Mutational analysis of Peroxiredoxin IV: exclusion of a positional candidate for multinodular goitre
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Background Multinodular goitre (MNG) is a common disorder characterised by an enlargement of the thyroid, occurring as a compensatory response to hormonogenesis impairment. The incidence of MNG is dependent on sex (female:male ratio 5:1) and several reports have documented a genetic basis for the disease. Last year we mapped a MNG locus to chromosome Xp22 in a region containing the peroxiredoxin IV (Prx-IV) gene. Since Prx-IV is involved in the removal of H2O2 in thyroid cells, we hypothesize that mutations in Prx-IV gene are involved in pathogenesis of MNG. Methods Four individuals (2 affected, 2 unrelated unaffected) were sequenced using automated methods. All individuals were originated from the original three-generation Italian family described in previous studies. A Southern blot analysis using a Prx-IV full-length cDNA as a probe was performed in order to exclude genomic rearrangements and/or intronic mutations. In addition a RT-PCR of PRX-IV was performed in order to investigate expression alterations. Results No causative mutations were found. Two adjacent nucleotide substitutions were detected within introns 1 and 4. These changes were also detected in unaffected individuals, suggesting that they were innocuous polymorphisms. No gross genomic rearrangements and/or restriction fragment alterations were observed on Southern analysis. Finally, using RT-PCR from tissue-specific RNA, no differences of PRX-IV expression-levels were detected between affected and unaffected samples. Conclusions Based on sequence and genomic analysis, Prx-IV is very unlikely to be the MNG2 gene.
The (CTG)n polymorphism in the NOTCH4 gene is not associated with schizophrenia in Japanese individuals
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Background The human NOTCH4 gene is a candidate gene for schizophrenia due to its chromosomal location and neurobiological roles. In a British linkage study, NOTCH4 gene polymorphisms were highly associated with schizophrenia. In a Japanese case-control association study, however, these polymorphisms did not show significant associations with schizophrenia. We conducted a case-control study with Japanese subjects to explore an association between the triplet repeat polymorphism in the NOTCH4 gene and schizophrenia, including subtypes of schizophrenia, longitudinal disease course characteristics, and a positive family history for psychoses. Methods We examined the (CTG)n repeat polymorphism in the NOTCH4 gene among 100 healthy Japanese individuals and 102 patients with schizophrenia (22 paranoid, 38 disorganized, 29 residual, 64 episodic, 31 continuous, 42 with prominent negative symptoms, and 46 with positive family histories) using a polymerase chain reaction-based, single-strand conformational polymorphism analysis. Results Five different alleles consisting of 6, 9, 10, 11, and 13 repeats of CTG (Leu) in patients with schizophrenia, and 4 alleles consisting of 6, 9, 10, and 11 repeats in controls were found. No significant differences in genotype or allele frequencies of repeat numbers were found between controls and patients. In addition, there were no associations between the polymorphism and schizophrenia subtypes, longitudinal disease course characteristics, or positive family history of the patients. Conclusions Our data suggest a lack of association between the NOTCH4 gene triplet repeat polymorphism and schizophrenia in Japanese individuals.
The human homologue of
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Background In sporadic ovarian cancer, we have previously reported allele loss at D6S193 (62%) on chromosome 6q27, which suggested the presence of a putative tumour suppressor gene. Based on our data and that from another group, the minimal region of allele loss was between D6S264 and D6S149 (7.4 cM). To identify the putative tumour suppressor gene, we established a physical map initially with YACs and subsequently with PACs/BACs from D6S264 to D6S149. To accelerate the identification of genes, we sequenced the entire contig of approximately 1.1 Mb. Seven genes were identified within the region of allele loss between D6S264 and D6S149. Results The human homologue of unc-93 (UNC93A) in C. elegans was identified to be within the interval of allele loss centromeric to D6S149. This gene is 24.5 kb and comprises of 8 exons. There are two transcripts with the shorter one due to splicing out of exon 4. It is expressed in testis, small intestine, spleen, prostate, and ovary. In a panel of 8 ovarian cancer cell lines, UNC93A expression was detected by RT-PCR which identified the two transcripts in 2/8 cell lines. The entire coding sequence was examined for mutations in a panel of ovarian tumours and ovarian cancer cell lines. Mutations were identified in exons 1, 3, 4, 5, 6 and 8. Only 3 mutations were identified specifically in the tumour. These included a c.452G>A (W151X) mutation in exon 3, c.676C>T (R226X) in exon 5 and c.1225G>A(V409I) mutation in exon 8. However, the mutations in exon 3 and 5 were also present in 6% and 2% of the normal population respectively. The UNC93A cDNA was shown to express at the cell membrane and encodes for a protein of 60 kDa. Conclusions These results suggest that no evidence for UNC93A as a tumour suppressor gene in sporadic ovarian cancer has been identified and further research is required to evaluate its normal function and role in the pathogenesis of ovarian cancer.