Haruya Sakai

Homozygous c.14576G>A variant of RNF213 predicts early-onset and severe form of moyamoya disease

Objective: RNF213 was recently reported as a susceptibility gene for moyamoya disease (MMD). Our aim was to clarify the correlation between the RNF213 genotype and MMD phenotype. Methods: The entire coding region of the RNF213 gene was sequenced in 204 patients with MMD, and corresponding variants were checked in 62 pairs of parents, 13 mothers and 4 fathers of the patients, and 283 normal controls. Clinical information was collected. Genotype-phenotype correlations were statistically analyzed. Results: The c.14576G>A variant was identified in 95.1% of patients with familial MMD, 79.2% of patients with sporadic MMD, and 1.8% of controls, thus confirming its association with MMD, with an odds ratio of 259 and p < 0.001 for either heterozygotes or homozygotes. Homozygous c.14576G>A was observed in 15 patients but not in the controls and unaffected parents. The incidence rate for homozygotes was calculated to be >78%. Homozygotes had a significantly earlier age at onset compared with heterozygotes or wild types (median age at onset 3, 7, and 8 years, respectively). Of homozygotes, 60% were diagnosed with MMD before age 4, and all had infarctions as the first symptom. Infarctions at initial presentation and involvement of posterior cerebral arteries, both known as poor prognostic factors for MMD, were of significantly higher frequency in homozygotes than in heterozygotes and wild types. Variants other than c.14576G>A were not associated with clinical phenotypes. Conclusions: The homozygous c.14576G>A variant in RNF213 could be a good DNA biomarker for predicting the severe type of MMD, for which early medical/surgical intervention is recommended, and may provide a better monitoring and prevention strategy.

Species-specific distribution of heavy metals in tissues and organs of loggerhead turtle (Caretta caretta) and green turtle (Chelonia mydas) from Japanese coastal waters

Concentrations of heavy metals (Fe, Mn, Zn, Cu, Pb, Ni, Cd, Co and Hg) were determined in tissues and organs of loggerhead (Caretta caretta) and green turtles (Chelonia mydas) collected from Japanese coastal waters, in order to elucidate body distribution and to develop a non-lethal monitoring technique using the carapace. A majority of the metal burdens was present in the muscle, liver, bone and carapace of sea turtles. High Cu concentrations exceeding 10 μg/g wet wt were observed in the liver of these two turtle species. Mean Zn concentrations in fat tissues of loggerhead and green turtles were 94.6 and 51.3 μg/g wet wt respectively, which were about 10-fold higher than those reported in other marine animals. Concentrations of Mn, Zn and Hg in the carapace were correlated with whole body burdens, indicating that the carapace is a useful non-lethal indicator for monitoring heavy metal levels in the body of the sea turtle.

Heavy metal monitoring in sea turtles using eggs

Heavy metals in the muscles, livers, kidneys and eggs of loggerhead turtles and green sea turtles were analysed to develop a non-killing method of heavy metal monitoring using eggs. Heavy metal concentrations were higher in the liver and kidney than in the muscle and eggs of loggerhead turtles. Within an egg, yolk contained the highest concentrations and burdens of heavy metals. Heavy metal concentrations in egg yolks within the oviducts of a single loggerhead turtle were uniform without significant intra-oviduct variation. Similarly, there were no inter-clutch differences of an individual green turtle during one nesting season. Heavy metal concentrations in the yolk of eggs from the oviduct indicate the accumulation levels in female turtles, suggesting that the analysis in yolks of sea turtle eggs collected randomly from any clutch enable the estimation of the heavy metal concentrations in nesting female turtles, since there is less fluctuation of heavy metal concentrations in yolks of eggs laid by nesting loggerhead and green turtles.

Comprehensive genetic analysis of relevant four genes in 49 patients with Marfan syndrome or Marfan‐related phenotypes

In order to evaluate the contribution of FBN1, FBN2, TGFBR1, and TGFBR2 mutations to the Marfan syndrome (MFS) phenotype, the four genes were analyzed by direct sequencing in 49 patients with MFS or suspected MFS as a cohort study. A total of 27 FBN1 mutations (22 novel) in 27 patients (55%, 27/49), 1 novel TGFBR1 mutation in 1 (2%, 1/49), and 2 recurrent TGFBR2 mutations in 2 (4%, 2/49) were identified. No FBN2 mutation was found. Three patients with either TGFBR1 or TGFBR2 abnormality did not fulfill the Ghent criteria, but expressed some overlapping features of MFS and Loeys–Dietz syndrome (LDS). In the remaining 19 patients, either of the genes did not show any abnormalities. This study indicated that FBN1 mutations were predominant in MFS but TGFBRs defects may account for approximately 5–10% of patients with the syndrome.

Subcellular distribution of trace elements in the liver of sea turtles.

Subcellular distribution of Cu, Zn, Se, Rb, Mo, Ag, Cd and Pb was determined in the liver of green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) from Yaeyama Islands, Japan. Also, hepatic cytosol from sea turtles was applied on a Sephadex G-75 column and elution profiles of trace elements were examined. Copper, Zn, Se, Rb, Ag and Cd were largely present in cytosol in the liver of both species, indicating that cytosol was the significant site for the accumulation of these elements in sea turtles. In contrast, Mo and Pb were accumulated specifically in nuclear and mitochondrial fraction and microsomal fraction, respectively. Gel filtration analysis showed that Cu, Zn, Ag and Cd were bound to metallothionein (MT) in the cytosol of sea turtles. To our knowledge, this is the first report on the association of trace elements with MT in sea turtles.

