Mutations in Twinkle primase-helicase cause Perrault syndrome with neurologic features

OBJECTIVE

To identify the genetic cause in 2 families of progressive ataxia, axonal neuropathy, hyporeflexia, and abnormal eye movements, accompanied by progressive hearing loss and ovarian dysgenesis, with a clinical diagnosis of Perrault syndrome.

METHODS

Whole-exome sequencing was performed to identify causative mutations in the 2 affected sisters in each family. Family 1 is of Japanese ancestry, and family 2 is of European ancestry.

RESULTS

In family 1, affected individuals were compound heterozygous for chromosome 10 open reading frame 2 (C10orf2) p.Arg391His and p.Asn585Ser. In family 2, affected individuals were compound heterozygous for C10orf2 p.Trp441Gly and p.Val507Ile. C10orf2 encodes Twinkle, a primase-helicase essential for replication of mitochondrial DNA. Conservation and structural modeling support the causality of the mutations. Twinkle is known also to harbor multiple mutations, nearly all missenses, leading to dominant progressive external ophthalmoplegia type 3 and to recessive mitochondrial DNA depletion syndrome 7, also known as infantile-onset spinocerebellar ataxia.

CONCLUSIONS

Our study identifies Twinkle mutations as a cause of Perrault syndrome accompanied by neurologic features and expands the phenotypic spectrum of recessive disease caused by mutations in Twinkle. The phenotypic heterogeneity of conditions caused by Twinkle mutations and the genetic heterogeneity of Perrault syndrome call for genomic definition of these disorders.

Difference in disease-free survival curve and regional distribution according to subtype of spinocerebellar ataxia: a study of 1,286 Japanese patients

Expansions of trinucleotide repeats have been discovered in spinocerebellar ataxia (SCA) types 1, 2, 6, 7, 12, and 17, Machado-Joseph disease (MJD/SCA3), and dentatorubropallidoluysian atrophy (DRPLA). However, the frequency of familial SCA in Japan remains unclear. The number of trinucleotide repeats was determined for 1,286 patients. Three hundred and thirty families (523 cases) were autosomal dominant group (A), and 165 families were positive for family history but not autosomal dominant group (B), while the remaining 598 cases were the sporadic group (C). The frequency of SCA subtypes in autosomal dominant group was: 1) 5.5% for SCA1; 2) 2.4% for SCA2; 3) 27.6% for MJD/SCA3; 4) 25.5% for SCA6; 5) 0.3% for SCA17; and 6) 7.3% for DRPLA. Abnormal expansion of SCA12 was not detected. Another 31.5% of the patients in the autosomal dominant group had unknown genetic abnormalities. Within group B, SCA6 was the most prominent and within the sporadic group MJD/SCA3 and SCA6 were the most common subtypes observed. The disease-free survival curve of SCA6 was different from that of other SCAs and the mean age at onset for SCA6 was found to be later than that of the other types. Regional differences were observed in the relative rate of SCA subtypes. MJD/SCA3 appears more common in the Kanto and Kyushu districts of Japan, whereas SCA6 is most common in the Chugoku district. In order to establish an effective social welfare system for SCA patients, clinical course and regional differences in the prevalence of SCA subtypes must be taken into consideration.

A mutation in the low voltage-gated calcium channel CACNA1G alters the physiological properties of the channel, causing spinocerebellar ataxia

BACKGROUND

Spinocerebellar ataxia (SCA) is a genetically heterogeneous disease. To date, 36 dominantly inherited loci have been reported, and 31 causative genes have been identified.

