Norio Matsuura

Identification of RNF213 as a Susceptibility Gene for Moyamoya Disease and Its Possible Role in Vascular Development

Background Moyamoya disease is an idiopathic vascular disorder of intracranial arteries. Its susceptibility locus has been mapped to 17q25.3 in Japanese families, but the susceptibility gene is unknown. Methodology/Principal Findings Genome-wide linkage analysis in eight three-generation families with moyamoya disease revealed linkage to 17q25.3 (P<10-4). Fine mapping demonstrated a 1.5-Mb disease locus bounded by D17S1806 and rs2280147. We conducted exome analysis of the eight index cases in these families, with results filtered through Ng criteria. There was a variant of p.N321S in PCMTD1 and p.R4810K in RNF213 in the 1.5-Mb locus of the eight index cases. The p.N321S variant in PCMTD1 could not be confirmed by the Sanger method. Sequencing RNF213 in 42 index cases confirmed p.R4810K and revealed it to be the only unregistered variant. Genotyping 39 SNPs around RNF213 revealed a founder haplotype transmitted in 42 families. Sequencing the 260-kb region covering the founder haplotype in one index case did not show any coding variants except p.R4810K. A case-control study demonstrated strong association of p.R4810K with moyamoya disease in East Asian populations (251 cases and 707 controls) with an odds ratio of 111.8 (P = 10−119). Sequencing of RNF213 in East Asian cases revealed additional novel variants: p.D4863N, p.E4950D, p.A5021V, p.D5160E, and p.E5176G. Among Caucasian cases, variants p.N3962D, p.D4013N, p.R4062Q and p.P4608S were identified. RNF213 encodes a 591-kDa cytosolic protein that possesses two functional domains: a Walker motif and a RING finger domain. These exhibit ATPase and ubiquitin ligase activities. Although the mutant alleles (p.R4810K or p.D4013N in the RING domain) did not affect transcription levels or ubiquitination activity, knockdown of RNF213 in zebrafish caused irregular wall formation in trunk arteries and abnormal sprouting vessels. Conclusions/Significance We provide evidence suggesting, for the first time, the involvement of RNF213 in genetic susceptibility to moyamoya disease.

Mutations in SLC6A19 , encoding B 0 AT1, cause Hartnup disorder

Hartnup disorder, an autosomal recessive defect named after an English family described in 1956 (ref. 1), results from impaired transport of neutral amino acids across epithelial cells in renal proximal tubules and intestinal mucosa. Symptoms include transient manifestations of pellagra (rashes), cerebellar ataxia and psychosis. Using homozygosity mapping in the original family in whom Hartnup disorder was discovered, we confirmed that the critical region for one causative gene was located on chromosome 5p15 (ref. 3). This region is homologous to the area of mouse chromosome 13 that encodes the sodium-dependent amino acid transporter B0AT1 (ref. 4). We isolated the human homolog of B0AT1, called SLC6A19, and determined its size and molecular organization. We then identified mutations in SLC6A19 in members of the original family in whom Hartnup disorder was discovered and of three Japanese families. The protein product of SLC6A19, the Hartnup transporter, is expressed primarily in intestine and renal proximal tubule and functions as a neutral amino acid transporter.

Autosomal dominant moyamoya disease maps to chromosome 17q25.3.

Background: Moyamoya disease (MMD) is an idiopathic steno-occlusive cerebrovascular disease that represents an important cause of stroke. However, etiology of the disease has remained largely unknown. Methods: We previously showed that the inheritance pattern of MMD is autosomal dominant with incomplete penetrance. Here, we report the genome-wide parametric linkage analysis for MMD in 15 extended Japanese families. We conducted linkage analyses under two diagnostic classifications: narrow and broad. Affected member-only analysis was applied due to incomplete and age-dependent penetrance of the disease. Results: Under both classifications, significant evidence of linkage was only observed on chromosome 17q25.3, with maximum multipoint logarithm of odds (lod) scores of 6.57 (under the narrow classification) and 8.07 (under the broad classification) at D17S704. Haplotype analysis revealed segregation of a disease haplotype in all families but one, and informative crossovers enabled mapping of the MMD locus to a 3.5-Mb region between D17S1806 and the telomere of 17q, encompassing 94 annotated genes. Conclusions: Our data suggest that there is a major gene locus for autosomal dominant moyamoya disease on chromosome 17q25.3.

