Genetic clustering of European cancer patients indicates that opioid-mediated pain relief is independent of ancestry.

The European Pharmacogenetic Opioid Study (EPOS) of a large series of European cancer patients treated with opioids was carried out to assess the influence of genetics on cancer pain relief. As response to opioid therapy was associated with the patients' country of origin, we tested whether population stratification might represent a confounding factor in the analysis of genetic control of response to opioid therapy. From the whole EPOS series representing 2294 patients' genotypes for 379 single-nucleotide polymorphisms (SNPs), we extracted 117 autosomal SNPs with minor allele frequency>0.28 to obtain highly informative genetic markers, and analyzed the SNPs in 1724 individuals showing <20% missing genotypes. Use of the AWclust program to detect clusters of genetically related individuals in the EPOS series showed that the 117-SNP panel distinguished four main European subgroups statistically associated with ethnicity, but not with country of origin or with the pain relief phenotype. Subethnic European groups of genetically related individuals exist that can be correctly identified using an ∼100-SNP panel. Such genetic clustering may control for admixture in association studies and may allow discrimination between genetic and environmental effects on phenotypes showing association with country of origin, as in the case of pain relief.

Is there a genetic cause for cancer cachexia? - a clinical validation study in 1797 patients.

BACKGROUND: Cachexia has major impact on cancer patients' morbidity and mortality. Future development of cachexia treatment needs methods for early identification of patients at risk. The aim of the study was to validate nine single-nucleotide polymorphisms (SNPs) previously associated with cachexia, and to explore 182 other candidate SNPs with the potential to be involved in the pathophysiology. METHOD: A total of 1797 cancer patients, classified as either having severe cachexia, mild cachexia or no cachexia, were genotyped. RESULTS: After allowing for multiple testing, there was no statistically significant association between any of the SNPs analysed and the cachexia groups. However, consistent with prior reports, two SNPs from the acylpeptide hydrolase (APEH) gene showed suggestive statistical significance (P=0.02; OR, 0.78). CONCLUSION: This study failed to detect any significant association between any of the SNPs analysed and cachexia; although two SNPs from the APEH gene had a trend towards significance. The APEH gene encodes the enzyme APEH, postulated to be important in the endpoint of the ubiquitin system and thus the breakdown of proteins into free amino acids. In cachexia, there is an extensive breakdown of muscle proteins and an increase in the production of acute phase proteins in the liver.

Influence from genetic variability on opioid use for cancer pain: a European genetic association study of 2294 cancer pain patients.

Cancer pain patients need variable opioid doses. Preclinical and clinical studies suggest that opioid efficacy is related to genetic variability. However, the studies have small samples, findings are not replicated, and several candidate genes have not been studied. Therefore, a study of genetic variability with opioid doses in a large population using a confirmatory validation population was warranted. We recruited 2294 adult European patients using a World Health Organization (WHO) step III opioid and analyzed single nucleotide polymorphisms (SNPs) in genes with a putative influence on opioid mechanisms. The patients' mean age was 62.5 years, and the average pain intensity was 3.5. The patients' primary opioids were morphine (n=830), oxycodone (n=446), fentanyl (n=699), or other opioids (n=234). Pain intensity, time on opioids, age, gender, performance status, and bone or CNS metastases predicted opioid dose and were included as covariates. The patients were randomly divided into 1 development sample and 1 validation sample. None of 112 SNPs in the 25 candidate genes OPRM1, OPRD1, OPRK1, ARRB2, GNAZ, HINT1, Stat6, ABCB1, COMT, HRH1, ADRA2A, MC1R, TACR1, GCH1, DRD2, DRD3, HTR3A, HTR3B, HTR2A, HTR3C, HTR3D, HTR3E, HTR1, or CNR1 showed significant associations with opioid dose in both the development and the validation analyzes. These findings do not support the use of pharmacogenetic analyses for the assessed SNPs to guide opioid treatment. The study also demonstrates the importance of validating findings obtained in genetic association studies to avoid reporting spurious associations as valid findings. To elicit knowledge about new genes that influence pain and the need for opioids, strategies other than the candidate gene approach is needed.

[Lamotrigine in the treatment of mental disorders]. / Lamotrigin i behandling av psykiatriske lidelser.

BACKGROUND: Bipolar and other mood disorders often do not respond satisfactorily to lithium, valproate, carbamazepine or antidepressants. MATERIAL AND METHODS: On the basis of six years of clinical experience with lamotrigine in the treatment of psychiatric disorders, supplemented by three case reports and a comprehensive literature review of empirical studies, we discuss the possible indications for lamotrigine in psychiatric disorders. RESULTS: Lamotrigine seems to have a stronger antidepressant effect in bipolar 1 disorders than gabapentine, carbamazepine and valproate, but a weaker effect on manic symptomatology than the latter two. Lamotrigine may be of value in the treatment of bipolar 2 disorders in which chronic treatment resistant depression is often a complication, including rapid cycling and, in the unipolar version of rapid cycling, brief recurrent depression. We have also used to good effect the neuroprotective effects of lamotrigine in prophylactic treatment of neurodegenerative disorders (e.g. Huntington's chorea). INTERPRETATION: Lamotrigine is an anticonvulsant with an efficacy profile in psychiatric disorders different from those of valproate, carbamazepine and gabapentine. The drug represents an important supplement to the treatment options in chronic recurrent mood and neuropsychiatric disorders.