RESULTS

In this study, we analyzed a Japanese family with autosomal dominant SCA using linkage analysis and exome sequencing, and identified CACNA1G, which encodes the calcium channel CaV3.1, as a new causative gene. The same mutation was also found in another family with SCA. Although most patients exhibited the pure form of cerebellar ataxia, two patients showed prominent resting tremor in addition to ataxia. CaV3.1 is classified as a low-threshold voltage-dependent calcium channel (T-type) and is expressed abundantly in the central nervous system, including the cerebellum. The mutation p.Arg1715His, identified in this study, was found to be located at S4 of repeat IV, the voltage sensor of the CaV3.1. Electrophysiological analyses revealed that the membrane potential dependency of the mutant CaV3.1 transfected into HEK293T cells shifted toward a positive potential. We established induced pluripotent stem cells (iPSCs) from fibroblasts of the patient, and to our knowledge, this is the first report of successful differentiation from the patient-derived iPSCs into Purkinje cells. There was no significant difference in the differentiation status between control- and patient-derived iPSCs.

CONCLUSIONS

To date, several channel genes have been reported as causative genes for SCA. Our findings provide important insights into the pathogenesis of SCA as a channelopathy.

Intraoperative pleural lavage cytology in lung cancer patients

Cytology of intraoperative pleural lavage was examined in 164 lung cancer patients who underwent pulmonary resections. None of the patients had any pleural effusion or dissemination. Cytology was performed three times: (1) at thoracotomy, (2) immediately after resection, and (3) after washing the pleural cavity with 5,000 mL of physiological saline solution just before closure of the chest wall. Twenty-three patients (14%) had more than one positive cytological finding. The frequency of positive cytological findings was significantly correlated with pathological T classification, pleural status, and pathological stage. The positive lavage group had a significantly higher recurrence rate than the negative lavage group in patients with stage I or stage II cancer. Four patients in the positive lavage group (17.4%) had recurrence in pleura or pericardium whereas only 1 patient in the negative lavage group (0.7%) had a recurrence in pericardium. The positive cytological finding of pleural lavage has more important meaning as a prognostic factor in stage I and stage II and indicates a greater possibility of recurrence in pleura or pericardium, but further examinations to evaluate the viability of detected malignant cells are required so that the positive cytological findings of pleural lavage can be regarded as subclinical pleural dissemination.

SCA8 repeat expansion: large CTA/CTG repeat alleles are more common in ataxic patients, including those with SCA6

We analyzed the SCA8 CTA/CTG repeat in a large group of Japanese subjects. The frequency of large alleles (85-399 CTA/CTG repeats) was 1.9% in spinocerebellar ataxia (SCA), 0.4% in Parkinson disease, 0.3% in Alzheimer disease, and 0% in a healthy control group; the frequency was significantly higher in the group with SCA than in the control group. Homozygotes for large alleles were observed only in the group with SCA. In five patients with SCA from two families, a large SCA8 CTA/CTG repeat and a large SCA6 CAG repeat coexisted. Age at onset was correlated with SCA8 repeats rather than SCA6 repeats in these five patients. In one of these families, at least one patient showed only a large SCA8 CTA/CTG repeat allele, with no large SCA6 CAG repeat allele. We speculate that the presence of a large SCA8 CTA/CTG repeat allele influences the function of channels such as alpha(1A)-voltage-dependent calcium channel through changing or aberrant splicing, resulting in the development of cerebellar ataxia, especially in homozygous patients.

LRRK2 mutations and risk variants in Japanese patients with Parkinson's disease

Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common genetic determinant of Parkinson's disease (PD) in European-derived populations, but far less is known about LRRK2 mutations and susceptibility alleles in Asians. To address this issue, we sequenced the LRRK2 coding region in 36 patients with familial PD, then genotyped variants of interest in an additional 595 PD cases and 1,641 controls who were all of Japanese ancestry. We also performed a meta-analysis of studies on G2385R, a polymorphism previously reported to associate with PD. One pathogenic (G2019S) and one putative pathogenic (R1067Q) mutation were each observed in two patients with sporadic PD. The overall mutation frequency among patients was 0.6%. G2385R was highly associated with PD under a dominant model in our dataset (adjusted OR, 1.83; 95% CI, 1.31-2.54; P = 3.3 x 10(-4)) and similar results were seen in the meta-analysis (summary OR assuming fixed effects, 2.55; 95% CI, 2.10-3.10). G2385R represents the first consistently replicated common PD susceptibility variant in a non-European population and its effect size is substantially greater than that reported for other well-validated genetic risk factors for the disease. However, LRRK2 mutations appear to be rare among Japanese patients with PD.