Confirmation of an Association of Single-Nucleotide Polymorphism rs1333040 on 9p21 With Familial and Sporadic Intracranial Aneurysms in Japanese Patients

Background and Purpose— Genetic factors are important determinants of intracranial aneurysm (IA). Recently, a multinational, genome-wide association study identified 3 loci associated with IA, located on 2q (rs700651), 8q (rs10958409), and 9p (rs1333040 and rs10757278). The aim of this study was to evaluate these associations. Methods— Familial and sporadic cases were investigated. Familial cases, consisting of 96 subjects with IA, and 46 subjects of unknown status from 31 pedigrees were analyzed with the transmission disequilibrium test and linkage analysis. Associations of single-nucleotide polymorphisms (SNPs) with IA were tested in 419 sporadic IA cases and in 408 control subjects. Sequencing of CDKN2A, CDKN2B, and CDKN2BAS revealed additional SNPs, and their associations with IA were also tested. Results— The transmission disequilibrium test revealed associations of 2 SNPs, rs700651 (P=0.036) and rs1333040 (P=0.002), with familial IA. Analysis of SNPs in sporadic cases revealed an allelic association of rs1333040 with IA (odds ratio=1.28; 95% CI, 1.04–1.57; P=0.02) but failed to show associations of rs10757278 and rs496892 with IA. We sequenced 3 candidate genes; CDKN2A, CDKN2B, and CDKN2BAS. All 6 index cases from IA families had the rs1333040-T allele and SNPs (rs10965215, rs10120688, and rs7341791) in CDKN2BAS. None of these SNPs had linkage disequilibrium with rs1333040 and was associated with IA. Conclusions— A region between introns 7 and 15 of CDKN2BAS carrying the rs1333040-T allele may confer risk for IA.

Identification of MMP1 as a novel risk factor for intracranial aneurysms in ADPKD using iPSC models

Cardiovascular complications are the leading cause of death in autosomal dominant polycystic kidney disease (ADPKD), and intracranial aneurysm (ICA) causing subarachnoid hemorrhage is among the most serious complications. The diagnostic and therapeutic strategies for ICAs in ADPKD have not been fully established. We here generated induced pluripotent stem cells (iPSCs) from seven ADPKD patients, including four with ICAs. The vascular cells differentiated from ADPKD-iPSCs showed altered Ca2+ entry and gene expression profiles compared with those of iPSCs from non-ADPKD subjects. We found that the expression level of a metalloenzyme gene, matrix metalloproteinase (MMP) 1, was specifically elevated in iPSC-derived endothelia from ADPKD patients with ICAs. Furthermore, we confirmed the correlation between the serum MMP1 levels and the development of ICAs in 354 ADPKD patients, indicating that high serum MMP1 levels may be a novel risk factor. These results suggest that cellular disease models with ADPKD-specific iPSCs can be used to study the disease mechanisms and to identify novel disease-related molecules or risk factors.

Evaluation of a mass screening program for lysinuric protein intolerance in the northern part of Japan.

Lysinuric protein intolerance (LPI:MIM 222700) is an autosomal recessive disease characterized by defective transport of the dibasic amino acids. We recently reported a local cluster of LPI in the northern part of Japan (Koizumi et al., 2000). Mutational analysis of the LPI patients in this local cluster revealed they were exclusively homozygous for the R410X mutation. The effectiveness of early intervention with citrulline therapy (200 mg/kg per day) and protein restriction (1.5 g/kg per day) was confirmed in these patients. Mass screening was conducted in 4,568 newborn babies between 1999 and 2002, which was estimated to cover 100% of almost all newborns delivered in the screened area. Forty heterozygous newborns were found (0.88%), leading to an estimated incidence of LPI of 1:51,984. The number of people that required screening to detect one case was 51,984, and the cost for mass screening was 30 cents/person (a total of dollars 15,600). This is comparable to, or even less than, the cost of currently screened diseases in Japan. Therefore, we conclude that a mass screening program for LPI can be introduced effectively and economically into an area where an LPI cluster is located as the result of a founder mutation.

Importance of molecular diagnosis in the accurate diagnosis of systemic carnitine deficiency

1Department of Health and Environmental Sciences, Kyoto University Graduate School of Medicine, Yoshida Konoecho, Kyoto 606-8501, Japan 2Faculty of Medical Sciences, Department of Health Science, University of Fukui, Fukui 910-1193, Japan 3Department of Genetics, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya 663-8501, Japan 4Ishikawa Prefectural Central Hospital, Kuratsukihigashi, Kanazawa, Ishikawa 920-8530, Japan 5Department of Pediatrics (NICU), Kyoto University Hospital, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan