Association study of the adrenergic receptors and childhood-onset mood disorders in Hungarian families

The adrenergic system has been implicated in the etiology of depression based on a number of lines of evidence, particularly, the mechanism of some classes of antidepressants which increase the synaptic levels of norepinephrine. Further, several genome scans for mood disorders, both unipolar and bipolar, have indicated linkage to the chromosomal regions of 5q23-q33.3, 8p12-p11.2, 4p16, and 10q24-q26, the location of the adrenergic receptors alpha1B (ADRA1B), beta3 (ADRB3), alpha2C (ADRA2C), alpha2A (ADRA2A), and beta1 (ADRB1). In this manuscript, we report on the relationship of the adrenergic receptors and depression using a family based association approach and 189 families (223 affected children) with childhood-onset mood disorder (COMD) collected in Hungary. We found no significant evidence for an association with any of the 24 markers, in total, tested across these genes using single marker analysis or haplotypes of markers across these genes. The results in the present sample indicate that these nine genes are unlikely to be major susceptibility genes contributing to COMD.

The serotonin-1Dbeta receptor gene and severity of obsessive-compulsive disorder in women with bulimia nervosa

BACKGROUND

There is significant evidence that eating disorders have an important biological overlap with obsessive-compulsive disorder (OCD), though the specific mediators of this relationship remain unclear. Recent evidence suggests that the G861C polymorphism of the 5HT-1Dbeta receptor gene and the G allele in particular may play a role in OCD. We thus hypothesized that, among a heterogenous group of probands with bulimia nervosa (BN), this same G allele might predict the presence and/or severity of OCD pathology.

METHODS

165 consecutive female probands with BN were genotyped for the G861C polymorphism of the 5HT-1Dbeta receptor gene. Rates of full syndrome OCD, partial syndrome OCD and no OCD were compared across the three genotypic groups defined by this polymorphism.

RESULTS

45 out of 165 BN probands (27.3%) had either full or partial syndrome OCD. In the full sample, there was a significant difference in the distribution of the three diagnostic groups by genotype (chi2=10.07, df=4, p=.039). The G861C polymorphism did not strongly predict which probands had any vs. no OCD pathology. However, among the 45 probands with OCD symptoms, the G861C polymorphism did strongly differentiate full syndrome vs. partial syndrome OCD (chi2=9.26, df=2, p=.01; odds ratio for full syndrome OCD with GG genotype=7.69, 95% CI=1.45-40.9).

DISCUSSION

In women with BN, the G861C polymorphism of the 5HT-1Dbeta gene does not appear to be associated with the generation of OCD symptoms; however, it might directly or indirectly be associated with a modulatory effect on syndrome severity in probands otherwise predisposed to OCD. While preliminary and in need of replication in other samples, this is the first association study to suggest how a particular gene might influence OCD pathology in an eating disorder population.

Association of the calcyon gene (DRD1IP) with attention deficit/hyperactivity disorder

Attention deficit/hyperactivity disorder (ADHD) is a childhood-onset disorder characterized by marked inattention, hyperactivity and impulsivity. The dopaminergic system has been hypothesized to be involved in the development of ADHD. Positive associations have been found for the dopamine receptors D1 and D5 genes, suggesting that other genes involved in D1/D5 signalling may also contribute to ADHD. In this study, we tested the calcyon gene (DRD1IP), which encodes a brain-specific D1-interacting protein involved in D1/D5 receptors calcium signalling, for association with ADHD. The inheritance of nine polymorphisms in the calcyon gene was examined in a sample of 215 nuclear families, with 260 affected children, using the transmission/disequilibrium test. The most common haplotype, designated C1, demonstrated significant evidence for excess transmission. Quantitative trait analyses of this haplotype showed significant relationships with both the inattentive (parent's rating, P=0.006; teacher's rating, P=0.003) and hyperactive/impulsive (parent's rating, P=0.004) dimensions of the disorder. Two of the nine marker alleles included in haplotype C1, rs4838721A located approximately 10 kb 5' of the gene and rs2275723C located 10 bp upstream of the exon 5 acceptor splice site, also showed significant evidence for association when analysed individually. As these two variants are not predicted to alter calcyon function, we screened the gene exons by sequencing. No variation in the coding region was identified, suggesting that a causal variant allele resides elsewhere in a regulatory sequence of the gene. These findings support the proposed involvement of the calcyon gene in ADHD and implicate haplotype C1 as containing a risk allele.

