Genome-wide association study of 40,000 individuals identifies two novel loci associated with bipolar disorder

Bipolar disorder (BD) is a genetically complex mental illness characterized by severe oscillations of mood and behaviour. Genome-wide association studies (GWAS) have identified several risk loci that together account for a small portion of the heritability. To identify additional risk loci, we performed a two-stage meta-analysis of >9 million genetic variants in 9,784 bipolar disorder patients and 30,471 controls, the largest GWAS of BD to date. In this study, to increase power we used ∼2,000 lithium-treated cases with a long-term diagnosis of BD from the Consortium on Lithium Genetics, excess controls, and analytic methods optimized for markers on the X-chromosome. In addition to four known loci, results revealed genome-wide significant associations at two novel loci: an intergenic region on 9p21.3 (rs12553324, P =  5.87 × 10 -  9; odds ratio (OR) = 1.12) and markers within ERBB2 (rs2517959, P =  4.53 × 10 -  9; OR = 1.13). No significant X-chromosome associations were detected and X-linked markers explained very little BD heritability. The results add to a growing list of common autosomal variants involved in BD and illustrate the power of comparing well-characterized cases to an excess of controls in GWAS.

Genetic variants associated with response to lithium treatment in bipolar disorder: a genome-wide association study

BACKGROUND

Lithium is a first-line treatment in bipolar disorder, but individual response is variable. Previous studies have suggested that lithium response is a heritable trait. However, no genetic markers of treatment response have been reproducibly identified.

METHODS

Here, we report the results of a genome-wide association study of lithium response in 2563 patients collected by 22 participating sites from the International Consortium on Lithium Genetics (ConLiGen). Data from common single nucleotide polymorphisms (SNPs) were tested for association with categorical and continuous ratings of lithium response. Lithium response was measured using a well established scale (Alda scale). Genotyped SNPs were used to generate data at more than 6 million sites, using standard genomic imputation methods. Traits were regressed against genotype dosage. Results were combined across two batches by meta-analysis.

FINDINGS

A single locus of four linked SNPs on chromosome 21 met genome-wide significance criteria for association with lithium response (rs79663003, p=1·37 × 10(-8); rs78015114, p=1·31 × 10(-8); rs74795342, p=3·31 × 10(-9); and rs75222709, p=3·50 × 10(-9)). In an independent, prospective study of 73 patients treated with lithium monotherapy for a period of up to 2 years, carriers of the response-associated alleles had a significantly lower rate of relapse than carriers of the alternate alleles (p=0·03268, hazard ratio 3·8, 95% CI 1·1-13·0).

INTERPRETATION

The response-associated region contains two genes for long, non-coding RNAs (lncRNAs), AL157359.3 and AL157359.4. LncRNAs are increasingly appreciated as important regulators of gene expression, particularly in the CNS. Confirmed biomarkers of lithium response would constitute an important step forward in the clinical management of bipolar disorder. Further studies are needed to establish the biological context and potential clinical utility of these findings.

FUNDING

Deutsche Forschungsgemeinschaft, National Institute of Mental Health Intramural Research Program.

No association of endocannabinoid genes with bipolar disorder or lithium response in a Sardinian sample

Bipolar disorder (BD) is a chronic and severe psychiatric condition with an underlying component of genetic susceptibility. Mounting evidence suggests a potential role of the endogenous cannabinoid (eCB) system in the pathogenesis of BD. Here we investigated the role of genes encoding for key eCB elements on the risk of developing BD in a sample of 357BD patients and 422 healthy controls of Sardinian ancestry. Using the HapMap CEU population SNP database, we selected 25 tag Single Nucleotide Polymorphisms (tSNPs) in N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD), cannabinoid receptor 1 (CNR1) and fatty acid amide hydrolase (FAAH) genes. No significant association was reported for FAAH or CNR1. SNPs rs11487077 and rs6465903 in NAPE-PLD showed nominal association (p=0.033 and p=0.026, respectively) with BD, not significant after permutation testing. These SNPs were also tested for association with lithium response in 204 BD patients characterized for response to long-term lithium treatment, reporting no significant findings. As a whole, our results do not support a clear role of FAAH, CNR1 and NAPE-PLD in BD and lithium response. Additional studies on independent, larger samples are warranted to further explore the involvement of the eCB system in BD.

