacy has been identified. Although the available data may not currently allow a meaningful prediction of lithium response, future research is aimed at the development of individualized treament of mood disorders, including the possibility of 'pharmacological genetic counseling'.

Evidence of association between gamma-aminobutyric acid type A receptor genes located on 5q34 and female patients with mood disorders

Pharmacological evidence suggests the involvement of gamma-aminobutyric acid (GABA) perturbation in the etiology of mood disorders. A linkage study has detected chromosomal area 5q34, where GABA type A (GABA(A)) receptor subunit genes are mapped, as a susceptibility region for mood disorders, making these genes compelling candidates for such diseases. Our prior quantitative trait loci (QTL) analysis of mouse depression models identified a QTL on mouse chromosome 11, a genomic region whose human synteny includes 5q34. This further supports a contribution from GABA(A) receptors to a predisposition towards mood disorder. In the present study, we examined GABA(A) receptor alpha1 (GABRA1), alpha6 (GABRA6) and gamma2 (GABRG2) subunit genes on 5q34. Polymorphisms on GABRA1 and GABRA6 genes displayed significant associations with mood disorders in female patients. These data offer genetic support for a role of GABA(A) receptor genes in susceptibility to mood disorders.

Association study of serotonin transporter gene VNTR polymorphism and mood disorders, onset age and suicide attempts in a Chinese sample

The human serotonin transporter (5-HTT) gene is an important candidate for the pathogenesis of mood disorders. Associations have been reported between a variable-number tandem-repeat polymorphism in intron 2 of the serotonin transporter gene (5-HTTVNTR) and mood disorders in a number of studies of Western and Chinese populations. However, no such relationships have been determined in other analogous research. To replicate these positive findings in a Chinese population and to determine the association between onset age of bipolar disorder and 5-HTTVNTR, we investigated the prevalence of this polymorphism in an independent Chinese population (83 bipolar disorder patients, 77 major depressive disorder patients and 169 controls), demonstrating no significant association between the 5-HTTVNTR polymorphism and mood disorders or age at onset. Further, no association was demonstrated between this polymorphism and suicidal history in mood disorder patients. These negative findings suggest that 5-HTTVNTR does not play a major role in the pathogenesis of mood disorder in Chinese populations.

Sensitivity and specificity of select biological indices in characterizing psychotic patients and their relatives

BACKGROUND

Although studies have detailed biological abnormalities in schizophrenia patients and their first-degree biological relatives, few studies have directly compared the utility of biological indices in these individuals.

METHODS

Measures of global smooth-pursuit ocular motor (OM) function, low frequency and alpha band electroencephalogram (EEG) power, and nonspecific fluctuations (NSF) in electrodermal activity and visibility of the plexus in the nailfold were collected from 136 schizophrenia patients and 67 of their first-degree biological relatives, 71 affective disorder psychotic patients and 68 of their first-degree biological relatives, and 169 nonpsychiatric comparison subjects. We conducted receiver operator characteristic (ROC) analyses to determine how well each index differentiated the patient groups and the groups of first-degree relatives.

RESULTS

Smooth-pursuit ocular motor function, low frequency and alpha band EEG power, and nailfold plexus visibility differentiated schizophrenia patients from nonpsychiatric comparison subjects. Nailfold plexus visibility was the only measure that significantly differentiated schizophrenia patients from both nonpsychiatric controls and affective patients. Smooth-pursuit ocular motor function and the number of electrodermal nonspecific fluctuations differentiated relatives of schizophrenia patients from nonpsychiatric comparison subjects.

CONCLUSION

Increased nailfold plexus visibility may mark a process associated with abnormal brain development leading to schizophrenia. Smooth-pursuit dysfunction may mark genetic vulnerability that is relatively specific to schizophrenia.

Genetic dissection of psychopathological symptoms: insomnia in mood disorders and CLOCK gene polymorphism

We investigated the possible effect of the 3111T/C CLOCK gene polymorphism on sleep disorders in a sample of 620 patients affected by major depressive disorder (MDD) and bipolar disorder (BP). We detected a significantly higher recurrence of initial (P = 0.0001), middle (P = 0.0009), and early (P = 0.0008) insomnia in homozygotes for the C variant and a similar trend concerning decreased need of sleep in BP (P = 0.0074). Other demographic and clinical features were found not related with CLOCK polymorphisms. This preliminary observation leads to hypothesize a possible involvement of the CLOCK gene polymorphism in the sleep disregulations in MDD and BP.

