Yasuyuki Fukumaki

Accelerated evolution of crotalinae snake venom gland serine proteases

Eight cDNAs encoding serine proteases isolated from Trimeresurus flavoviridis (habu snake) and T. gramineus (green habu snake) venom gland cDNA libraries showed that nonsynonymous nucleotide substitutions have accumulated in the mature protein‐coding regions to cause amino acid changes. Southern blot analysis of T. flavoviridis genomic DNAs using two proper probes indicated that venom gland serine protease genes form a multigene family in the genome. These observations suggest that venom gland serine proteases have diversified their amino acid sequences in an accelerating manner. Since a similar feature has been previously discovered in crotalinae snake venom gland phospholipase A2 (PLA2) isozyme genes, accelerated evolution appears to be universal in plural isozyme families of crotalinae snake venom gland.

Positive associations of polymorphisms in the metabotropic glutamate receptor type 3 gene (GRM3) with schizophrenia

Objectives Glutamatergic dysfunction is one of the major hypotheses of schizophrenia pathophysiology. We have been conducting systematic studies on the association between glutamate receptors and schizophrenia. We focused on the metabotropic glutamate receptor type 3 gene (GRM3) as a candidate for schizophrenia susceptibility. Methods We genotyped Japanese schizophrenics (n = 100) and controls (n = 100) for six single nucleotide polymorphisms (SNPs) located in the GRM3 region at intervals of approximately 50 kb. Statistical differences in genotype, allele and haplotype frequencies between cases and controls were evaluated by the &KHgr;2 test and Fishers exact probability test at a significance level of 0.05. Haplotype frequencies were estimated by the EM algorithm. Results A case‐control association study identified a significant difference in allele frequency distribution of a SNP, rs1468412, between schizophrenics and controls (P=0.011). We also observed significant differences in haplotype frequencies estimated from SNP frequencies between schizophrenics and controls. The haplotype constructed from three SNPs, including rs1468412, showed a significant association with schizophrenia (P=8.30 × 10−4). Conclusions Our data indicate that at least one susceptibility locus for schizophrenia is situated within or very close to the GRM3 region in the Japanese patients.

Heterozygous deletion of ITPR1, but not SUMF1 in spinocerebellar ataxia type 16

We have previously mapped autosomal dominant spinocerebellar ataxia (SCA) 16 to 3p26, overlapping with the locus of SCA15. Recently, partial deletions of ITPR1 and the neighbouring SUMF1 in the SCA15 and two additional families were reported. In the present study we determined the copy number of these genes by real time quantitative polymerase chain reaction (PCR) and found a heterozygous deletion of exons 1-48 of ITPR1, but not SUMF1 in SCA16. Breakpoint analysis revealed that the size of the deletion is 313,318 bp and the telomeric breakpoint is located in the middle of their intergenic region. Our data provide evidence that haploinsufficiency of ITPR1 alone causes SCA16 and SCA15.

Genomewide High-Density SNP Linkage Analysis of 236 Japanese Families Supports the Existence of Schizophrenia Susceptibility Loci on Chromosomes 1p, 14q, and 20p

The Japanese Schizophrenia Sib-Pair Linkage Group (JSSLG) is a multisite collaborative study group that was organized to create a national resource for affected sib pair (ASP) studies of schizophrenia in Japan. We used a high-density single-nucleotide-polymorphism (SNP) genotyping assay, the Illumina BeadArray linkage mapping panel (version 4) comprising 5,861 SNPs, to perform a genomewide linkage analysis of JSSLG samples comprising 236 Japanese families with 268 nonindependent ASPs with schizophrenia. All subjects were Japanese. Among these families, 122 families comprised the same subjects analyzed with short tandem repeat markers. All the probands and their siblings, with the exception of seven siblings with schizoaffective disorder, had schizophrenia. After excluding SNPs with high linkage disequilibrium, we found significant evidence of linkage of schizophrenia to chromosome 1p21.2-1p13.2 (LOD=3.39) and suggestive evidence of linkage to 14q11.2 (LOD=2.87), 14q11.2-q13.2 (LOD=2.33), and 20p12.1-p11.2 (LOD=2.33). Although linkage to these regions has received little attention, these regions are included in or partially overlap the 10 regions reported by Lewis et al. that passed the two aggregate criteria of a meta-analysis. Results of the present study--which, to our knowledge, is the first genomewide analysis of schizophrenia in ASPs of a single Asian ethnicity that is comparable to the analyses done of ASPs of European descent--indicate the existence of schizophrenia susceptibility loci that are common to different ethnic groups but that likely have different ethnicity-specific effects.