Association study in three different populations between the GPR88 gene and major psychoses

GPR88, coding for a G protein-coupled orphan receptor that is highly represented in the striatum, is a strong functional candidate gene for neuropsychiatric disorders and is located at 1p22-p21, a chromosomal region that we have previously linked to bipolar disorder (BD) in the Sardinian population. In order to ascertain the relevance of GPR88 as a risk factor for psychiatric diseases, we performed a genetic association analysis between GPR88 and BD in a sample of triads (patient and both parents) recruited in the Sardinian and the Palestinian population as well as between GPR88 and schizophrenia (SZ) in triads from the Xhosa population in South Africa. We found a positive association between GPR88 and BD in the Sardinian and Palestinian triads. Moreover, we found a positive association between GPR88 and SZ in triads from the Xhosa population in South Africa. When these results were corrected for multiple testing, the association between GPR88 and BD was maintained in the Palestinian population. Thus, these results suggest that GPR88 deserves consideration as a candidate gene for psychiatric diseases and requires to be further investigated in other populations.

Genetic risk of suicidal behavior in bipolar spectrum disorder: analysis of 737 pedigrees

OBJECTIVES

Suicide is a significant cause of mortality in patients with major affective disorders (MAD), and suicidal behavior and MAD co-aggregate in families. However, the transmission of suicidal behavior is partially independent from that of MAD. We analyzed the lifetime prevalence of completed and attempted suicides in a large sample of families with bipolar disorder (BD), its relation to family history of MAD and BD, and the contribution of clinical and treatment factors to the risk of suicidal behavior.

METHODS

We studied 737 families of probands with MAD with 4919 first-degree relatives (818 affected, 3948 unaffected, and 153 subjects with no information available). Lifetime psychiatric diagnoses and suicidal behavior in first-degree relatives were assessed using semi-structured interviews, family history methods, and reviews of clinical records. Cox proportional hazard and logistic regression models were used to investigate the role of clinical covariates in the risk of suicidal behavior, and in the prevalence of MAD and BD.

RESULTS

The estimated lifetime prevalence of suicidal behavior (attempted and completed suicides) in 737 probands was 38.4 ± 3.0%. Lithium treatment decreased suicide risk in probands (p = 0.007). In first-degree relatives, a family history of suicidal behavior contributed significantly to the joint risk of MAD and suicidal behavior (p = 0.0006).

CONCLUSIONS

The liability to suicidal behavior is influenced by genetic factors (particularly family history of suicidal behavior and MAD). Even in the presence of high genetic risk for suicidal behavior, lithium treatment decreases suicide rates significantly.

Investigation of endocannabinoid system genes suggests association between peroxisome proliferator activator receptor-α gene (PPARA) and schizophrenia

Schizophrenia (SZ) is a complex psychiatric disorder with a large genetic burden and an estimated hereditability of 80%. A large number of neuroanatomical and psychopharmacological studies suggest a central role of the endocannabinoid (eCB) system in the susceptibility of the disease. To further investigate this hypothesis, we performed an association study with genes codifying for key elements of the eCB system in a sample of 170 schizophrenic patients and 350 healthy controls of Italian ancestry. A total of 57 Tag SNPs (tSNPs) were selected using HapMap CEU population SNP database spanning the following genes: cannabinoid receptor 1 (CNR1), peroxisome proliferator activator receptor-α (PPARA), fatty acid amide hydrolase (FAAH) and N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD). Seven out of the 32 tSNPs within PPARA (rs4253765, rs4263776, rs6007662, rs1800206, rs4253763, rs6008197 and rs4253655) and 3 out of 12 tSNPs within CNR1 (rs1049353, rs7766029 and rs806366) were nominally associated with SZ (uncorrected p<0.05). The same pattern of association was observed in the genotype analysis, with rs4253765 showing the highest level of significance (uncorrected p=2×10(-3)). None of these associations survived after permutation test. Our findings suggest a potential role for PPARA in the susceptibility to SZ, but further studies on larger independent samples are warranted in order to clarify the involvement of this gene in the pathophysiology of SZ.

Assessment of Response to Lithium Maintenance Treatment in Bipolar Disorder: A Consortium on Lithium Genetics (ConLiGen) Report

OBJECTIVE

The assessment of response to lithium maintenance treatment in bipolar disorder (BD) is complicated by variable length of treatment, unpredictable clinical course, and often inconsistent compliance. Prospective and retrospective methods of assessment of lithium response have been proposed in the literature. In this study we report the key phenotypic measures of the "Retrospective Criteria of Long-Term Treatment Response in Research Subjects with Bipolar Disorder" scale currently used in the Consortium on Lithium Genetics (ConLiGen) study.

