Moyamoya disease (MMD) shows progressive cerebral angiopathy characterized by bilateral internal carotid artery stenosis and abnormal collateral vessels. Although B15% of MMD cases are familial, the MMD gene(s) remain unknown. A genome-wide association study of 785 720 single-nucleotide polymorphisms (SNPs) was performed, comparing 72 Japanese MMD patients with 45 Japanese controls and resulting in a strong association of chromosome 17q25-ter with MMD risk. This result was further confirmed by a locus-specific association study using 335 SNPs in the 17q25-ter region. A single haplotype consisting of seven SNPs at the RNF213 locus was tightly associated with MMD (P¼5.3Â10 À10 ). RNF213 encodes a really interesting new gene finger protein with an AAA ATPase domain and is abundantly expressed in spleen and leukocytes. An RNA in situ hybridization analysis of mouse tissues indicated that mature lymphocytes express higher levels of Rnf213 mRNA than their immature counterparts. Mutational analysis of RNF213 revealed a founder mutation, p.R4859K, in 95% of MMD families, 73% of non-familial MMD cases and 1.4% of controls; this mutation greatly increases the risk of MMD (P¼1.2Â10 À43 , odds ratio¼190.8, 95% confidence interval¼71.7-507.9). Three additional missense mutations were identified in the p.R4859K-negative patients. These results indicate that RNF213 is the first identified susceptibility gene for MMD.

The role of monogenic mutations in the development of 46,XX testicular/ovotesticular disorders of sex development (DSD) remains speculative. Although mutations in NR5A1 are known to cause 46,XY gonadal dysgenesis and 46,XX ovarian insufficiency, such mutations have not been implicated in testicular development of 46,XX gonads. Here, we identified identical NR5A1 mutations in two unrelated Japanese patients with 46,XX testicular/ovotesticular DSD. The p.Arg92Trp mutation was absent from the clinically normal mothers and from 200 unaffected Japanese individuals. In silico analyses scored p.Arg92Trp as probably pathogenic. In vitro assays demonstrated that compared with wild-type NR5A1, the mutant protein was less sensitive to NR0B1-induced suppression on the SOX9 enhancer element. Other sequence variants found in the patients were unlikely to be associated with the phenotype. The results raise the possibility that specific mutations in NR5A1 underlie testicular development in genetic females.

Autosomal-dominant, nonsyndromic hearing impairment is clinically and genetically heterogeneous. We encountered a large Japanese pedigree in which nonsyndromic hearing loss was inherited in an autosomal-dominant fashion. A genome-wide linkage study indicated linkage to the DFNA2 locus on chromosome 1p34. Mutational analysis of KCNQ4 encoding a potassium channel revealed a novel one-base deletion in exon 1, c.211delC, which generated a profoundly truncated protein without transmembrane domains (p.Q71fsX138). Previously, six missense mutations and one 13-base deletion, c.211_223del, had been reported in KCNQ4. Patients with the KCNQ4 missense mutations had younger-onset and more profound hearing loss than patients with the 211_223del mutation. In our current study, 12 individuals with the c.211delC mutation manifested late-onset and pure high-frequency hearing loss. Our results support the genotype-phenotype correlation that the KCNQ4 deletions are associated with later-onset and milder hearing impairment than the missense mutations. The phenotypic difference may be caused by the difference in pathogenic mechanisms: haploinsufficiency in deletions and dominant-negative effect in missense mutations.

Prospective treatment with this regimen can favorably modify the early neonatal course of severe NKH but does not prevent the poor long-term outcome, suggesting glycine-induced prenatal injury and/or ongoing postnatal damage.

Background: Non-ketotic hyperglycinaemia (NKH) is an inborn error of metabolism characterised by accumulation of glycine in body fluids and various neurological symptoms. NKH is caused by deficiency of the glycine cleavage multienzyme system with three specific components encoded by GLDC, AMT and GCSH. Most patients are deficient of the enzymatic activity of glycine decarboxylase, which is encoded by GLDC. Our recent study has suggested that there are a considerable number of GLDC mutations which are not identified by the standard exon-sequencing method. Methods: A screening system for GLDC deletions by multiplex ligation-dependent probe amplification (MLPA) has been developed. Two distinct cohorts of patients with typical NKH were screened by this method: the first cohort consisted of 45 families with no identified AMT or GCSH mutations, and the second cohort was comprised of 20 patients from the UK who were not prescreened for AMT mutations. Results: GLDC deletions were identified in 16 of 90 alleles (18%) in the first cohort and in 9 of 40 alleles (22.5%) in the second cohort. 14 different types of deletions of various lengths were identified, including one allele where all 25 exons were missing. Flanking sequences of interstitial deletions in five patients were determined, and Alu-mediated recombination was identified in three of five patients. Conclusions: GLDC deletions are a significant cause of NKH, and the MLPA analysis is a valuable first-line screening for NKH genetic testing.