Copy number variations of chromosome 16p13.1 region associated with schizophrenia

Deletions and reciprocal duplications of the chromosome 16p13.1 region have recently been reported in several cases of autism and mental retardation (MR). As genomic copy number variants found in these two disorders may also associate with schizophrenia, we examined 4345 schizophrenia patients and 35,079 controls from 8 European populations for duplications and deletions at the 16p13.1 locus, using microarray data. We found a threefold excess of duplications and deletions in schizophrenia cases compared with controls, with duplications present in 0.30% of cases versus 0.09% of controls (P=0.007) and deletions in 0.12 % of cases and 0.04% of controls (P>0.05). The region can be divided into three intervals defined by flanking low copy repeats. Duplications spanning intervals I and II showed the most significant (P = 0.00010) association with schizophrenia. The age of onset in duplication and deletion carriers among cases ranged from 12 to 35 years, and the majority were males with a family history of psychiatric disorders. In a single Icelandic family, a duplication spanning intervals I and II was present in two cases of schizophrenia, and individual cases of alcoholism, attention deficit hyperactivity disorder and dyslexia. Candidate genes in the region include NTAN1 and NDE1. We conclude that duplications and perhaps also deletions of chromosome 16p13.1, previously reported to be associated with autism and MR, also confer risk of schizophrenia.

Protective factors associated with American Indian adolescents' safer sexual patterns

OBJECTIVES

This paper presents findings from a research partnership with rural American Indian communities to identify protective factors associated with their adolescents' health-related behaviors including 1) delay of sexual debut; 2) not having had intercourse in the past 3 months; 3) birth control use among sexually active adolescents in the past 3 months; 4) condom use in the past 3 months. Our goal was to identify salient characteristics of students and their perceptions of family, school, and friends which could be incorporated or supported in future program planning for adolescents.

METHODS

A written survey was administered to 484 Indian students in Grades 6-12 from five rural schools. The survey measured several potential protective factors identified by Problem Behavior Theory, along with self-efficacy and cultural interest and knowledge. Logistic regression assessed the relationship of the protective factors and positive sexual behaviors.

RESULTS

Factors significantly associated with abstention from intercourse and/or consistent use of birth control included perceived lower health-risk behavior of friends, higher perceived parental support, higher perceived parental knowledge and monitoring of the adolescent's activities and friends, a higher value on scholastic achievement, higher reported academic performance, and higher self-efficacy for safer sexual behaviors.

CONCLUSIONS

This research suggests that Indian adolescents have several protective factors indigenous to their communities which are modifiable. Building on the unique cultural heritage of Indian communities, many of these factors may be addressed through community planned prevention programs.

Lack of association between apolipoprotein E genoype and ischaemic stroke in a Scottish population

BACKGROUND

Apolipoprotein E epsilon4 allele has been associated with increased risk of coronary heart disease, and is also a major genetic susceptibility locus for Alzheimer's disease. Some studies have shown an association between apoE genotype and ischaemic stroke or outcome following stroke, while other studies have failed to do so. Materials and methods Using PCR and the Taqman fluorescence system to detect polymorphisms we examined apoE genotype in 266 ischaemic stroke cases and in a control population.

RESULTS

We found no association between apoeE epsilon 4 allele distribution and ischaemic stroke, or with outcome following stroke as measured using the Rankin score. Conclusion This study disagrees with a recent meta-analysis, and suggests that further studies are required to clarify the exact relationship between apoE genotype and ischaemic stroke.

The -141C Ins/Del polymorphism of the dopamine D2 receptor gene is not associated with either migraine or Parkinson's disease

Abnormalities in dopamine neurotransmission at the dopamine D2 receptor (DRD2) have been implicated in both migraine and Parkinson's disease. Positive associations have also been found between polymorphisms within the DRD2 gene and both of these conditions. The -141C Ins/Del polymorphism in the DRD2 receptor gene is a putative functional polymorphism. The purpose of this study was to determine whether it and any genes in linkage disequilibrium with this marker are involved in either of these conditions. We have compared the genotype and allele frequencies of the -141C Ins/Del polymorphism in 200 migraineurs and 260 Parkinson's disease cases with 464 controls. We have found no association between the receptor gene and either condition (P = 0.89 and P = 0.56 respectively). Our findings do not support the hypothesis that this polymorphism is involved in the aetiology of migraine or Parkinson's disease.

Apolipoprotein E is a genetic risk factor for fetal iodine deficiency disorder in China

Fetal iodine deficiency disorder (FIDD) is the principal form of endemic cretinism, and the most common cause of preventable mental deficiency in the world. However not everyone at risk develops FIDD and familial aggregation is common. This suggests that genetic factors may also be involved. The Apolipoprotein E (APOE) gene encodes for a lipoprotein that possesses a thyroid hormone binding domain, and APOE genotype may affect the efficiency with which thyroid hormone influences neuronal cell growth during the first and second trimesters of fetal development. We have compared ApoE genotypes in 91 FIDD cases with 154 local control subjects, recruited from three iodine deficiency areas in central China. We have also genotyped 42 FIDD family cases and 158 normal individuals from the families of local controls, and 375 population controls from Shanghai. APOE epsilon4 genotypes were significantly enriched in FIDD probands from each of the three iodine deficiency areas; the epsilon4 allele frequency was 16% vs 6% in controls. The same effect was also observed when we compared FIDD family cases with controls and control families. Our data suggest that in iodine-deficient areas, the APOE epsilon4 allele is a genetic risk factor for FIDD. The phenomenon may affect population selection and contribute to the low frequency of the epsilon4 allele in Chinese compared to Caucasian populations.

[Association of VNTR region of the human serotonin transporter gene with bipolar disorder among the Han Chinese]

OBJECTIVE

The serotonin transporter gene (SERT) plays an important role in the serotonin uptake into neurons. This paper reports a population and association study among the Han Chinese.

METHODS

DNA were extracted from peripheral blood samples of 50 patients with bipolar disorder (DSM-IIIR), 170 unrelated healthy Han Chinese individuals and 10 healthy trios for polymerase chain reaction. The VNTR locus was amplified and PCR products were separated on the 2% agrose gel.

RESULTS

All the three alleles(9,10 and 12 copies of repeat unit) reported in other studies were observed in this study with frequency 0.0029, 0.0676 and 0.9294, respectively. Four genotypes distributed in Caucasian: 12/12, 12/10, 12/9 and 10/10 were also found in the Han Chinese population. A significant difference in the allele frequency between the Han Chinese and Caucasian populations was found(P 0.000000001). No disequilibrium was observed after checking the Hardy-Weinberg equilibrium (P=0. 9995). The hereditary stability of this locus in accordance with the rules of Mendelian inheritance was demonstrated in the analysis of ten trios. In addition, a significant increase of frequency of the allele 10 in female patients with bipolar disorder was found (P=0. 043).

CONCLUSION

The data of association study might indicate a different mechanism of aetiology of bipolar disorder in male and female.