MATERIALS AND METHODS

Twenty-nine ConLiGen sites took part in a two-stage case-vignette rating procedure to examine inter-rater agreement [Kappa (κ)] and reliability [intra-class correlation coefficient (ICC)] of lithium response. Annotated first-round vignettes and rating guidelines were circulated to expert research clinicians for training purposes between the two stages. Further, we analyzed the distributional properties of the treatment response scores available for 1,308 patients using mixture modeling.

RESULTS

Substantial and moderate agreement was shown across sites in the first and second sets of vignettes (κ = 0.66 and κ = 0.54, respectively), without significant improvement from training. However, definition of response using the A score as a quantitative trait and selecting cases with B criteria of 4 or less showed an improvement between the two stages (ICC1 = 0.71 and ICC2 = 0.75, respectively). Mixture modeling of score distribution indicated three subpopulations (full responders, partial responders, non responders).

CONCLUSIONS

We identified two definitions of lithium response, one dichotomous and the other continuous, with moderate to substantial inter-rater agreement and reliability. Accurate phenotypic measurement of lithium response is crucial for the ongoing ConLiGen pharmacogenomic study.

Insulin-like growth factor 1 (IGF-1) expression is up-regulated in lymphoblastoid cell lines of lithium responsive bipolar disorder patients

Bipolar disorder (BD) is a debilitating psychiatric disease characterized by alternating episodes of mania and depression. Among mood stabilizers, lithium is the mainstay for the treatment of BD, with approximately one-third of patients showing remission from episode recurrence. While there is evidence suggesting genetic load for lithium response in BD, its molecular underpinnings are still not completely understood. To identify genes potentially involved in (or correlated with) lithium response, we carried out a genome-wide expression analysis on lymphoblastoid cell lines (LCLs) from 10 BD patients responders (R) and 10 non-responders (NR) to lithium. We compared expression levels of the two groups and tested whether in vitro lithium treatment had different effects in LCLs of R compared to NR. At basal, 2060 genes were differentially expressed between R and NR while no genes were differentially regulated by lithium in the two groups. After pathway analysis based on the 2060 genes, 9 genes were selected for validation with qRT-PCR. Eight genes were validated in the same sample of LCLs while only insulin-like growth factor 1 (IGF-1) was significantly over-expressed in R compared to NR in the same sample as well as in an independent sample comprised of 6 R and 6 NR (sample 1, fold change=1.94; p=0.005; sample 2, fold change=2.21; p=0.005). IGF-1 was also significantly over-expressed in R but not in NR when compared to a sample of non-psychiatric controls. Our findings suggest that IGF-1 may be involved in lithium response, supporting further investigation on its potential as a biomarker.

Evidence for association of an ACCN1 gene variant with response to lithium treatment in Sardinian patients with bipolar disorder

AIMS

Bipolar disorder (BD) is a lifelong psychiatric illness characterized by manic and depressive episodes affecting 1-5% of the general population. Among mood-stabilizing treatments, lithium represents the mainstay in the therapeutic management of BD. However, besides the relatively high rate of excellent responders, a significant fraction of patients present patterns of partial or nonresponse to lithium. This variability might be influenced by genetic factors, even though findings have so far been inconclusive. Here, we present the results of an exploratory genome-wide scan followed by extended genotyping carried out on a sample of 204 Sardinian BD patients characterized for lithium response.

MATERIALS & METHODS

Phenotypic assessment of lithium response was made using the retrospective criteria of long-term treatment response scale. Using Affymetrix(®) 6.0 SNP arrays, we genotyped a subsample of 52 BD patients evenly distributed at the extreme ends of the treatment response scale. The associated SNPs were then prioritized and selected for validation and extended genotyping in the whole sample of BD patients characterized for lithium response. Association was also tested using the scale for a quantitative trait analysis.

RESULTS

Our findings showed that several SNPs were nominally associated (p ≤ 10(-5)) with lithium response in the subgroup of 52 BD subjects. Some association signals were then confirmed in the extended sample. The strongest association, also supported by the quantitative trait analysis, was shown for a SNP located in intron 1 of the ACCN1 gene, encoding for a cation channel with high affinity for sodium and permeable to lithium.

CONCLUSION

Our results indicate that ACCN1 gene is a potential candidate for response to lithium treatment that would serve as a genetic marker of lithium efficacy for BD patients.

Genome-scan for bipolar disorder with sib-pair families in the Sardinian population: a new susceptibility locus on chromosome 1p22-p21?