Contribution of the interleukin-1beta gene polymorphism in multiple system atrophy

We studied genetic polymorphisms in the promoter region at position -511 of the interleukin (IL) -1beta gene (IL-1B-511) and at position -889 of the IL-1alpha gene (IL-1A-889), in 111 Japanese patients with multiple system atrophy (MSA) and 160 controls. The distribution of IL-1B-511 was significantly different between MSA patients and controls, because of the under-representation of patients with homozygotes for allele 2 (IL-1B-511*2), a high producer of IL-1beta. The frequency of IL-1A-889*2, a high secretor of IL-1alpha, was also decreased in MSA patients. Our findings suggest that abnormal cytokine expression may be implicated in the pathogenesis of MSA.

Enhanced antitumor efficacy of a combination of CPT-11, a new derivative of camptothecin, and cisplatin against human lung tumor xenografts

The objective of this study was to evaluate the antitumor efficacy of combined use of 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin (CPT-11) and cisplatin (CDDP). The antitumor activities of CPT-11, CDDP and their combination against 3 human lung tumor xenografts were estimated using congenitally athymic BALB/c (nu/nu) mice. The doses were 47 mg/kg for CPT-11 and 6 mg/kg for CDDP on days 1, 5 and 9. In combination therapy, half of the single dosage of each agent was used. The doses were administered intraperitoneally. The antitumor activity and toxicity were evaluated in terms of the tumor volume and body weight change of mice, respectively. The combination therapy resulted in a statistically significant tumor regression compared to the use of only CPT-11 or CDDP in two tumor xenografts out of three. The toxicity of the combination therapy was no higher than that of CPT-11 or CDDP alone. These results suggest that the antitumor activity of the combination of CPT-11 and CDDP is superior to that of CPT-11 or CDDP alone.

Genetic studies in Parkinson's disease with an alpha-synuclein/NACP gene polymorphism in Japan

Dinucleotide repeat polymorphism has been observed in the promoter of the alpha-synuclein (alpha-SYN)/NAC precursor protein (NACP) gene. Alpha-SYN/NACP allele 3 (described by Xia et al. (Ann. Neurol., 40 (1996) 207), equivalent to allele 1 described by Krüger et al. (Ann. Neurol. 45 (1999) 611) is reported to be significantly more frequent among patients with sporadic Parkinson's disease (sPD) than controls. In this study, we genotyped the same alpha-SYN/NACP polymorphism in Japanese sPD patients and healthy controls, but found that any aliele showed no significant difference between the two groups.

Identification and haplotype analysis of LRRK2 G2019S in Japanese patients with Parkinson disease

LRRK2 G2019S is the most common known cause of Parkinson disease (PD) in patients of European origin, but little is known about its distribution in other populations. The authors identified two of 586 Japanese patients with PD heterozygous for the mutation who shared a haplotype distinct from that observed in Europeans. This suggests that G2019S originated from separate founders in Europe and Japan and is more widely dispersed than previously recognized.

Possible reduced penetrance of expansion of 44 to 47 CAG/CAA repeats in the TATA-binding protein gene in spinocerebellar ataxia type 17

BACKGROUND

Spinocerebellar ataxia type 17 (SCA17) is an autosomal dominant cerebellar ataxia caused by expansion of CAG/CAA trinucleotide repeats in the TATA-binding protein (TBP) gene. Because the number of triplets in patients with SCA17 in previous studies ranged from 43 to 63, the normal number of trinucleotide units has been considered to be 42 or less. However, some healthy subjects in SCA17 pedigrees carry alleles with the same number of expanded repeats as patients with SCA17.

