Hirohiko Hohjoh

Complex HLA-DR and -DQ Interactions Confer Risk of Narcolepsy- Cataplexy in Three Ethnic Groups

Human narcolepsy-cataplexy, a sleep disorder associated with a centrally mediated hypocretin (orexin) deficiency, is tightly associated with HLA-DQB1*0602. Few studies have investigated the influence that additional HLA class II alleles have on susceptibility to this disease. In this work, 1,087 control subjects and 420 narcoleptic subjects with cataplexy, from three ethnic groups, were HLA typed, and the effects of HLA-DRB1, -DQA1, and -DQB1 were analyzed. As reported elsewhere, almost all narcoleptic subjects were positive for both HLA-DQA1*0102 and -DQB1*0602. A strong predisposing effect was observed in DQB1*0602 homozygotes, across all ethnic groups. Relative risks for narcolepsy were next calculated for heterozygous DQB1*0602/other HLA class II allelic combinations. Nine HLA class II alleles carried in trans with DQB1*0602 were found to influence disease predisposition. Significantly higher relative risks were observed for heterozygote combinations including DQB1*0301, DQA1*06, DRB1*04, DRB1*08, DRB1*11, and DRB1*12. Three alleles-DQB1*0601, DQB1*0501, and DQA1*01 (non-DQA1*0102)-were found to be protective. The genetic contribution of HLA-DQ to narcolepsy susceptibility was also estimated by use of lambda statistics. Results indicate that complex HLA-DR and -DQ interactions contribute to the genetic predisposition to human narcolepsy but that additional susceptibility loci are also most likely involved. Together with the recent hypocretin discoveries, these findings are consistent with an immunologically mediated destruction of hypocretin-containing cells in human narcolepsy-cataplexy.

Epigenetic aberration of the human REELIN gene in psychiatric disorders.

Epigenetic genome modifications such as DNA methylation appear to be involved in various diseases. Here, we suggest that the levels of DNA methylation at the BssHII methylation-sensitive restriction enzyme sites in the human REELIN (RELN) gene in the forebrain vary among individuals. Interestingly, although a statistically significant correlation between the levels of DNA methylation in RELN and age was detected in healthy individuals, no such correlations were seen in either schizophrenic or bipolar patients. In addition, reverse correlations between DNA methylation levels and RELN expression were also detected in postmortem brain RNA and on in vitro assay. These data suggest the possibility that epigenetic aberration from the normal DNA methylation status of RELN may confer susceptibility to psychiatric disorders.

Allele-specific binding of the ubiquitous transcription factor OCT-1 to the functional single nucleotide polymorphism (SNP) sites in the tumor necrosis factor-alpha gene (TNFA) promoter.

The tumor necrosis factor-alpha gene (TNFA) is characterized by several single nucleotide polymorphisms (SNPs) in its promoter region. Interestingly, some of these SNPs appear to influence TNFA expression and susceptibility to various human diseases, but the molecular mechanisms by which such possibly functional SNPs modulate TNFA expression are poorly understood. In this study, we show allele-specific binding of the ubiquitous transcription factor OCT-1 to the SNP sites at positions −863 and −857 in the promoter, which appear to affect TNFA expression: the protein was associated with variant allele possessing either −863A or −857T, but rarely with the common allele (−863C and −857C). The evidence presented here, therefore, suggests the possibility that OCT-1 could contribute to the modulation of TNFA expression by means of its allele-specific binding manner.

Genomewide Association Analysis of Human Narcolepsy and a New Resistance Gene

Human narcolepsy is a hypersomnia that is affected by multiple genetic and environmental factors. One genetic factor strongly associated with narcolepsy is the HLA-DRB1*1501-DQB1*0602 haplotype in the human leukocyte antigen region on chromosome 6, whereas the other genetic factors are not clear. To discover additional candidate regions for susceptibility or resistance to human narcolepsy, we performed a genomewide association study, using 23,244 microsatellite markers. Two rounds of screening with the use of pooled DNAs yielded 96 microsatellite markers (including 16 markers on chromosome 6) with significantly different estimated frequencies in case and control pools. Markers not located on chromosome 6 were evaluated by the individual typing of 95 cases and 95 controls; 30 markers still showed significant associations. A strong association was displayed by a marker on chromosome 21 (21q22.3). The surrounding region was subjected to high-density association mapping with 14 additional microsatellite markers and 74 SNPs. One microsatellite marker (D21S0012m) and two SNPs (rs13048981 and rs13046884) showed strong associations (P < .0005; odds ratios 0.19-0.33). These polymorphisms were in a strong linkage disequilibrium, and no other polymorphism in the region showed a stronger association with narcolepsy. The region contains three predicted genes--NLC1-A, NLC1-B, and NLC1-C--tentatively named narcolepsy candidate-region 1 genes, and NLC1-A and NLC1-C were expressed in human hypothalamus. Reporter-gene assays showed that the marker D21S0012m in the promoter region and the SNP rs13046884 in the intron of NLC1-A significantly affected expression levels. Therefore, NLC1-A is considered to be a new resistance gene for human narcolepsy.

Predisposing factors in delayed sleep phase syndrome.