The discovery of the genetic factors implicated in the predisposition to complex diseases may greatly profit from genetic studies in isolated populations. In this perspective, we performed a genome-wide scan using 507 microsatellite markers, with an average interval size of 7.6 cM, on a sample of 88 nuclear families with at least two affected sibs with bipolar disorder recruited in the Sardinian population. An initial analysis yielded non-parametric linkage exceeding 3.4 with P-values <0.0003 at two adjacent markers, D1S206 and D1S435 in the 1p22-p21 chromosomal region. Moreover, positive linkage ranging between 2.0 and 3.0 was obtained for other loci in several cases in regions that have already been linked to predisposition to bipolar disorder, such as 5p15.33, 8q24.13, and 11q14.3. A subsequent analysis of the 1p22-p21 region using the same set of families and a dense panel of 20 new microsatellite markers, spaced at 1.2 cM on average, reinforced the finding of suggestive linkage for this region. Interestingly, NPL values above 2.1 and P-values <0.02 were obtained for a cluster of 10 markers comprising D1S435. Thus, this study suggests that the 1p22-p21 region may contain a new locus participating to the genetic susceptibility to bipolar disorder and reproduces positive linkage for several other loci already implicated in this pathology. Since the Sardinian population presents a peculiar genetic homogeneity, these results may pave the way to further studies for replication in this population contributing to the rapid discovery of the genetic factors predisposing to bipolar disorder.

Sensitivity to 6-n-propylthiouracil is associated with gustin (carbonic anhydrase VI) gene polymorphism, salivary zinc, and body mass index in humans

BACKGROUND

The individual ability to taste 6-n-propylthiouracil (PROP) may be correlated with body mass index (BMI) and differences in the salivary proteins involved in taste function, such as the zinc-dependent enzyme gustin, which is a trophic factor of taste buds.

OBJECTIVE

We investigated the possible association of PROP taste responsiveness with gustin gene polymorphism rs2274333 (A/G), salivary ionic zinc concentrations, and BMI.

DESIGN

We measured cognitive eating behaviors and BMI in 75 volunteers (28 men and 47 women; mean plusmn SEM age: 25 plusmn 3 y). The intensity of taste perception evoked by PROP and sodium chloride solutions was estimated to evaluate PROP taster status. Salivary ionic zinc concentrations were measured, and molecular analyses of the gustin gene polymorphism were performed in individuals classified by PROP status by using polymerase chain reaction techniques.

RESULTS

We classified subjects as PROP supertasters (n = 27), medium tasters (n = 28), or nontasters (n = 20). Salivary ionic zinc concentrations and BMI were greater in nontasters than in supertasters (P = 0.003 and P = 0.042, respectively). Molecular analyses of gustin DNA showed that allele A and genotype AA were significantly more frequent in supertasters, whereas allele G and genotype GG were significantly more frequent in nontasters (P lt 0.001).

CONCLUSIONS

These data showed that responsiveness to PROP is inversely related to BMI and salivary ionic zinc concentrations. The gustin gene dimorphism rs2274333 observed in supertaster and nontaster subjects may influence the protein conformation and, thereby, affect zinc ion binding. Our data showed a direct association between PROP sensitivity and a polymorphism in the gustin gene that is hypothesized to affect its function. This trial was registered at clinicaltrials.gov as UNICADBSITB-1.

The International Consortium on Lithium Genetics (ConLiGen): an initiative by the NIMH and IGSLI to study the genetic basis of response to lithium treatment

For more than half a decade, lithium has been successfully used to treat bipolar disorder. Worldwide, it is considered the first-line mood stabilizer. Apart from its proven antimanic and prophylactic effects, considerable evidence also suggests an antisuicidal effect in affective disorders. Lithium is also effectively used to augment antidepressant drugs in the treatment of refractory major depressive episodes and prevent relapses in recurrent unipolar depression. In contrast to many psychiatric drugs, lithium has outlasted various pharmacotherapeutic 'fashions', and remains an indispensable element in contemporary psychopharmacology. Nevertheless, data from pharmacogenetic studies of lithium are comparatively sparse, and these studies are generally characterized by small sample sizes and varying definitions of response. Here, we present an international effort to elucidate the genetic underpinnings of lithium response in bipolar disorder. Following an initiative by the International Group for the Study of Lithium-Treated Patients (www.IGSLI.org) and the Unit on the Genetic Basis of Mood and Anxiety Disorders at the National Institute of Mental Health,lithium researchers from around the world have formed the Consortium on Lithium Genetics (www.ConLiGen.org) to establish the largest sample to date for genome-wide studies of lithium response in bipolar disorder, currently comprising more than 1,200 patients characterized for response to lithium treatment. A stringent phenotype definition of response is one of the hallmarks of this collaboration. ConLiGen invites all lithium researchers to join its efforts.