OBJECTIVE

To investigate the minimum number of CAG/CAA repeats in the TBP gene that causes SCA17.

DESIGN

We amplified the region of the TBP gene containing the CAG/CAA repeat by means of polymerase chain reaction and performed fragment and sequence analyses.

PATIENTS

The subjects included 734 patients with SCA (480 patients with sporadic SCA and 254 patients with familial SCA) without CAG repeat expansions at the SCA1, SCA2, Machado-Joseph disease, SCA6, SCA7, or dentatorubral-pallidolluysian atrophy loci, with 162 healthy subjects, 216 patients with Parkinson disease, and 195 with Alzheimer disease as control subjects.

RESULTS

Eight patients with SCA possessed an allele with more than 43 CAG/CAA repeats. Among the non-SCA groups, alleles with 43 to 45 repeats were seen in 3 healthy subjects and 2 with Parkinson disease. In 1 SCA pedigree, a patient with possible SCA17 and her healthy sister had alleles with 45 repeats. A 34-year-old man carrying alleles with 47 and 44 repeats (47/44) had developed progressive cerebellar ataxia and myoclonus at 25 years of age, and he exhibited dementia and pyramidal signs. He was the only affected person in his pedigree, although his father and mother carried alleles with mildly expanded repeats (44/36 and 47/36, respectively). In another pedigree, 1 patient carried a 43-repeat allele, whereas another patient had 2 normal alleles, indicating that the 43-repeat allele may not be pathologic in this family.

CONCLUSIONS

We estimate that 44 CAG/CAA repeats is the minimum number required to cause SCA17. However, the existence of unaffected subjects with mildly expanded triplets suggests that the TBP gene mutation may not penetrate fully. Homozygosity of alleles with mildly expanded triplet repeats in the TBP gene might contribute to the pathologic phenotype.

Transcriptional activity of a fluorinated vitamin D analog on VDR-RXR-mediated gene expression

The transcriptional activity of the hexafluorinated derivative of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3], 26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D3 [F6-1,25-(OH)2D3], was examined in cultured cells by a transient expression assay (CAT assay) using expression vectors for the rat nuclear vitamin D3 receptor (VDR) and the rat 9-cis-retinoic acid receptor (RXR beta), and a reporter plasmid containing a consensus vitamin D3 response element (VDRE) consisting of two directly repeated AGGTCA motifs spaced by 3 bp (DR3). At physiological concentrations, the transcriptional activity of F6-1,25-(OH)2D3 was 2-4 times more potent than that of 1,25-(OH)2D3 in both nontarget (HeLa) and target (UMR106) cells for 1,25-(OH)2D3. The transcriptional activity of F6-1,25-(OH)2D3 was also higher when the endogenous target gene (osteopontin), which has a VDRE related to the DR3 in its promoter, was induced. A gel-shift assay using DR3 as a probe and in vitro synthesized receptors showed that the ligand-induced DNA binding of VDR required RXR to form a heterodimer. Moreover, in this assay we found that F6-1,25-(OH)2D3 induced the receptor-DNA complex at a 10-fold lower concentration than 1,25-(OH)2D3 without influencing the dissociation kinetics. However, the binding affinity of F6-1,25-(OH)2D3 for VDR was slightly lower than that of 1,25-(OH)2D3. The increased DNA binding of ligand-bound VDR by introducing hexafluorines into 1,25-(OH)2D3 may potentiate the transcriptional activity. Thus, the higher biological activity of F6-1,25-(OH)2D3 may be exerted at least in part by enhanced transcriptional activity.