Peripubertal suicide attempts in offspring of suicide attempters with siblings concordant for suicidal behavior

OBJECTIVE

The authors sought to determine 1) whether the risk for familial transmission of suicidal behavior is greater with increased family loading for suicide attempts, and 2) whether the transmission of suicidal behavior is mediated by impulsive aggression.

METHOD

A reanalysis of a high-risk study compared the offspring of three mood disorder proband groups: suicide attempters with a sibling who also attempted suicide (N=19), suicide attempters whose siblings never made a suicide attempt (N=73), and nonsuicidal probands whose siblings also never engaged in suicidal behavior (N=73). Probands and offspring were assessed with respect to psychopathology, suicide attempt history, impulsive aggression, and exposure to familial adversity.

RESULTS

Offspring of suicide attempters with siblings concordant for suicidal behavior showed a higher risk of suicide attempt than did offspring of nonsuicidal probands and had an earlier age at onset of suicidal behavior than offspring of suicide attempters with siblings discordant for suicidal behavior. Probands from sibling pairs concordant for suicidal behavior and their offspring reported greater lifetime impulsive aggression compared with each of the other two proband/offspring groups. In the offspring, impulsive aggression was the most powerful predictor of early age at first suicide attempt.

CONCLUSIONS

Familial loading for suicide attempts may affect rates of transmission as well as age at onset of suicidal behavior, and its effect may be mediated by the familial transmission of impulsive aggression.

Neurodevelopment and mood stabilizers

Mood disorders and schizophrenia share a number of common properties, including: genetic susceptibility; differences in brain structure and drug based therapy. Some genetic loci may even confer susceptibility for bipolar mood disorder and schizophrenia, and some atypical antipsychotic drugs are used as mood stabilizers. As schizophrenia is associated with aberrant neurodevelopment, could this also be true for mood disorders? Such changes could arise pre- or post-natal, however the recent interest in neurogenesis in the adult brain has suggested involvement of these later processes in the origins of mood disorders. Interestingly, the common mood stabilizing drugs, lithium, valproic acid (VPA) and carbamazepine, are teratogens, affecting a number of aspects of animal development. Recent work has shown that lithium and VPA interfere with normal cell development, and all three drugs affect neuronal morphology. The molecular basis for mood stabilizer action in the treatment of mood is unknown, however these studies have suggested both targets and potential mechanisms. Lithium directly inhibits two evolutionarily conserved signal transduction pathways: the protein kinase Glycogen Synthase Kinase-3 (GSK-3) and inositol signaling. VPA can up-regulate gene expression through inhibition of histone deacetylase (HDAC) and indirectly reduce GSK-3 activity. VPA effects are not conserved between cell types, and carbamazepine has no effect on the GSK-3 pathway. All three mood stabilizers suppress inositol signaling, results further supported by studies on the enzyme prolyl oligopeptidase (PO) and the sodium myo-inositol transporter (SMIT). Despite these intriguing observations, it remains unclear whether GSK-3, inositol signaling or both underlie the origins of bipolar disorder.

Genome wide scan using homozygosity mapping and linkage analyses of a single pedigree with affective disorder suggests oligogenic inheritance

The present study reports results from a genome scan on a family with bipolar affective disorder in which the parents are first cousins and four of the offsprings and one grandchild have affective disorder. The study searched for risk loci for affective disorder by searching for homozygous segments or more complex inherited loci using parametric and non-parametric multipoint linkage analysis. In addition dominant, multipoint, affecteds-only linkage analyses were performed as a supplement to previous analyses. On chromosomes 2q31.3, 10, 12q24, and 21q22.3 evidence for a risk locus was obtained by parametric and/or non-parametric linkage analyses and by haplotype sharing. As other studies have found significant or suggestive linkage to bipolar disorder in these chromosome regions this suggests that an oligogenic mode of inheritance is possible in this family involving at least some of the loci. Finally, the work discusses whether homozygosity mapping using parametric and non-parametric linkage analyses may be of value for complex diseases including rare subphenotypes of such disorders.