We classified 64 patients with chronic delayed sleep phase syndrome (DSPS) into the primary (n = 53) and secondary (n = 11) group according to presence or absence of such signs as difficulty in waking up which appeared much earlier than the onset of DSPS. The age at the onset of the early signs concentrated in adolescence. The familial occurrence of DSPS was noted in 11 patients of the primary group. In human leukocyte antigen (HLA) typing, the incidence of DR1 positivity alone was significantly higher in DSPS patients than in healthy subjects. Minnesota Multiphasic Personality Inventory revealed high scores on depression, psychoasthenia and hypochondriasis. We suggest that a predisposition to DSPS includes biological, genetic, social and psychological factors, various combinations of which may lead to DSPS.

Profiling of genes expressed in human monocytes and monocyte-derived dendritic cells using cDNA expression array

Using a human cDNA expression array, we obtained expression profiles of 588 genes in CD14+ monocytes and monocyte‐derived dendritic cells (DCs). Overall, 22 genes were upregulated, and nine genes were downregulated in DCs of both samples from two different individuals. Many of the genes that were upregulated in DCs encode proteins that are related to differentiation, cell structure, migration, termination of cell cycle as well as proliferation, e.g. tumour necrosis factor‐α (TNF‐α), tumour necrosis factor receptor II (TNFRII), thymosin β‐10, epithelial discoidin domain receptor 1, replication factor C, putative transcription factor DB1, alpha catenin, transforming growth factor‐β1, prohibitin, p53‐regulating protein and neu differentiation factor. Among the downregulated genes in DCs were genes that encode proteins of cell cycle regulation: mitotic growth and transcription activator, platelet‐derived growth factor receptor‐β subunit, interleukin 2 receptor (IL‐2R)‐γ subunit, IL‐7R‐α subunit, leucocyte interferon‐γ (IFN‐γ) and granulocyte–macrophage colony‐stimulating factor receptor (GM‐CSFR). Semi‐quantitative reverse transcription–polymerase chain reaction method confirmed the upregulated expression levels in DCs for TNFRII, TNF‐α, alpha catenin and downregulation of IFN‐γ, GM‐CSFR on four different donor samples of DCs and monocytes. Moreover, our data show the presence of a ‘switch‐on’ step for the TNF‐α and TNFRII gene expression in immature DCs for further differentiation into mature DCs.

Possible association of human leucocyte antigen DR1 with delayed sleep phase syndrome

The study investigated the human leucocyte antigen (HLA), types A, B and DR, of 42 patients with delayed sleep phase syndrome (DSPS) and compared the frequencies of the antigens with those in 117 healthy controls. The comparison revealed that the gene frequencies and positivities of HLA‐A, ‐B and ‐DR, except for DR1, had no significant differences between the patients and controls. The frequency of HLA‐DR1 was increased in the DSPS patients as compared with that in the healthy controls (P = 0.0069 in positivity). Although the corrected P‐value (0.069) for multiple comparisons almost reached the significance level, the results indicated a possible association of the HLA‐DR1 antigen with DSPS. This study suggests that there are genetic predispositions to DSPS.

Support for an association between HLA-DR1 and schizophrenia in the Japanese population

An increase of HLA-DR1 has been observed in schizophrenia patients from the Japanese population. A decrease of DR4, which was reported in Caucasian patients, has also been found in some of the Japanese studies. This small study further investigated frequencies of HLA-DR1 and DR4 in unrelated Japanese patients with schizophrenia (n = 45) and healthy comparison subjects (n = 117). The number of patients possessing DR1 was higher (10 of 45, 22%) compared with the comparison group (11 of 117, 9.4%, P = 0.03). This may support the previous observation of an increased DR1 frequency in the Japanese patients. When the present data is combined with three previous studies, proportions of the Japanese subjects with DR1 were 98 of 588 schizophrenia patients (16.7%) vs. 93 of 942 comparison subjects (9.9%). However, no difference was observed in DR4 frequencies between the patients (51%) and comparison subjects (44%). Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:725-727, 2000.

The possible association between epigenetic aberration in DNA methylation in RELN and psychiatric disorders

The possible association between epigenetic aberration in DNA methylation in RELN and psychiatric disorders

MHC (major histocompatibility complex)-DRB genes and polymorphisms in common marmoset.

Abstract. A New World monkey, the common marmoset (Callithrix jacchus), will be used as a preclinical animal model to study the feasibility of cell and gene therapy targeting immunological and hematological disorders. For elucidating the immunogenetic background of common marmoset to further studies, in the present study, polymorphisms of MHC-DRB genes in this species were examined. Twenty-one Caja-DRB exon 2 alleles, including seven new ones, were detected by means of subcloning and the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) methods followed by nucleotide sequencing. Based on the alignment of these allele sequences, we designed two pairs of specific primers and established a PCR-SSCP method for DNA-based histocompatibility typing of the common marmoset. According to the family segregation data and phylogenetic analyses, we presumed that Caja-DRB alleles could be classified into five different loci. Southern blotting analysis also supported the existence of multiple DRB loci. The patterns of nucleotide substitutions suggests that positive selection operates in the antigen-recognition sites of Caja-DRB genes.