Severity differences in β‐thalassaemia/haemoglobin E syndromes: implication of genetic factors

Summary. Genetic factors determining the difference in severity of anaemia in β‐thalassaemia/HbE disease were studied in 90 patients who had haemoglobin levels, at steady state, ranging from 4.2 to 12.6 g/dl. Co‐inheritance of α‐thalassaemia 2 and haemoglobin Constant Spring could significantly decrease the severity of the disease. Inheritance of a β‐thalassaemia chromosome with Xmn I cleavage site at position — 158 of the Gγ‐globin gene which was linked to the haplotype ‐ + ‐ ++ or ++ ‐ ++, was associated with a milder anaemia. Two copies of these alleles were necessary to produce a significant clinical effect. Increased expression of the Gγ‐globin gene and higher production of haemoglobin F. which could reduce the overall globin chain imbalance, were also associated with homozygosity for the Xmn I cleavage site and thus with less severe anaemia. However, this effect was not seen in Xmn I site heterozygotes. Whether the effects of the Xmn I polymorphism, HbF concentration and Gγ/Aγ ratio act separately or through common mechanisms in reducing anaemia remains to be ascertained.

Association analysis of polymorphisms in the upstream region of the human dopamine D4 receptor gene (DRD4) with schizophrenia and personality traits.

AbstractThe human dopamine D4 receptor (DRD4) is of major interest in molecular studies of schizophrenia and personality traits. We examined the association of schizophrenia and polymorphisms in the upstream region of the DRD4 gene (−768G>A in the negative modulator region; −521C>T, −376C>T, and −291C>T in the cell type-specific promoter region; and −616C>G between the two regions) in 208 schizophrenic patients and 210 normal controls. No significant difference in genotype and allele frequencies was observed between the two groups, indicating that these polymorphisms do not make a major contribution to the pathogenesis of schizophrenia. We also studied the association of polymorphisms in the upstream region and a 48-bp repeat polymorphism in exon III of the DRD4 gene with personality traits in 173 Japanese individuals who completed the temperament and character inventory (TCI). The −768G>A polymorphism was significantly associated with reward dependence (P = 0.044), while no significant association was observed between novelty seeking and polymorphisms in the upstream region or the exon III repeat polymorphism of the DRD4 gene.

Molecular basis of β-thalassemia in Thailand: analysis of β-thalassemia mutations using the polymerase chain reaction

Summaryβ-Thalassemia mutations in 71 chromosomes of Thai patients from the northeast, the middle and the south of the country were investigated using dot blot hybridization of PCR (polymerase chain reaction)-amplified DNA with allelespecific oligonucleotide probes. Eight different known molecular defects were detected, at different frequencies. There was an amber mutation in codon 17, a C-T transversion at position 654 of IVS-2, a frameshift mutation between codons 71 and 72, an A-G transition at nucleotide -28 within the TATA box (known as Chinese mutations), a G-T transversion at position 1 of IVS-1 (an Indian mutation), a 4bp deletion in codons 41/42 and a G-C transversion at position 5 of IVS-1 (described as both Chinese and Indian mutations) and a Thai original mutation, an ochre mutation in codon 35. Analysis of the three unknown alleles by DNA sequencing of the cloned DNA fragment amplified by PCR revealed an A-G substitution at the second position of the codon for amino acid 19 (AAC-AGC). The analytic approach used in the present study and the characteristic distribution of mutations in each region of Thailand will prove useful for setting up a prenatal diagnosis program.

A unique case of fibrodysplasia ossificans progressiva with an ACVR1 mutation, G356D, other than the common mutation (R206H).