A systematic review of association studies investigating genes coding for serotonin receptors and the serotonin transporter: I. Affective disorders

The different 5-HT (serotonin) receptors including the serotonin transporter (5-HTT) are candidate genes for affective disorders such as major depressive disorder (MDD) and bipolar disorder (BD). They have been investigated in a number of allelic association studies where the individual results have been inconsistent, and therefore, definite conclusions are difficult to make. Systematic reviews using meta-analytical techniques are a reliable method for objectively and reproducibly assessing individual studies and generating combined result. This study aimed at reviewing published studies investigating the association between affective disorders (MDD and BD) and variation at genes coding for serotonin receptors and the serotonin transporter. We performed National Library of Medicine database searches to identify potential studies. More than 430 articles were reviewed and 86 studies met the inclusion criteria for participation in our review. Of these, 41 studies investigated 45 different 5-HT receptor variants and 45 studies investigated at least one of two commonly studied 5-HTT polymorphisms in MDD. Many studies investigated the association between MDD and BD with the 5-HT2A 102 T/C, the 5-HTT promoter 44 bp insertion/deletion and the intron 2 VNTR polymorphisms, and thus, these could be pooled using meta-analytic techniques. The overall odds ratio (OR) for the combined individual results was significant for BD and the two 5-HTT polymorphisms: Mantel-Haenszel weighted OR=1.14, CI: 1.03-1.26, P=0.015 for the promoter locus (N=3467) and Mantel-Haenszel Weighted odds ratio OR=1.18, CI: 1.05-1.32, P=0.004 for the VNTR locus (N=3620). However, sensitivity analysis indicated that, in each case, the overall positive association could be mostly attributed to the large effect of one individual study. Therefore, these results suggest that, although promising, further studies are required to assess appropriately the evidence suggesting an association between BD and 5-HTT.

Multicentre Italian family-based association study on tyrosine hydroxylase, catechol-O-methyl transferase and Wolfram syndrome 1 polymorphisms in mood disorders

OBJECTIVE

The aim of the present study was to investigate tyrosine hydroxylase, catechol-O-methyl transferase and Wolfram syndrome 1 genes in mood disorders using a family-based association approach.

METHODS

The sample included 134 nuclear mood disorder families, with subjects affected by bipolar disorder (n=103) or major depressive disorder (n=58). All subjects were genotyped using polymerase chain reaction techniques.

RESULTS

No significant transmission disequilibrium was found in the overall sample for any polymorphism. Analysis considering bipolar subjects only, or psychopathology traits as affection status did not influence the observed results.

CONCLUSIONS

The study could not support the involvement of tyrosine hydroxylase, catechol-O-methyl transferase and Wolfram syndrome 1 polymorphisms in mood disorders.

Molecular genetics of affective disorders

Family studies have provided evidence for familial transmission in suicide in major psychiatric disorders, and in particular affective disorders. Even though they may seem contradictory, linkage studies have suggested several genetic regions implicated in affective disorders. Association studies have mainly focused on genes related to serotonergic and monoaminergic pathways. Other genes involved in GABAergic and substance P pathways have also been studied in association studies. Another way to approach the genetics of affective disorders is the definition of more detailed phenotypes. Suicidal behaviour is one of the more largely studied subphenotypes within affective disorders. Tryptophan hydroxylase and serotonin transporter genes, related to the serotonergic pathway, have been found to be associated to suicidal behaviour, in particular violent suicidal behaviour but need to be replicated before definitive conclusion. Improved methodologies and updated tools in genetic studies will improve in the future our knowledge of affective disorders.

Mutational analysis of two positional candidate susceptibility genes for bipolar disorder on chromosome 12q23-q24: phenylalanine hydroxylase and human LIM-homeobox LHX5

OBJECTIVES

In the search for chromosome 12 genes potentially involved in the pathogenesis of bipolar disorder we will screen Phenylalanine hydroxylase and human LIM-homeobox LHX5 genes for sequence variants, both of which have been suggested as candidate genes. The genes lie on chromosome 12q23-24, near the Darier's disease gene, ATP2A2. We have previously reported two families in which the pattern of segregation of illness is consistent with genetic linkage between this chromosomal region and a putative highly penetrant autosomal dominant major affective disorder locus (pedigree 324, maximum LOD=2.1; pedigree 5501, maximum LOD=3.6).

METHODS

We screened the coding and intronic flanking regions of the phenylalanine hydroxylase and LHX5 genes for sequence variation by denaturing high-performance liquid chromatography in individuals from the pedigrees.

RESULTS

In total, nine single nucleotide polymorphisms and one 6 base pair deletion were identified.

CONCLUSION

Our studies allowed us to conclude that none of these variants act as a highly penetrant autosomal dominant susceptibility locus for mood disorder in our families.