The SNAP25 gene as a susceptibility gene contributing to attention-deficit hyperactivity disorder

The synaptosomal-associated protein of 25 kDa gene (SNAP25) has been suggested as a genetic susceptibility factor in attention-deficit hyperactivity disorder (ADHD) based on the mouse strain coloboma. This strain is hemizygous for the SNAP25 gene and displays hyperactivity that responds to dextroamphetamine, but not to methylphenidate. Previously, we reported association of SNAP25 and ADHD using two polymorphisms. To further investigate this gene, we screened the exons for DNA variation and genotyped ten additional polymorphisms in an expanded sample of families from Toronto and a second sample of families collected in Irvine, CA. Significant results were observed in the Toronto sample for four markers, although not in the Irvine sample. The paper discusses the possible influence of the selection criteria on these differential results. The Irvine sample selected subjects that met the DSM-IV combined subtype diagnosis, whereas the Toronto sample included all subtypes. Analysis of the DSM-IV subtypes in the Toronto sample indicated that the differential results were not attributable to ADHD subtype. Differences in ethnicity, differential medication response, and other clinical characteristics of the samples cannot be ruled out at this time. Quantitative analysis of the dimensions of hyperactivity/impulsivity and inattention in the Toronto sample found that both behavioral traits were associated with SNAP25. Our findings continue to support SNAP25 in the susceptibility to ADHD.

Lack of association between polymorphism of the human cyclic GMP-dependent protein kinase gene and obesity

OBJECTIVE

To investigate whether genetic variation in the cyclic GMP-dependent protein kinase gene (PRKG1) is associated with obesity.

METHODS

The study included 143 individuals from New York City area, NY, USA. The subjects were sampled on the basis of body mass index (BMI): obese (BMI ranging from 33.8 to 89.5 kg/m(2)), and nonobese (BMI ranging from 16.0 to 29.4 kg/m(2)). The association between C2276T polymorphism in PRKG1 gene and obesity was tested using linear regression analysis.

RESULTS

BMI levels were predicted by linear regression models adjusted for demographic factors. An analysis was performed twice: in individuals of all ethnic backgrounds and in European-Americans only. In both cases, genotype did not have a significant effect.

CONCLUSION

We found no evidence that the C2276T polymorphism in the PKRG1 gene is associated with obesity.

Untranslated region haplotype in dysbindin gene: analysis in schizophrenia

Genome-scans performed in schizophrenia families have provided evidence for region 6p24-21 where variability may confer susceptibility to schizophrenia. Recent studies have implicated that gene DTNBP1 (dysbindin) in this region is strongly associated with schizophrenia. In a family based association study we investigated three markers located in the untranslated region of the DTNBP1 gene: rs909706, rs1047631 and rs742106. The sample size of our study is 117 families. No biased transmission towards the disorder was detected by haplotype analysis using TRANSMIT.

Brain-derived neurotrophic factor variants are associated with childhood-onset mood disorder: confirmation in a Hungarian sample

Brain-derived neurotrophic factor (BDNF) is a nerve growth factor that has been implicated in the neurobiology of depression. Our group has previously reported an association between a BDNF variant and childhood-onset mood disorder (COMD) in an adult sample from Pittsburgh. We hypothesize that variants at the BDNF locus are associated with COMD. Six BDNF polymorphisms were genotyped in 258 trios having juvenile probands with childhood-onset DSM-IV major depressive or dysthymic disorder. BDNF markers included the (GT)n microsatellite, Val66Met and four other single-nucleotide polymorphisms (SNPs) distributed across the BDNF gene. Family-based association and evolutionary haplotype analysis methods were used. Analysis of linkage disequilibrium (LD) revealed substantial LD among all six polymorphisms. Analyses of the Val66Met polymorphism demonstrated significant overtransmission of the val allele (chi2=7.12, d.f.=1, P=0.0076). Consistent with the pattern of LD, all other SNPs showed significant biased transmission. The (GT)n microsatellite alleles also indicated a trend towards biased transmission (170 bp: Z=2.095, P=0.036). Significant haplotypes involved Val66Met and BDNF2 (P=0.0029). In this Hungarian sample, we found all five BDNF SNPs tested and a haplotype containing the BDNF Val66Met Val allele to be associated with COMD. These results provide evidence that BDNF variants affect liability to juvenile-onset mood disorders, supported by data from two independent samples.