Screening for TARDBP mutations in Japanese familial amyotrophic lateral sclerosis

TAR-DNA-binding protein 43 (TDP-43), encoded by the TARDBP gene on chromosome 1p36.22, has been identified as the major pathological protein in abnormal inclusions in neurons and glial cells in sporadic amyotrophic lateral sclerosis (SALS), SOD1-negative familial ALS (FALS) and frontotemporal lobar dementia (FTLD). Twenty mutations of TARDBP in SOD1-negative FALS and SALS cases have been reported so far. To investigate the presence and frequency of TARDBP mutations in Japanese SOD1-negative FALS patients, we performed mutational screening of TARDBP in 30 SOD1-negative FALS patients. An N352S mutation was found in one case of FALS, but no TARDBP mutations were found in cases of SALS. It was thought that this mutation increases TDP-43 phosphorylation. This might lead to impaired nuclear cytoplasmic transport or protein-protein interaction, thereby leading to TDP-43 accumulation.

Immunoreactivity of valosin-containing protein in sporadic amyotrophic lateral sclerosis and in a case of its novel mutant

Background

Mutations in the valosin-containing protein (VCP) gene were first found to cause inclusion- body myopathy with early-onset Paget disease and frontotemporal dementia (IBMPFD). Mutations in the VCP gene were later reported to occur in familial amyotrophic lateral sclerosis (ALS). But the role of VCP in the neurodegenerative processes that occur in ALS remains unknown. The purpose of the present study was to elucidate the role of VCP in the neurodegeneration seen in sporadic and VCP mutant ALS.

Results

Immunohistochemistry demonstrated that the frequency of distinct VCP-positive nuclei of spinal motor neurons of patients with sporadic ALS (SALS) and the ALS with VCP novel mutation (ALS-VCP, M158V) was increased, compared with that of the control cases. No VCP-positive inclusion bodies were observed in SALS patients, a ALS-VCP patient or in control subjects. Neuropathologic examination of the ALS-VCP case showed loss of motor neurons, the presence of Bunina bodies, and degeneration of the corticospinal tracts. Bunina bodies detected in this case were confirmed to show immunohistochemical and ultrastructural features similar to those previously described. Furthermore, neuronal intracytoplasmic inclusions immunopositive for TAR DNA-binding protein 43 kDa (TDP-43), phosphorylated TDP-43, ubiquitin (Ub), p62, and optineurin were identified in the spinal and medullary motoneurons, but not in the neocortex. Gene analysis of this ALS-VCP patient confirmed the de novo mutation of M158V, which was not found in control cases; and bioinformatics using several in silico analyses showed possible damage to the structure of VCP. Immunocytochemical study of cultured cells showed increased cytoplasmic translocation of TDP-43 in cells transfected with several mutant VCP including our patient’s compared with wild-type VCP.

Conclusion

These findings support the idea that VCP is associated with the pathomechanism of SALS and familial ALS with a VCP mutation, presumably acting through a dominant-negative mechanism.

Electronic supplementary material

The online version of this article (doi:10.1186/s40478-014-0172-0) contains supplementary material, which is available to authorized users.

Pro-gastrin-releasing peptide (31-98) as a tumour marker of small-cell lung cancer: comparative evaluation with neuron-specific enolase

We attempted to clarify whether serum levels of a carboxy-terminal fragment of ProGRP, ProGRP(31-98), could serve as a more accurate tumour marker in patients with SCLC than neuron-specific enolase (NSE). ProGRP(31-98) and NSE were measured retrospectively in 101 newly diagnosed untreated patients with SCLC, 111 with non-small-cell lung cancer (NSCLC) and 114 patients with non-malignant lung diseases. ProGRP(31-98) and NSE levels were determined using a sandwich enzyme-linked immunosorbent assay. Sensitivity in SCLC patients was 72.3% for ProGRP(31-98) and 62.4% for NSE. Comparing the area under curve (AUC) of 'receiver operator characteristics' of ProGRP(31-98) with that of NSE, ProGRP(31-98) was the more powerful marker in the diagnosis of SCLC (P = 0.0001). Serum levels of ProGRP(31-98) were higher in the 40 patients with extensive disease than in the 61 patients with limited disease (P = 0.0082). ProGRP(31-98) was significantly higher in patients with pure small-cell carcinoma than in patients with mixed small-cell/large-cell carcinoma (P = 0.02). In serial measurement in 16 patients responding to treatment, a high degree of correlation was noted between the decrease in serum ProGRP(31-98) levels and clinical response during the second week after treatment (P = 0.0045). These results indicate that the determination of serum ProGRP(31-98) levels plays an important role in the diagnosis and treatment of SCLC patients.