Regression methods for assessing familial aggregation of disease

This paper reviews methods for assessing familial aggregation of disease based on simple logistic regression models. Studies are based on a case-control sampling design, where the disease status of the first degree relatives of both cases and controls are obtained. Both 'proband predictive' and 'family predictive' models are discussed, and an example is given using a case-control sample from a lung cancer study in non-smokers. The methods are extended to characterize co-aggregation of two disorders, that is, presence of one disorder in the proband increases the risk of a second disorder in the relative. An example involving eating disorders and depression is given.

Anhedonia in schizophrenia: a distinct familial subtype?

Failures to replicate results in psychiatric genetics might be due to our inability to define the heritable phenotype. Instead of relying entirely on classical nosographical approaches, the use of a candidate symptom approach to identify more homogeneous forms of diseases among affected subjects and subclinical traits among first-degree relatives may increase genetic validity. Anhedonia may be a marker for subjects at risk of schizophrenia or schizophrenia spectrum disorders. We compared the familiality of anhedonia characterized by a high level of physical anhedonia (score above 23) in a sample of schizophrenic probands (N=80) and their relatives (N=78), with that in bipolar patients (N=109), their relatives (N=33) and normal controls (N=94). We identified a subform of schizophrenia characterized by highly anhedonic schizophrenic probands with a three-fold higher familial risk of schizophrenia and schizophrenic spectrum disorders. We also found that their first-degree relatives had a high level of anhedonia. An intrafamilial correlation analysis confirmed the familial nature of anhedonia. Our data suggest that anhedonia is a candidate symptom for schizophrenia. Refining phenotype definition by studying subgroups of anhedonic and non-anhedonic probands with relevant candidate genes might be fruitful.

Association analysis of the insertion/deletion polymorphism in serotonin transporter gene in patients with affective disorder

A polymorphism of serotonin transporter was studied in 226 patients with affective disorders (n = 132 for bipolar, n = 94 for unipolar affective disorder) and in 213 healthy subjects. Consensus diagnosis by at least two psychiatrists, according to the ICD-10 and DSM-IV criteria was made for each patient using SCID (Structured Clinical Interview for DSM-IV Axis I Disorders). A functional polymorphism in the promoter region of serotonin transporter gene, where 44 bp are either inserted (long allele) or deleted (short allele) was analysed. Genotype s/s was significantly more frequent in patients comparing to the control group (P = 0.011 for bipolar and P = 0.003 for unipolar affective disorder)--the most marked association was found in males with bipolar and unipolar illness. The allele frequencies also differ significantly between patients and controls (P = 0.003 for bipolar and P = 0.001 for unipolar affective disorder). The frequency of the low activity (short) allele was higher in patients than in controls (51.1% in bipolar, and 54.3 in unipolar vs 39.4% in controls). We suggest that the presence of allele s may increase the susceptibility to occurrence of affective 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.

Congenitally learned helpless rats show abnormalities in intracellular signaling

BACKGROUND

Affective disorders and the drugs used to treat them lead to changes in intracellular signaling. We used a genetic animal model to investigate to what extent changes in intracellular signal transduction confer a vulnerability to mood or anxiety disorders.

METHODS

Levels of gene expression in a selectively bred strain of rats with a high vulnerability to develop congenitally learned helplessness (cLH), a strain highly resistant to the same behavior (cNLH) and outbred Sprague-Dawley (SD) control animals were compared using quantitative reverse transcription polymerase chain reaction.

RESULTS

Congenitally learned helpless animals had a 24%-30% reduced expression of the cyclic adenosine monophosphate response element binding protein messenger ribonucleic acid (mRNA) in the hippocampus and a 40%-41% increased level of the antiapoptotic protein bcl-2 mRNA in the prefrontal cortex compared to cNLH and SD rats. Other significant changes included changes in the expression levels of the alpha catalytic subunit of protein kinase A, glycogen synthase kinase 3beta, and protein kinase C epsilon.

CONCLUSIONS

Congenitally learned helpless animals show evidence of altered signal transduction and regulation of apoptosis compared to cNLH and SD control animals.

The WFS1 (Wolfram syndrome 1) is not a major susceptibility gene for the development of psychiatric disorders

BACKGROUND

Wolfram syndrome is a neurodegenerative disorder that is inherited in an autosomal recessive mode and characterized by the presence of diabetes mellitus and optic atrophy. Patients and heterozygote carriers are at an increased risk of suffering psychiatric disorders. Mutations in the Wolfram gene (WFS1 ) (4p16.1) are responsible for the development of the disease, and mRNA and protein expression of WFS1 have recently been found in areas of the rat brain that can be related to the psychiatric symptoms.