No association between lithium full responders and the DRD1, DRD2, DRD3, DAT1, 5-HTTLPR and HTR2A genes in a Sardinian sample

Polymorphisms within the DRD1, DRD2, DRD3, DAT1, 5-HTTLPR and HTR2A genes are being studied for association with lithium prophylaxis in a sample of 155 Sardinian unrelated probands affected by bipolar disorder (BP). No significant association was shown between the polymorphisms of the genes studied and response to lithium treatment.

Association study in a Sardinian sample between bipolar disorder and the nuclear receptor REV-ERBalpha gene, a critical component of the circadian clock system

OBJECTIVE

The aim of our study was to investigate the association between REV-ERBalpha gene (NR1D1) single nucleotide polymorphisms (SNPs) and bipolar disorder (BP) in a case-control sample of Sardinian ancestry and evaluate its effect on age at onset (AAO) of BP.

METHODS

We genotyped SNPs rs12941497 (SNP1) and rs939347 (SNP2), located, respectively, in the first intron and in the 5'UTR region of the gene, in a sample comprised of 300 bipolar patients and 300 healthy controls of Sardinian ancestry. We also studied AAO by means of admixture analysis, obtaining a cutoff point of age 22 and then carrying out association analysis between the two AAO groups.

RESULTS

In the case-control comparison, single marker analysis showed no association for any of the SNPs tested. Haplotype analysis showed a nominally significant association for two haplotypes of SNPs 1-2. Comparing the early- and later-onset groups, nominal association was found for SNP1. Haplotype analysis showed that one haplotype was nominally associated with the later-onset group.

CONCLUSIONS

Our results, indicating a nominal association of the REV-ERBalpha gene with BP, suggest a possible role of REV-ERBalpha in the pathogenesis of BP. Further investigation of larger independent samples and different populations is warranted.

[Evaluation of lithium treatment response in Sardinian bipolar patients]

AIM

Bipolar disorder (BP) is a mood disorder with a prevalence of 1-2% in the general population. Lithium is the most widely used and best characterized long-term treatment for BP. The aim of this study is the evaluation of the effectiveness of lithium treatment in a naturalistic setting. Moreover we investigated if a number of clinical markers were positively or negatively associated with treatment response.

METHODS

We evaluated 199 outpatients affected by BP (according to DSM-IV criteria), who had continuously received lithium for at least one year. Life course of illness in each patient was graphically depicted with the NIMH Life Chart method which allowed us to apply the Retrospective Evaluation of Prophylactic Treatment Response Scale in order to assess the treatment outcome. This scale rates the degree of improvement in the course of treatment weighted by the likelihood of response being attributable to the treatment, rather than other factors.

RESULTS

Full Responders to lithium were 29% of the sample. Bipolar II (BPII) patients were significantly overrepresented in the Full Responders group (p = 0.035). In addition, psychotic symptoms were significantly associated to a poorer treatment outcome (p = 0.0197).

CONCLUSIONS

This study supports the effectiveness of lithium treatment in a naturalistic setting, suggesting that BPII patients could also benefit from lithium treatment. Finally, it suggests that the use of another mood stabilizer or of a combination treatment could represent a valuable therapeutic choice in the management of bipolar patients with psychotic symptoms.

Age at onset in Sardinian bipolar I patients: evidence for three subgroups

OBJECTIVE

We studied age at onset (AAO) in order to assess the presence of different subgroups in a homogeneous genetic population, such as the Sardinian population.

METHODS

Admixture analysis was applied in order to identify a model of separate normal distribution of AAO characterized by different means, variances and population proportions to allow for evaluation of different subgroups in a sample of 181 unrelated patients of Sardinian origin with bipolar disorder (BP) type I. The Mann-Whitney test was used to compare the means of AAO between subjects with a history of suicide attempts and subjects with no such history.

RESULTS

The best-fitting model had three components with means (SD) of 18.1 (2.3), 24.3 (5.3) and 41 (11.5) years, comprising 36%, 39% and 25% of the sample, respectively. We obtained two cut-off points at 21 and 33 years, enabling the sample to be divided into three subgroups. The Mann-Whitney test revealed a difference between the mean AAO of subjects with a positive history of suicide attempts and that of subjects with no such history (p = 0.041).