Association study of CREB1 and childhood-onset mood disorders

Several lines of evidence suggest that the cellular pathways involved in synaptic plasticity contribute to the risk of depression. These findings include the evidence that chronic antidepressant treatment upregulates the cAMP signal transduction cascade resulting in increased expression and function of the cAMP responsive element binding protein (CREB), a transcription factor that increases the expression of key growth factors involved in synaptogenesis and neurogenesis. Recently, linkage to CREB1 was reported for early-onset depression in families recruited from the Pittsburgh area. This finding was significant only in female sibling pairs from those families. Two specific DNA variants, -656G/A and a C insertion/deletion in intron 8, were identified in CREB1 that co-segregated with depression in two of the families. We sought to investigate the relationship of CREB1 to childhood-onset mood disorders (COMD) using a sample of 195 nuclear families (225 affected children) collected in Hungary. We genotyped the two CREB1 DNA variants previously identified as linked to depression as well as three additional polymorphisms spanning the gene. In addition, we genotyped the -656G/A DNA change and the intron 8 polymorphism in a sample of 112 probands with mood disorders collected in the Pittsburgh area and matched controls, and examined the distribution of alleles. The -656A allele was not observed in our samples and there was no evidence for association of the intron 8 polymorphism in either the sample from Pittsburgh (chi(2) = 0.061, 1 d.f., P = 0.803) or Hungary (chi(2) = 0.040, 1 d.f., P = 0.842). We found no evidence for an association with the other three polymorphisms or with the haplotypes of these markers. Further, we found no sex-specific relationship. Our results, therefore, do not support the previous evidence for this gene as a major factor contributing to depression.

Genetic study of the myelin oligodendrocyte glycoprotein (MOG) gene in schizophrenia

Schizophrenia (SCZ) is a neuropsychiatric disorder that affects approximately 1% of the general population. The human leukocyte antigen (HLA) system has been implicated in several genetic studies of SCZ. The myelin oligodendrocyte glycoprotein (MOG) gene, which is located close to the HLA region, is considered a candidate for SCZ due to its association with white matter abnormalities and its importance in mediating the complement cascade. Four polymorphisms in the MOG gene (CA)n (TAAA)n, and two intronic polymorphisms, C1334T and C10991T, were investigated for the possibility of association with SCZ using 111 SCZ proband and their families. We examined the transmission of the alleles of each of these polymorphisms with the transmission disequilibrium test. We did not observe significant evidence for biased transmission of alleles at the (CA)n (chi2=2.430, 6 df, P=0.876) (TAAA)n (chi2=3.550, 5 df, P=0.616), C1334T (chi2=0.040, 1 df, P=0.841) and C10991T (chi2=0.154, 1 df, P=0.695) polymorphisms. Overall haplotype analysis using the TRANSMIT program was also not significant (chi2=7.954, 9 df, P=0.539). Furthermore, our results comparing mean age at onset in the genotype groups using the Kruskal-Wallis Test were not significant. Our case-control analyses (182 cases age-, sex- and ethnicity-matched with healthy controls) and combined z-score [(CA)n: z-score=-1.126, P=0.130; (TAAA)n: z-score=-0.233, P=0.408; C1334T: z-score=0.703, P=0.241; C10991T: z-score=0.551, P=0.291] were also not significant. Although our data are negative, the intriguing hypothesis for MOG in SCZ may warrant further investigation of this gene.