Fibrodysplasia ossificans progressiva (FOP) is a rare autosomal dominant congenital disease characterized by progressive heterotopic endochondral osteogenesis with great‐toe malformations. A 617G > A (R206H) mutation of the activin A type 1 receptor gene (ACVR1) has been found in all previously reported patients with FOP. Thus, this is one of the most specific of all disease‐associated mutations. We report here on a 62‐year‐old man with slowly progressive FOP and a novel mutation in ACVR1. He developed difficulty in moving his shoulder since age 10 years due to contraction of the shoulder joint. The symptoms progressed slowly, and he could not walk at age 36 years and was bedridden at 55 years. He also showed rigid spine, baldness, sensorineural hearing loss, and hypodactyly accompanied by abnormal ectopic ossification. Analysis of ACVR1 and its cDNA revealed that the patient is heterozygous for a mutation, 1067G > A (G356D). Typing of SNPs located in the ∼0.5‐Mb region spanning ACVR1 and its neighbor genes suggested that 1067G > A is a de novo mutation. These results give a clue to better understanding of FOP as well as of the mild clinical symptoms in the patient.

Accelerated evolution of Trimeresurus okinavensis venom gland phospholipase A2 isozyme-encoding genes.

Three Trimeresurus okinavensis (To; himehabu snake, Crotalinae) venom gland phospholipase A2 (PLA2) isozymeencoding genes, gPLA2-o1, gPLA2-o2 and gPLA2-o3, were isolated from its genomic DNA library. The nucleotide (nt) sequence analysis revealed that two of the three genes (gPLA2-o2 and gPLA2-o3) occasionally have been converted to inactivated genes by introduction of one base insertion or substitution. It was confirmed from Southern blot analysis that the To haploid genome contains only three venom gland PLA2 isozyme genes herein isolated. Comparison of these genes showed that nonsynonymous nt substitutions have occurred more frequently than synonymous nt substitutions in the protein-coding regions, except for the signal-peptide coding domain, implying that To venom gland PLA2 isozyme genes have evolved via accelerated evolution. Such an evolutionary feature of To venom gland PLA2 isozyme genes proves the general universality of accelerated evolution previously drawn for venom gland PLA2 isozyme genes of other crotalinae snakes. The variability in the mature protein-coding regions of three To venom gland PLA2 isozyme genes appears to have been brought about by natural selection for point mutations.

Positive associations of polymorphisms in the metabotropic glutamate receptor type 8 gene (GRM8) with schizophrenia

The glutamatergic dysfunction has been implicated in pathophysiology of schizophrenia. The Group III metabotropic glutamate receptor 4 (mGluR4), 6, 7, and 8 are thought to modulate glutamatergic transmission in the brain by inhibiting glutamate release at the synapse. We tested association of schizophrenia with GRM8 using 22 single nucleofide polymorphisms (SNPs) with the average intervals of 40.3 kb in the GRM8 region in 100 case‐control pairs for the SNPs. Although we observed significant associations of schizophrenia with two SNPs, SNP18 (rs2237748, allele: P = 0.0279; genotype: P = 0.0124) and SNP19 (rs2299472, allele: P = 0.0302; genotype: P = 0.0127), none of two SNPs showed significant association with disease after Bonferroni correction. Both SNP18 and SNP19 were included in a large region (>330 kb) in which SNPs are in linkage disequilibrium (LD) at the 3′ region of GRM8. We also tested haplotype association of schizophrenia with constructed haplotypes of the SNPs in LD. Significant associations were detected for the combinations of SNP5‐SNP6 (χ2 = 18.12, df = 3, P = 0.0004, P corr = 0.0924 with Bonferroni correction), SNP4‐SNP5‐SNP6 (χ2 = 27.50, df = 7, P = 0.0075, P corr = 0.015 with Bonferroni correction), and SNP5‐SNP6‐SNP7 (χ2 = 23.92, df = 7, P = 0.0011, P corr = 0.0022 with Bonferroni correction). Thus, we conclude that at least one susceptibility locus for schizophrenia is located within the GRM8 region in Japanese.