CONCLUSIONS

We found three AAO sub-groups in our sample of BP I patients of Sardinian origin. Our findings add further support to the hypothesis whereby AAO acts as a clinical marker of biological heterogeneity in BP.

Alzheimer's disease: case-control association study of polymorphisms in ACHE, CHAT, and BCHE genes in a Sardinian sample

Alzheimer's disease (AD) is characterized by an extensive loss of cholinergic neurons, and their cortical projections, from the basal forebrain area. The resulting reduction in cholinergic activity is associated with decreased levels of the neurotransmitter acetylcholine (ACh), decreased activity of acetylcholinesterase (AChE), choline acetyltransferase (ChAT), and increased butyrylcholinesterase (BChE) activity. In the present study, we investigated whether the BCHE, ACHE, and CHAT genes were associated with AD and the possibility of a synergistic effect with APOE-epsilon4 in a Sardinian sample. AD patients (n = 158), exclusively of Sardinian ancestry, were recruited from the Division of Geriatrics Local Health Agency 8 and Unit of Clinical Pharmacology, Department of Neurosciences, University of Cagliari. Patients were diagnosed according to DSM-IV, and National Institute of Neurologic and Communicative Disorders and Stroke-AD and Related Disorders Association (NINCDS-ADRDA) criteria for possible or probable AD. Cognitive screening was performed by means of Mini-Mental State Examination (MMSE). Healthy controls (n = 118) of Sardinian ancestry were recruited from religious and sport associations. All patients and control subjects gave informed consent for participation in the study. Single nucleotide polymorphism (SNP) analysis was performed by PCR/RFLP or the TaqMan 5' exonuclease method. Our study confirms the association between APOE epsilon4 allele and AD (P < 0.000). No significant differences were observed in allele and genotype frequencies of BCHE, ACHE, and CHAT between AD and controls. Haplotype analysis of ACHE SNPs did not reveal a significant association between ACHE and AD. Our results suggest that the AChE, ChAT, and BChE polymorphisms do not constitute a major genetic risk factor for susceptibility to AD in a Sardinian population.

A48G polymorphism in the D1 receptor genes associated with bipolar I disorder

Several lines of evidence point to a role for dopamine in mood disorders and, in particular, in bipolar disorders. In line with a considerable amount of evidence, the dopamine D1 receptor gene (DRD1) is considered to be a good candidate gene for bipolar disorders. Several studies did not find any association between bipolar 1 patients and DRD1. In this study, we investigate a possible association between BP disorder and -48A/G polymorphism of the DRD1. We genotyped 107 bipolar 1 patients and 129 healthy control subjects of exclusively Sardinian descent. A statistically significant difference in genotype (chi2 = 6.29, df = 2, P = 0.042) and allele (chi2 = 5.46, df=1, P = 0.019; OR = 1.53, 95% CI = 1.08-2.16) frequencies was found, suggesting an association between the DRD1 gene and bipolar I disorder (BP I) in the Sardinian population.

Adverse Reactions During Imatinib and Lansoprazole Treatment in Gastrointestinal Stromal Tumors

OBJECTIVE:

To report the case of a patient affected by gastrointestinal stromal tumors (GIST) who developed cutaneous adverse drug reactions during treatment with imatinib and lansoprazole.

CASE SUMMARY:

After 2 months of treatment with imatinib 400 mg/day, a 60-year-old white female affected by GIST developed bilateral palpebral edema with hyperemic conjunctivae and labial edema when lansoprazole 15 mg/day was introduced to treat dyspeptic symptomatology. Treatment was discontinued, and on reintroduction of both drugs, the patient developed Stevens—Johnson syndrome. Two months later, generalized cutaneous reactions appeared immediately following reintroduction of low-dose imatinib with corticosteroid plus lansoprazole treatment. After discontinuation of all drugs, with the exception of the corticosteroid, the progression of cutaneous lesions stopped.

DISCUSSION:

The use of imatinib is commonly associated with a high dose-dependent rate of rash and edema. Several cases of Stevens—Johnson syndrome have also been described, although not in patients affected by GIST. Severe skin reactions have been reported for lansoprazole including erythema multiforme, Stevens—Johnson syndrome, and toxic epidermal necrolysis. Applying Naranjo's algorithm, the adverse events were considered possible due to imatinib and probable due to lansoprazole.

CONCLUSIONS:

On the basis of the data reported, we conclude that the adverse reactions described may be attributed to either drug alone. However, combined use of drugs may increase the risk of onset of these adverse reactions due to a potential drug interaction involving CYP3A4.