Lack of an association between cystatin C gene polymorphisms in Japanese patients with Alzheimer's disease

Associations between polymorphisms of the cystatin C gene (CST3) at 5' flanking region and exon 1 in Caucasian patients with late onset AD and exon 1 in a US study of late onset AD have been reported. Clinically diagnosed Japanese patients with AD and Japanese normal control subjects were assessed for the presence of polymorphisms of CST3. The authors could not confirm the previously reported association between CST3 polymorphisms and AD in Japan. Age had no effect on the CST3 genotype.

Evaluation of the interobserver agreement in the number of mitotic figures of breast carcinoma as simulation of quality monitoring in the Japan National Surgical Adjuvant Study of Breast Cancer (NSAS-BC) protocol

In the National Surgical Adjuvant Study for Breast Cancer (NSAS-BC), node-negative breast cancers were divided into higher- and lower-risk groups according to the histopathological nuclear grade given at individual collaborating hospitals, and the higher-risk group was entered into a randomized protocol of adjuvant therapy. Because the nuclear grade was the composite of nuclear atypia and mitotic counts, maintenance of interobserver agreement in mitotic counts was indispensable for the success of the protocol study. Fourteen pathologists participating in the protocol judged whether or not 20 photomicrographs suspected of showing mitotic cancer-cell figures truly showed mitoses. After standardizing the counting method, these pathologists counted the number of mitotic figures per 10 high-power fields of hematoxylin-eosin-stained main-tissue sections of 20 tumors. Areas where mitotic counts were considered to be the most frequent by each pathologist were compared for these tumors. For the judgment of whether the photomicrograph indicated mitosis, the level of interobserver agreement was moderate (kappa = 0.569). In the observations of 20 tumors, interobserver agreement level of mitotic counts was moderate (kappa = 0.506), that of nuclear atypia scoring was fair (kappa = 0.265), and that of nuclear grading was substantial (kappa = 0.633). The counted area was almost the same among the observers in 9 tumors, split into two areas in 6, and dispersed in 5. Concordance in judgment was achieved in 7 of the first 9 and in all of the third 5, but only in one of the second 6. The cause of discordance was mostly derived from tumor heterogeneity and the difference in the site where mitoses were counted. Interobserver agreement level was considered to be satisfactory, and it was expected that the case entry would be performed appropriately in the protocol study. The selection of the counting area was confirmed to be important for the acquisition of high-level agreement level in mitotic counts.

Effect of low-concentration chlorine dioxide gas against bacteria and viruses on a glass surface in wet environments

Aims:  To evaluate the efficacy of low‐concentration chlorine dioxide (ClO₂) gas against model microbes in the wet state on a glass surface.

Methods and Results:  We set up a test room (39 m³) and the ClO₂ gas was produced by a ClO₂ gas generator that continuously releases a constant low‐concentration ClO₂ gas. Influenza A virus (Flu‐A), feline calicivirus (FCV), Staphylococcus aureus and Escherichia coli were chosen as the model microbes. The low‐concentration ClO₂ gas (mean 0·05 ppmv, 0·14 mg m⁻³) inactivated Flu‐A and E. coli (>5 log₁₀ reductions) and FCV and S. aureus (>2 log₁₀ reductions) in the wet state on glass dishes within 5 h.