Association study of brain-derived neurotrophic factor in adults with a history of childhood onset mood disorder

Brain-derived neurotrophic factor (BDNF) is a nerve growth factor that has antidepressant-like effects in animals. BDNF gene polymorphisms have been associated with bipolar disorder. We tested two genetic polymorphisms of BDNF for their association with childhood-onset mood disorders (COMD) within the context of a case-control design. Two BDNF polymorphisms, a dinucleotide repeat (GT)(n), and a single nucleotide polymorphism (SNP) in the coding region, val66met, were genotyped in 99 adults with a history of COMD and matched psychiatrically healthy controls. A genomic control (GC) method was used to evaluate population substructure. Alleles at (GT)(n) were highly associated with COMD in this sample (chi(2) = 17.8; d.f. = 5; P = 0.0032). The odds of carrying the 168 bp allele were 3.94 times greater for cases than controls (CI = 1.72-9.04). Alleles of val66met were not significantly associated with COMD. GC analysis suggested population substructure was not a confounder of association. Analysis of haplotypes, in which (GT)(n) was treated as a binary variable (long vs. short alleles), provided significant evidence that the haplotype val/short contributes to liability to COMD. The BDNF (GT)(n) marker and the val/short haplotype are associated with COMD in this sample, in accordance with the previously described neurotrophic hypothesis of depression and some previous studies of association for bipolar disorder and neuroticism.

Association study of serotonin-2A receptor gene polymorphism and panic disorder in patients from Canada and Germany

The T102C serotonin-2A (5-HT2A) receptor gene polymorphism has been studied extensively in a number of complex psychiatric conditions with mixed results. Recently a genetic association has been described between this polymorphism and panic disorder in a Japanese sample. To evaluate the impact of the T102C polymorphism in panic disorder we genotyped triad families (panic disorder patient and parents), and cases with controls in Canadian and German samples. No significant transmission disequilibrium was observed between the alleles of the T102C 5-HT2A receptor gene polymorphism and panic disorder, nor was a significant excess of either allele found in the case control analysis. Our data suggest thus that this polymorphism is unlikely to play a major role in the pathogenesis of panic disorder.

Genome-wide scan in Portuguese Island families implicates multiple loci in bipolar disorder: fine mapping adds support on chromosomes 6 and 11

As part of an extensive study in the Portuguese Island population of families with multiple patients suffering from bipolar disorder and schizophrenia, we performed an initial genome-wide scan of 16 extended families with bipolar disorder that identified three regions on chromosomes 2, 11, and 19 with genome-wide suggestive linkage and several other regions, including chromosome 6q, also approached suggestive levels of significance. Dick et al. [2003: Am J Hum Genet 73:107-114] recently reported in a study of 250 families with bipolar disorder a maxLOD score of 3.61 near marker D6S1021 on chromosome 6q. This study replicates this finding having detected a peak NPL = 2.02 (P = 0.025) with the same marker D6S1021(104.7 Mb). Higher-density mapping provided additional support for loci on chromosome 6 including marker D6S1021 with an NPL = 2.59 (P = 0.0068) and peaking at marker D6S1639 (125 Mb) with an NPL = 3.06 (P = 0.0019). A similar pattern was detected with higher-density mapping of chromosome 11 with an NPL = 3.15 (P = 0.0014) at marker D11S1883 (63.1 Mb). Simulations at the density of our fine mapping data indicate that less than 1 scan out of 10 would find two such scores genome-wide in the same scan by chance. Our findings provide additional support for a susceptibility locus for bipolar disorder on 6q, as well as, suggesting the importance of denser scans. Published 2004 Wiley-Liss, Inc.