OBJECTIVE

To test the hypothesis that WFS1 mutations in heterozygote carriers or other variants of WFS1 can predispose to mental illness.

METHODS

Stage 1: Exons 2, 4 and 8 of that harbour mutations in Spanish Wolfram syndrome families were examined by Single Strand Conformation Polymorphism and sequencing analysis in 43 patients with affective disorder to identify variants and mutations. Stage 2: two variants identified in stage 1 were analysed in 152 psychiatric patients (118 schizophrenia and 34 affective disorder) and 177 control subjects.

RESULTS

Six variants (I333V Ile-->Val, F341, N500, R708, K774, K811) and a WFS1 mutation (R818C, Arg-->Cys) were found in the 43 patients analysed in stage 1 of the study. In stage 2, the R818C mutation was not found in the group of psychiatric patients but it was present in one control subject. The association study conducted with the I333V variant did not find significant differences in allele or genotype frequencies between patients and control subjects.

CONCLUSIONS

Our results suggest that WFS1 is not a major susceptibility gene for the development of psychiatric disorders in our population.

Stressful life events and affective illness

OBJECTIVE

To investigate the association between the occurrence of affective illnesses and the number/type of experienced negative stressful life events in a twin material. A case-control study with an unrelated twin as control to the case and a co-twin control study were both undertaken with the same material.

METHOD

Postal questionnaire responses were used for confirming diagnosis and to inventory stressful life events. Risk ratios (RR) for groups of events were calculated using conditional logistic regression.

RESULTS

A dose-response relationship was observed for the association between stressful life events and affective illness. The RRs for specific groups of exposures were higher in the co-twin control study and higher for dizygotic twin pairs than for monozygotic twin pairs.

CONCLUSION

Individuals with a history of affective illness select themselves into high-risk environments, in part due to their genetic propensity to the disease. Thus, the association represents a classic genotype-environment correlation.

Psychological complexity: barriers to its integration into the neurobiology of major psychiatric disorders

In the authors' experience interactions between clinical and laboratory research have been greatly mutually facilitatory in the understanding and development of new treatments for the major mental illnesses. Examples in the literature are also highlighted to show how cross-disciplinary studies are important in understanding the subtle interactions of genetic and environmental mechanisms in psychiatric illness. Yet, the results of some current science policies encouraging project focus and superspecialization can lead to the separation of clinical and basic investigators, which threatens the integration of psychological complexity into the neurobiology of psychiatry at both a molecular and behavioral level. This paper endorses renewed effort toward the multidisciplinary team approach under the leadership of a physician-scientist in order to better integrate many fields of study critical to ameliorating the effects of psychiatric illness.

Family study of affective spectrum disorder

BACKGROUND

Affective spectrum disorder (ASD) represents a group of psychiatric and medical conditions, each known to respond to several chemical families of antidepressant medications and hence possibly linked by common heritable abnormalities. Forms of ASD include major depressive disorder (MDD), attention-deficit/hyperactivity disorder, bulimia nervosa, cataplexy, dysthymic disorder, fibromyalgia, generalized anxiety disorder, irritable bowel syndrome, migraine, obsessive-compulsive disorder, panic disorder, posttraumatic stress disorder, premenstrual dysphoric disorder, and social phobia. Two predictions of the ASD hypothesis were tested: that ASD, taken as a single entity, would aggregate in families and that MDD would coaggregate with other forms of ASD in families.

METHODS

Probands with and without MDD, together with their first-degree relatives, were interviewed using the Structured Clinical Interview for DSM-IV and a supplemental interview for other forms of ASD. The familial aggregation and coaggregation of disorders were analyzed using proband predictive logistic regression models, including a novel bivariate model for the presence or absence of each of 2 disorders in a relative as predicted by the presence or absence of each of 2 disorders in the associated proband.

RESULTS

In the 178 interviewed relatives of 64 probands with MDD and 152 relatives of 58 probands without MDD, the estimated odds ratio (95% confidence interval) for the familial aggregation of ASD as a whole was 2.5 (1.4-4.3; P =.001) and for the familial coaggregation of MDD with at least one other form of ASD was 1.9 (1.1-3.2; P =.02).

CONCLUSIONS

Affective spectrum disorder aggregates strongly in families, and MDD displays a significant familial coaggregation with other forms of ASD, taken collectively. These results suggest that forms of ASD may share heritable pathophysiologic features.