Functional MxA promoter polymorphism associated with subacute sclerosing panencephalitis

BACKGROUND

The antivirally active MxA protein is induced by interferon (IFN) alpha/beta and inhibits the replication of single-stranded RNA viruses including measles virus (MV). The authors investigated whether the MxA gene contributed to the development of subacute sclerosing panencephalitis (SSPE) in Japanese individuals.

METHODS

Single-nucleotide polymorphisms (SNP) in the promoter region of the MxA gene were screened, association studies were performed between two SNP and SSPE, and then a functional difference in the promoter activities of the two SNP was investigated by a dual luciferase reporter assay.

RESULTS

Four SNP were found (-88 G/T, -123 C/A, -200 T/C, and -213 G/T), and SSPE patients exhibited a higher frequency of both the -88T allele and the -88TT genotype than controls (p = 0.040 and 0.003). The IFN-induced up-regulation of the MxA promoter activity of the sequence with -88T was found to be significantly higher than that with G.

CONCLUSIONS

MxA promoter -88 G/T SNP may confer host genetic susceptibility to SSPE in Japanese individuals. The finding that homozygotes of the MxA -88T allele with a high MxA-producing capability were more frequently seen in SSPE patients suggests that the MxA protein promotes the establishment of persistent MV infection of neural cells.

Association study between CD30 and CD30 ligand genes and type 1 diabetes in the Japanese population

CD30-CD30 ligand (CD30L) signal transduction appears to protect against autoimmune diabetes by preventing expansion of autoreactive T cells and suppressing Th1-cytokine response. The purpose of this study was to determine whether CD30 or CD30L genes serve as a novel susceptibility gene for type 1 diabetes in humans. We screened CD30 and CD30L genes for polymorphisms in Japanese patients with type 1 diabetes and control subjects. Then, association studies were performed between each of the identified polymorphisms and type 1 diabetes. Direct-sequencing analysis of the CD30 and CD30L genes revealed four polymorphisms: one in the CD30 gene (-201G/A from the transcription start site), and three in the CD30L gene [CA repeat in the promoter, 276G/A in the exon 3, -73T/C in the intron 3 (IVS3 -73T/C)]. Association studies revealed no association between the CD30 and CD30L genes and type 1 diabetes in the whole population. In the female and male subpopulations, however, the frequency of (CA)(9) allele of the CD30L gene promoter or T allele of IVS3 -73T/C polymorphism in the CD30L gene was slightly higher in female patients with type 1 diabetes than that in control females. In conclusion, we could not find significant association between CD30 or CD30L genes and type 1 diabetes, but (CA)(9) allele in the promotor or T allele of -73T/C in intron 3 in CD30L gene might play a minor role in the pathogenesis of type 1 diabetes, only in the Japanese female population.