Conclusions:  The treatment of wet environments in the presence of human activity such as kitchens and bathrooms with the low‐concentration ClO₂ gas would be useful for reducing the risk of infection by bacteria and viruses residing on the environmental hard surfaces without adverse effects.

Significance and Impact of the Study:  This study demonstrates that the low‐concentration ClO₂ gas (mean 0·05 ppmv) inactivates various kinds of microbes such as Gram‐positive and Gram‐negative bacteria, enveloped and nonenveloped viruses in the wet state.

PLK1-mediated phosphorylation of WDR62/MCPH2 ensures proper mitotic spindle orientation

Primary microcephaly (MCPH) is an autosomal recessive disorder characterized by congenital reduction of head circumference. Here, we identified compound heterozygous mutations c.731 C > T (p.Ser 244 Leu) and c.2413 G > T (p.Glu 805 X) in the WDR62/MCPH2 gene, which encodes the mitotic centrosomal protein WDR62, in two siblings in a Japanese family with microcephaly using whole-exome sequencing. However, the molecular and cellular pathology of microcephaly caused by WDR62/MCPH2 mutation remains unclear. To clarify the physiological role of WDR62, we used the CRISPR/Cas9 system and single-stranded oligonucleotides as a point-mutation-targeting donor to generate human cell lines with knock-in of WDR62/MCPH2 c.731 C > T (p.Ser 244 Leu) missense mutation. In normal metaphase, the mitotic spindle forms parallel to the substratum to ensure symmetric cell division, while WDR62/MCPH2-mutated cells exhibited a randomized spindle orientation caused by the impaired astral microtubule assembly. It was shown that a mitotic kinase, Polo-like kinase 1 (PLK1), is required for the maintenance of spindle orientation through astral microtubule development. In this study, we demonstrated that WDR62 is a PLK1 substrate that is phosphorylated at Ser 897, and that this phosphorylation at the spindle poles promotes astral microtubule assembly to stabilize spindle orientation. Our findings provide insights into the role of the PLK1-WDR62 pathway in the maintenance of proper spindle orientation.

Exome sequencing reveals a novel TTC19 mutation in an autosomal recessive spinocerebellar ataxia patient

Background

Spinocerebellar ataxias (SCAs) are heterogeneous diseases characterized by progressive cerebellar ataxia associated with dysarthria, oculomotor abnormalities, and mental impairment. To identify the causative gene, we performed exome sequencing on a Japanese patient clinically diagnosed with recessive SCA.

Method

The patient is a 37-year-old Japanese woman with consanguineous parents. The head magnetic resonance imaging (MRI) showed cerebellar atrophy and T1 low/T2 high intensity at the bilateral inferior olives. Single-nucleotide polymorphism (SNP) genotyping and next-generation sequencing were performed, and the variants obtained were filtered and prioritized.

Results

After these manipulations, we identified a homozygous nonsense mutation of the TTC19 gene (p.Q277*). TTC19 has been reported to be a causative gene of a neurodegenerative disease in Italian and Portuguese families and to be involved in the pathogenesis of mitochondrial respiratory chain complex III (cIII) deficiency. This report is the first description of a TTC19 mutation in an Asian population. Clinical symptoms and neuroimaging are consistent with previous reports. The head MRI already showed abnormal features four years before her blood lactate and pyruvate levels were elevated.

Conclusions

We should consider the genetic analysis of TTC19 when we observe such characteristic MRI abnormalities. Genes associated with mitochondrial function cause many types of SCAs; the mutation we identified should help to elucidate the pathology of these disorders.

