Transmission disequilibrium and haplotype analyses of the G72/G30 locus: suggestive linkage to schizophrenia in Palestinian Arabs living in the North of Israel.

Association of the G72/G30 locus with schizophrenia was recently reported in French Canadian, Russian, and Ashkenazi populations using case-control studies. In the present study we hypothesize the existence of a G72/G30 risk allele over-transmitted to affected sibs in Palestinian Arab families. A total of 223 Palestinian Arab families that included an affected offspring and parents were genotyped with 11 SNPs encompassing the G72/G30 genes. The families were recruited from three regions of Israel: 56 from the North (Afula), 136 from the central hill region (Bethlehem, Palestinian Authority), and 31 from the South (Beersheva). Individual SNP analyses disclosed a risk allele in SNP rs3916970 by both haplotype relative risk (HRR: chi(2) = 5.59, P = 0.018) and transmission disequilibrium test (TDT: chi(2) = 6.03, P = 0.014) in the Afula families. Follow-up multilocus analysis using family-based association tests (FBAT: z = 2.197, P = 0.028) exposed the adjacent haplotype. SNP rs3916970 is located about 8 kb from the linkage disequilibrium block that was reported to be associated with schizophrenia in Ashkenazi Jews. Excess of similar haplotypes of this region was observed in the Palestinian Arabs and the Ashkenazi patients. These data suggest a common risk factor for schizophrenia susceptibility in the G72/G30 locus among Ashkenazi Jews and Palestinian Arabs. The results strengthen previous reports on the role of this locus in the etiology of schizophrenia.

Is the WKL1 gene associated with schizophrenia?

A missense mutation Leu309Met in the WKL1 (MLC1, KIAA0027) gene, mapped to 22q13.3, was reported to co-segregate with periodic catatonic schizophrenia (SCZ) in a single large German pedigree with seven affected individuals (Meyer et al. [2001: Mol Psychiatry 6:302-306]). This report raised the following questions that were dealt with in the present study: does the Leu309Met mutation have a role in SCZ, or only in catatonic SCZ? Does the mutation Leu309Met in the WKL1 gene, encoding a putative membrane protein, non-selective cation channel, have any effect on the channel activity? Is the WKL1 gene, which is expressed exclusively in brain, expressed differently in SCZ brains compared to controls? These questions were answered by screening the Leu309Met mutation in 117 Israeli Jewish patients with SCZ (55 Ashkenazi and 62 non-Ashkenazi Jews) and 176 matched controls. In search of differences in the level of WKL1 gene expression, postmortem dorsalateral prefrontal cortex of 16 schizophrenic patients and 15 controls was checked. We also measured the putative channel activity of normal WKL1 subcloned in pcDNA3 to determine the effect of the reported Leu309Met mutation. Our results argue against the involvement of WKL1 in SCZ susceptibility.

Cytokine production and treatment response in major depressive disorder.

In a controlled study, such immunological parameters as whole blood production of the cytokines interleukin-6 (IL-6) and tumor-necrosis factor-alpha (TNF-alpha) were assessed in 24 inpatients with a major depressive disorder (MDD) both before and again under treatment. After a 6-week treatment period with amitriptyline, patients were classified as responders or nonresponders according to their psychopathological outcome as evaluated by the Hamilton and the Montgomery-Asberg Depression Rating Scales. Pre-treatment levels of c-reactive protein (CRP) were significantly higher in both patient subgroups than in the control subjects. In comparison to the controls, unstimulated pretreatment production of IL-6 was significantly decreased in the responders; whereas it was significantly increased in the nonresponder subgroup. Post-treatment values did not differ significantly among the patient and control groups. Pretreatment levels of TNF-alpha were increased in both patient subgroups, with a significant decrease during treatment only in the responder subgroup. Pretreatment levels of IL-6/10(5) mononuclear cells and the ratio between lymphocytes and monocytes acted as independent variables with regard to the clinical response. Our data indicate that unstimulated secretion of TNF-alpha is related to the psychopathological improvement; whereas, IL-6 levels might dichotomize the patients into subsequent responders and nonresponders already at admission.

Regulation of glucocorticoid receptor-mRNA in human blood cells by amitriptyline and dexamethasone.

Recent research suggests that antidepressants exert their clinical action in depression via the restoration of glucocorticoid receptor (GR) function with a subsequent normalization of the altered feed-back regulation of the hypothalamic-pituitary adrenocortical (HPA) system. We, therefore, studied the effects of amitriptyline, a standard antidepressant, and of the glucocorticoid dexamethasone, which has recently been reported to possess antidepressive properties, on glucocorticoid receptor mRNA (GR-mRNA) derived from blood cells of healthy male volunteers. Whole blood samples were exposed in vitro for 24 h to amitriptyline and dexamethasone, the mRNA was extracted, transcripts of the 'house-keeping gene' glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the GR-gene were subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) and semiquantitatively determined by subsequent densitometry. In a concentration of 10 nM, amitriptyline induced a significant increase in GR-mRNA (GR/GAPDH ratio) to 186 +/- 31% of the control condition, while a concentration of 10 microM of amitriptyline resulted in an increase of GR-mRNA (GR/GAPDH ratio) to 165 +/- 36%. Dexamethasone also up-regulated blood cell GR-mRNA (GR/GAPDH ratio) levels at a concentration of 10 nM to 184 +/- 29%, whereas an incubation with 10 microM apparently resulted in toxic effects on blood cells with a decreased amount of total mRNA samples recovered. In conclusion, we here show an increase of GR-mRNA in human blood cells after treatment with amitriptyline and dexamethasone, pointing to a direct action of these substances on GR-gene expression in a human system.