Glutamate receptor, ionotropic, N-methyl D-aspartate 2A (GRIN2A) gene as a positional candidate for attention-deficit/hyperactivity disorder in the 16p13 region

The glutamate system may be involved in the development of attention-deficit/hyperactivity disorder (ADHD) based on animal models and the role of N-methyl-D-aspartate receptors (NMDAR) in cognition and motor processes. A follow-up study of the first genome scan for ADHD identified significant evidence for linkage to the 16p13 region. The glutamate receptor, ionotropic, N-methyl D-aspartate 2A (GRIN2A) gene that encodes the 2A subunit of the NMDA receptor, resides in this region and a recent study has reported an association between this gene and ADHD. We tested for linkage between the alleles and haplotypes of four polymorphisms at the GRIN2A locus and ADHD in our sample of 183 nuclear families with 229 affected children. In contrast to previous findings, we did not identify any evidence for a relationship of these markers and ADHD. Owing to the role of GRIN2A in aspects of cognition, we investigated the relationship of this gene to the cognitive phenotypes of inhibitory control, verbal short-term memory and verbal working memory. There was no significant evidence of linkage between GRIN2A and these phenotypes. While the results were not significant in our sample, the previous association finding suggests that further study of this gene is warranted.

Linkage of the dopamine receptor D1 gene to attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) has a strong genetic basis, and evidence from human and animal studies suggests the dopamine receptor D1 gene, DRD1, to be a good candidate for involvement. Here, we tested for linkage of DRD1 to ADHD by examining the inheritance of four biallelic DRD1 polymorphisms [D1P.5 (-1251HaeIII), D1P.6 (-800HaeIII), D1.1 (-48DdeI) and D1.7 (+1403Bsp1286I)] in a sample of 156 ADHD families. Owing to linkage disequilibrium between alleles at the four markers, only three haplotypes are common in our sample. Using the transmission/disequilibrium test (TDT), we observed a strong bias for transmission of Haplotype 3 (1.1.1.2) from heterozygous parents to their affected children (P=0.008). Furthermore, using quantitative trait TDT analyses, we found significant and positive relationships between Haplotype 3 transmission and the inattentive symptoms, but not the hyperactive/impulsive symptoms, of ADHD. These findings support the proposed involvement of DRD1 in ADHD, and implicate Haplotype 3, in particular, as containing a potential risk factor for the inattentive symptom dimension of the disorder. Since none of the four marker alleles comprising Haplotype 3 is predicted to alter DRD1 function, we hypothesize that a functional DRD1 variant, conferring susceptibility to ADHD, is on this haplotype. To search for such a variant we screened the DRD1 coding region, by sequencing, focusing on the children who showed preferential transmission of Haplotype 3. DNA from 41 children was analysed, and no sequence variations were identified, indicating that the putative DRD1 risk variant for ADHD resides outside of the coding region of the gene.

Genomewide linkage analysis of bipolar disorder by use of a high-density single-nucleotide-polymorphism (SNP) genotyping assay: a comparison with microsatellite marker assays and finding of significant linkage to chromosome 6q22

We performed a linkage analysis on 25 extended multiplex Portuguese families segregating for bipolar disorder, by use of a high-density single-nucleotide-polymorphism (SNP) genotyping assay, the GeneChip Human Mapping 10K Array (HMA10K). Of these families, 12 were used for a direct comparison of the HMA10K with the traditional 10-cM microsatellite marker set and the more dense 4-cM marker set. This comparative analysis indicated the presence of significant linkage peaks in the SNP assay in chromosomal regions characterized by poor coverage and low information content on the microsatellite assays. The HMA10K provided consistently high information and enhanced coverage throughout these regions. Across the entire genome, the HMA10K had an average information content of 0.842 with 0.21-Mb intermarker spacing. In the 12-family set, the HMA10K-based analysis detected two chromosomal regions with genomewide significant linkage on chromosomes 6q22 and 11p11; both regions had failed to meet this strict threshold with the microsatellite assays. The full 25-family collection further strengthened the findings on chromosome 6q22, achieving genomewide significance with a maximum nonparametric linkage (NPL) score of 4.20 and a maximum LOD score of 3.56 at position 125.8 Mb. In addition to this highly significant finding, several other regions of suggestive linkage have also been identified in the 25-family data set, including two regions on chromosome 2 (57 Mb, NPL = 2.98; 145 Mb, NPL = 3.09), as well as regions on chromosomes 4 (91 Mb, NPL = 2.97), 16 (20 Mb, NPL = 2.89), and 20 (60 Mb, NPL = 2.99). We conclude that at least some of the linkage peaks we have identified may have been largely undetected in previous whole-genome scans for bipolar disorder because of insufficient coverage or information content, particularly on chromosomes 6q22 and 11p11.