Analysis of an insertion mutation in a cohort of 94 patients with spinocerebellar ataxia type 31 from Nagano, Japan

Spinocerebellar ataxia type 31 (SCA31) is a recently defined subtype of autosomal dominant cerebellar ataxia (ADCA) characterized by adult-onset, pure cerebellar ataxia. The C/T substitution in the 5′-untranslated region of the puratrophin-1 gene (PLEKHG4) or a disease-specific haplotype within the 900-kb SCA31 critical region just upstream of PLEKHG4 has been used for the diagnosis of SCA31. Very recently, a disease-specific insertion containing penta-nucleotide (TGGAA)n repeats has been found in this critical region in SCA31 patients. SCA31 was highly prevalent in Nagano, Japan, where SCA31 accounts for approximately 42% of ADCA families. We screened the insertion in 94 SCA31 patients from 71 families in Nagano. All patients had a 2.6- to 3.7-kb insertion. The size of the insertion was inversely correlated with the age at onset but not associated with the progression rate after onset. (TAGAA)n repeats at the 5′-end of the insertion were variable in number, ranging from 0 (without TAGAA sequence) to 4. The number of (TAGAA)n repeats was inversely correlated to the total size of the insertion. The number of (TAGAA)n repeats was comparatively uniform within patients from the three endemic foci in Nagano. Only one patient, heterozygous for the C/T substitution in PLEKHG4, had the insertions in both alleles; they were approximately 3.0 and 4.3 kb in size. Sequencing and Southern hybridization using biotin-labeled (TGGAA)5 probe strongly indicated that the 3.0-kb insertion, but not the 4.3-kb insertion, contained (TGGAA)n stretch. We also found that 3 of 405 control individuals (0.7%) had the insertions from 1.0 to 3.5 kb in length. They were negative for the C/T substitution in PLEKHG4, and neither of the insertions contained (TGGAA)n stretch at their 5′-end by sequencing. The insertions in normal controls were clearly detected by Southern hybridization using (TAAAA)5 probe, while they were not labeled with (TGGAA)5 or (TAGAA)5 probe. These data indicate that control alleles very rarely have a nonpathogenic large insertion in the SCA31 critical region and that not only the presence of the insertion but also its size is not sufficient evidence for a disease-causing allele. We approve of the view that (TGGAA)n repeats in the insertion are indeed related to the pathogenesis of SCA31, but it remains undetermined whether a large insertion lacking (TGGAA)n is nonpathogenic.

A -16C>T substitution in the 5' UTR of the puratrophin-1 gene is prevalent in autosomal dominant cerebellar ataxia in Nagano.

AbstractThe molecular bases of autosomal dominant cerebellar ataxia (ADCA) have been increasingly elucidated, but 17-50% of ADCA families still remain genetically undefined in Japan. In this study we investigated 67 genetically undefined ADCA families from the Nagano prefecture, and found that 63 patients from 51 families possessed the −16C>T change in the puratrophin-1 gene, which was recently found to be pathogenic for 16q22-linked ADCA. Most patients shared a common haplotype around the puratrophin-1 gene. All patients with the −16C>T change had pure cerebellar ataxia with middle-aged or later onset. Only one patient in a large, −16C>T positive family did not have this change, but still shared a narrowed haplotype with, and was clinically indistinguishable from, the other affected family members. In Nagano, 16q22-linked ADCA appears to be much more prevalent than either SCA6 or dentatorubral-pallidoluysian atrophy (DRPLA), and may explain the high frequency of spinocerebellar ataxia.

FBN2, FBN1, TGFBR1, and TGFBR2 analyses in congenital contractural arachnodactyly

FBN2, FBN1, TGFBR1, and TGFBR2 were analyzed by direct sequencing in 15 probands with suspected congenital contractural arachnodactyly (CCA). A total of four novel FBN2 mutations were found in four probands (27%, 4/15), but remaining the 11 did not show any abnormality in either of the genes. This study indicated that FBN2 mutations were major abnormality in CCA, and TGFBR and FBN1 defects may not be responsible for the disorder. FBN2 mutations were only found at introns 30, 31, and 35 in this study. Thus analysis of a mutational hotspot from exons 22 to 36 (a middle part) of FBN2 should be prioritized in CCA as previously suggested.

Rapid detection of gene mutations responsible for non-syndromic aortic aneurysm and dissection using two different methods: resequencing microarray technology and next-generation sequencing

Aortic aneurysm and/or dissection (AAD) is a life-threatening condition, and several syndromes are known to be related to AAD. In this study, two new technologies, resequencing array technology (ResAT) and next-generation sequencing (NGS), were used to analyze eight genes associated with syndromic AAD in 70 patients with non-syndromic AAD. Eighteen sequence variants were detected using both ResAT and NGS. In addition one of these sequence variants was detected by ResAT only and two additional variants by NGS only. Three of the 18 variants are likely to be pathogenic (in 4.3% of AAD patients and in 8.6% of a subset of patients with thoracic AAD), highlighting the importance of genetic analysis in non-syndromic AAD. ResAT and NGS similarly detected most, but not all, of the variants. Resequencing array technology was a rapid and efficient method for detecting most nucleotide substitutions, but was unable to detect short insertions/deletions, and it is impractical to update custom arrays frequently. Next-generation sequencing was able to detect almost all types of mutation, but requires improved informatics methods.

Craniosynostosis in a patient with a de novo 15q15-q22 deletion†

Interstitial deletions involving the chromosomal band 15q15 are very rare. A total of five cases were previously reported. Here another case of a 15q15.2‐q22.2 deletion is reported, presenting with severe craniosynostosis of coronary, metopic, and sagittal sutures. The chromosome 15 with the 17.7‐Mb deletion was of the paternal origin. A critical region for craniosynostosis may be located at the 734‐kb segment at 15q15.2. Interestingly, the entire FBN1 gene was deleted in this patient.