These data suggest that there could be a familial relationship between the predispositions to schizophrenia and to major depression. We discuss a number of alternative hypotheses about the nature of this possible relationship.

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Disturbed circadian rhythms have been observed in seasonal affective disorder (SAD). The aim of this study was to further investigate this connection, and to test for potential association between polymorphisms in circadian clock-related genes and SAD, seasonality (seasonal variations in mood and behavior), or diurnal preference (morningness-eveningness tendencies). A total of 159 European SAD patients and 159 matched controls were included in the genetic analysis, and subsets were screened for seasonality (n ¼ 177) and diurnal preference (n ¼ 92). We found that diurnal preference was associated with both SAD and seasonality, supporting the hypothesis of a link between circadian rhythms and seasonal depression. The complete case-control material was genotyped for polymorphisms in the CLOCK, Period2, Period3, and NPAS2 genes. A significant difference between patients and controls was found for NPAS2 471 Leu/Ser (w 2 ¼ 9.90, Bonferroni corrected P ¼ 0.035), indicating a recessive effect of the leucine allele on disease susceptibility (w 2 ¼ 6.61, Bonferroni corrected P ¼ 0.050). Period3 647 Val/Gly was associated with self-reported morningness-eveningness scores (n ¼ 92, oneway ANOVA: F ¼ 4.99, Bonferroni corrected P ¼ 0.044), with higher scores found in individuals with at least one glycine allele (t ¼ 3.1, Bonferroni corrected P ¼ 0.013). A second, population-based sample of individuals selected for high (n ¼ 127) or low (n ¼ 98) degrees of seasonality, was also genotyped for NPAS2 471 Leu/Ser. There was no significant difference between these seasonality extreme groups, and none of the polymorphisms studied were associated with seasonality in the SAD case-control material (n ¼ 177). In conclusion, our results suggest involvement of circadian clock-related polymorphisms both in susceptibility to SAD and diurnal preference.

The influence of genetic factors in schizophrenia has been convincingly demonstrated by family, twin and adoption studies, but the mode of transmission remains uncertain. The reported pattern of recurrence risks suggests a set of interacting loci. Based on prior evidence for linkage on chromosome 6p (K. Kendler, pers. comm.), we have scanned the short arm of chromosome 6 in 54 families for loci predisposing to schizophrenia, using 25 microsatellite markers spanning 60 centiMorgans (cM). Allele sharing identity by descent was examined in affected sib-pairs from these families, followed by multipoint sib-pair linkage analysis. Positive lod scores were obtained over a wide region (D6S470 to D6S271), with a maximum lod score of 2.2 occurring near D6S274, located in 6p22. However, we obtained a lod score of -2 at D6S296, the locus found by others to provide the greatest linkage evidence. At D6S274, we report a positive lod score as do Straub et al. (individually non-significant). A combined total lod of 3.6-4.0 suggests the possibility of a susceptibility locus in this region. However, methodological differences between our studies makes a firm conclusion difficult.

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High-dose methadone is well known to cause testosterone deficiency and sexual dysfunction in opioid-dependent men. Buprenorphine is a new drug for the pharmacotherapy of opioid dependence. Its influence on the gonadal axis has not been investigated to date. We therefore assayed testosterone, free testosterone, estradiol, SHBG, LH, FSH, and prolactin in 17 men treated with buprenorphine. Thirty-seven men treated with high-dose methadone and 51 healthy blood donors served as controls. Sexual function and depression were assessed using a self-rating sexual function questionnaire and the Beck Depression Inventory. Patients treated with buprenorphine had a significantly higher testosterone level [5.1 +/- 1.2 ng/ml (17.7 +/- 4.2 nmol/liter) vs. 2.8 +/- 1.2 ng/ml (9.7 +/- 4.2 nmol/liter); P < 0.0001] and a significantly lower frequency of sexual dysfunction (P < 0.0001) compared with patients treated with methadone. The testosterone level of buprenorphine-treated patients did not differ from that of healthy controls. In conclusion, we demonstrated for the first time that buprenorphine, in contrast with high-dose methadone, seems not to suppress plasma testosterone in heroin-addicted men. To this effect, buprenorphine was less frequently related to sexual side effects. Buprenorphine might therefore be favored in the treatment of opioid dependence to prevent patients from the clinical consequences of methadone-induced hypogonadism.

The action of antipsychotic drugs on dopamine receptors suggests that dopaminergic signal transmission may play a role in the development of schizophrenia. We tested eight candidate genes (coding for dopamine receptors, the dopamine transporter, and G-proteins) in 59 families from Germany and Israel, for association. A P value of .00055 (.0044 when corrected for the no. of markers tested) was obtained for the intronic CA-repeat marker G-olfalpha on chromosome 18p. The value decreased to .000088 (.0007) when nine sibs with recurrent unipolar depressive disorder were included. Linkage analysis using SSLP markers densely spaced around G-olfalpha yielded a maximum two-point LOD score of 3.1 for a marker 0.5 cM distal to G-olfalpha. Multipoint analysis under the assumption of heterogeneity supported this linkage-whether the affected pheotype was defined narrowly or broadly-as did nonparametric linkage (NPL). In 12 families with exclusively maternal transmission of the disease, the NPL value also supported linkage to this marker. In order to test for association/linkage disequilibrium in the presence of linkage, the sample was restricted to independent offspring. When this sample was combined with 65 additional simplex families (each of them comprising one schizophrenic offspring and his or her parents), the 124-bp allele of G-olfalpha was transmitted 47 times and was not transmitted 21 times (P=.009). These results suggest the existence, on chromosome 18p, of a potential susceptibility locus for functional psychoses.

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