PedSplit: pedigree management for stratified analysis

SUMMARY

PedSplit facilitates pedigree management for gene-gene interaction and sex specific tests for increased homogeneity within subgroups. PedSplit also provides a simple approach for calculating haplotype relative risk and generating internal 'controls'.

AVAILABILITY

Executables, C++ source code and documentation for PedSplit can be downloaded from http://www.pharmacogenetics.ca in the links and software section.

Genome-wide scan in Portuguese Island families identifies 5q31-5q35 as a susceptibility locus for schizophrenia and psychosis

Schizophrenia is a common psychiatric disorder with a complex genetic etiology. To understand the genetic basis of this syndrome in Portuguese Island populations, we performed a genome-wide scan of 29 families with schizophrenia, which identified a single region on 5q31-5q35 with strong linkage (NPL=3.09, P=0.0012 at D5S820). Empirical simulations set a genome-wide threshold of NPL=3.10 for significant linkage. Additional support for this locus in schizophrenia comes from higher-density mapping and mapping of 11 additional families. The combined set of 40 families had a peak NPL=3.28 (P=0.00066) at markers D5S2112-D5S820. These data and previous linkage findings from other investigators provide strong and consistent evidence for this genomic region as a susceptibility locus for schizophrenia. Exploratory analyses of a novel phenotype, psychosis, in families with schizophrenia and bipolar disorder detected evidence for linkage to the same markers as found in schizophrenia (peak NPL=3.03, P=0.0012 at D5S820), suggesting that this locus may be responsible for the psychotic symptoms observed in both diseases. Molecular Psychiatry (2004) 9, 213-218. doi:10.1038/sj.mp.4001418 Published online 30 December 2003

Childhood inattention and dysphoria and adult obesity associated with the dopamine D4 receptor gene in overeating women with seasonal affective disorder

There is significant evidence that altered dopamine activity plays a role in seasonal affective disorder (SAD). The current study examined three separate genetic hypotheses for SAD related to the 7-repeat allele (7R) of the dopamine-4 receptor gene (DRD4), a variant associated with decreased affinity for dopamine. We examined the possible contribution of 7R to the overall expression of SAD, attention deficit disorder (ADD) comorbidity, and body weight regulation. As part of an ongoing genetic study of increased eating behavior and mood in female subjects, 108 women with winter SAD and carbohydrate craving/weight gain were administered the Wender-Utah Rating Scale to measure childhood ADD symptomatology, and a questionnaire to assess maximal lifetime body mass index (BMI). To test for an association between 7R and the categorical diagnosis of SAD, the transmission disequilibrium test (TDT) was used in a subsample of probands providing familial DNA. Standard parametric tests were used to compare childhood ADD symptoms and maximal lifetime BMI across the two genotypic groups defined by the presence or absence of 7R. The TDT found no initial evidence for an association between 7R and the categorical diagnosis of SAD. However, 7R carriers reported significantly greater inattention and dysphoria in childhood (p=0.01 and 0.001, respectively) and a higher maximal lifetime BMI (p=0.007) than did probands without this allele. Furthermore, excluding probands with extreme obesity (maximal BMI >40), a strong correlation was found linking childhood inattentive symptoms and maximal lifetime BMI (r=0.35, p=0.001). In overeating women with SAD, the 7R allele of DRD4 may be associated with a unique developmental trajectory characterized by attentional deficits and dysphoria in childhood and mild to moderate obesity in adulthood. This developmental course may reflect different manifestations of the same underlying vulnerability related to central dopamine dysfunction. Given the possibility of population stratification when studying genotype/phenotype relationships, future use of genomic controls and replication of our findings in other overeating and/or ADD populations are needed to confirm these initial results.

BDNF and COMT Polymorphisms: Relation to Memory Phenotypes in Young Adults With Childhood-Onset Mood Disorder

Recent investigations in several species have suggested a role for brain-derived neurotrophic factor (BDNF) in memory, which may be mediated by the influence of BDNF on neuronal plasticity in the hippocampus. BDNF polymorphisms have also been associated with mood disorders. Catechol-O-methyltransferase (COMT) metabolizes dopamine and has been implicated in prefrontal function, another area of the brain relevant for memory. In a sample of 63 young adults with a history of childhood-onset mood disorder, we typed three BDNF polymorphisms, including the BDNF Val66Met single nucleotide polymorphism (SNP), and the COMT Val108/158Met SNP. Multivariate analysis of variance was used to test the association between BDNF and COMT markers and measures of declarative memory. Variants at the three BDNF markers and one COMT marker were not associated with declarative memory function p-values ranged from 0.25 to 0.98. Higher IQ (F = 6.18, df = 4, 58, p = 0.0003) and female gender (F = 4.41, df = 4, 58, p = 0.0035) were associated with more optimal performance on the memory tasks. This study did not provide evidence supporting an association between BDNF and COMT genes and declarative memory phenotypes.

Investigation of polymorphism in the MDR1 gene and antidepressant-induced mania

The involvement of the multi-drug-resistant 1 P-glycoprotein gene (MDR1 P-gp) in the transport of antidepressants across the blood-brain barrier makes it a good candidate for the prediction of antidepressant response and side effects. We investigated the role of the MDR1 P-gp gene in predicting the induction of mania in bipolar patients (BP) treated with proserotonergic drugs. Participants met the DSM-IV criteria for BP or BPII and had at least one depressive episode treated with proserotonergic antidepressants. The first group (n=26) included patients with at least one DSM-IV manic/hypomanic episode developed during antidepressant treatment; the second group (N=29) included patients with no antidepressant-induced switches. The common polymorphism of the MDR1 was genotyped for both groups and comparison was made with respect to the presence/absence of induced mania between the two groups. No association between antidepressant-induced mania and the MDR1 alleles or genotypes was found (chi2=1.85, 2 df, P=0.39; chi2=0.13, 1 df, P=0.72).

Guidelines and algorithms for the use of methylphenidate in children with Attention-Deficit/ Hyperactivity Disorder

OBJECTIVE

To review published algorithms for guiding the use of methylphenidate (MPH) in the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD) in children and adolescents.

METHODS

A consensus roundtable of 12 experts was convened to review the evidence for the safety and efficacy of MPH in the treatment of ADHD, as well as the published algorithms and practice guidelines for using MPH. The experts reviewed the algorithms for practicality and acceptability by clinicians.

RESULTS

Algorithms that included MPH commonly selected it as the initial medication to be employed in the treatment of children with ADHD. Factors involved included its high efficacy, good safety record, and the ubiquitous nature of its appearance in the ADHD treatment literature.

CONCLUSIONS

MPH should be considered as the first medication to be used in a treatment algorithm for children and adolescents with ADHD.

Association and linkage disequilibrium between a functional polymorphism of the dopamine-2 receptor gene and schizophrenia in a genetically homogeneous Portuguese population

A functional polymorphism in the promoter region of the DRD2 gene has been found to be associated with schizophrenia in Japanese(1,2) and Swedish populations.(3) We attempted to replicate these findings in a genetically homogeneous Portuguese population using a family-based study design. Analysis of 78 trios revealed evidence for association between the -141 C Ins allele and schizophrenia using the haplotype relative risk (HRR) method (chi(2) = 9.30, P = 0.0023). Further examination of this sample using an alternative family-based association analysis method, the transmission disequilibrium test (TDT), of 33 informative matings from the Portuguese trios provided evidence for an allelic association and linkage disequilibrium between the insertion allele and schizophrenia (chi(2) = 8.76, P = 0.0031). These consistent results using two alternative family-based association analysis methods replicate the findings of previous reports, and thus further implicate a potential role for the dopamine-2 receptor in the genetic etiology of schizophrenia.