Identification of a new family of spinocerebellar ataxia type 14 in the Japanese spinocerebellar ataxia population by the screening of PRKCG exon 4

Spinocerebellar ataxia type 14 (SCA14) is an autosomal dominant neurodegenerative disorder characterized by cerebellar ataxia and intermittent axial myoclonus. Various mutations have been found in the PRKCG gene encoding protein kinase C gamma in SCA14 families. Most of those mutations have been found in exon 4 of the PRKCG gene. We performed polymerase chain reaction (PCR)-based screening to clarify the approximate morbidity rate of the disease in the Japanese SCA population. We screened exon 4 of the PRKCG gene in 882 SCA patients with undefined etiologies using denaturing high-performance liquid chromatography and subsequent direct sequencing. We found a novel C/T missense mutation with a Ser119-to-Phe substitution (S119F) in 2 patients and subsequently found that they belonged to the same family. This S119F mutation was not found in 259 control individuals. Further PCR-based analysis revealed an additional 5 members with the same mutation in this family. Cerebellar ataxia was manifested in 5 of those 7 members. The main symptom in 4 of the 5 affected members was pure cerebellar ataxia with late onset. They had no myoclonus, extrapyramidal signs, ophthalmoplegia, or intellectual disturbance, some of which were found in previously reported SCA families. One patient showed intractable epilepsy, severe walking disturbance, and trunk ataxia with early onset. The results of this study suggest that the frequency of SCA14 in the Japanese SCA population is very low.

Histologic changes in small cell lung carcinoma after treatment

BACKGROUND

Small cell lung carcinoma (SCLC) has been divided into three subtypes: pure SCLC, mixed small cell/large cell carcinoma (mixed SC/LC), and combined SCLC. Patients with mixed SC/LC show a worse prognosis than those with pure SCLC.

METHODS

Persistence of histologic subtype in SCLC in the primary sites during the course of treatment or in the different organs at autopsy was examined. For this purpose, biopsy or cytologic specimens before chemotherapy, and autopsy specimens from 175 patients with SCLC were reviewed. They included 147 (84%) men and 28 (16%) women with an age range of 29-83 (median, 65) years.

RESULTS

The frequency of mixed SC/LC in the primary sites was statistically higher in autopsy (14.3%) than that in biopsy or cytology specimens (8.6%) (P < 0.05). At autopsy, involved organs were categorized into two groups according to frequency of appearance of mixed SC/LC, i.e., a higher frequency group, including the liver (31 of 85; 36.4%), adrenal gland (15 of 56; 26.8%), brain (6 of 9; 66.7%), and extrathoracic lymph nodes (17 of 59; 28.8%) and a lower frequency group, including the lung (metastatic sites) (12 of 102; 11.8%), pleura (8 of 74; 10.8%), and intrathoracic lymph nodes (12 of 94; 12.8%). The difference in frequency between these two groups was statistically significant (P < 0.05).

CONCLUSIONS

These findings suggest that primary pure SCLC can progress to mixed SC/LC with an increased potential for distant metastasis.

Chlorine dioxide is a more potent antiviral agent against SARS-CoV-2 than sodium hypochlorite

BACKGROUND

A new coronavirus (SARS-CoV-2) abruptly emerged in Wuhan, China, in 2019 and rapidly spread globally to cause the COVID-19 pandemic.

AIM

To examine the anti-SARS-CoV-2 activity of the potent disinfectant Cleverin, the major disinfecting component of which is chlorine dioxide (ClO₂); and to compare the results with that of sodium hypochlorite in the presence or absence of 0.5% or 1.0% foetal bovine serum (FBS).

METHODS

Concentrated SARS-CoV-2 viruses were treated with various concentrations of ClO₂ and sodium hypochlorite and 50% tissue culture infective dose was calcurated to evaluate the antiviral activity of each chemical.

FINDINGS

When SARS-CoV-2 viruses were treated with 0.8 ppm ClO₂ or sodium hypochlorite, viral titre was decreased only by 1 log₁₀ TCID₅₀/mL in 3 min. However, the viral titre was decreased by more than 4 log₁₀ TCID₅₀/mL when treated with 80 ppm of each chemical for 10 s regardless of presence or absence of FBS. It should be emphasized that treatment with 24 ppm of ClO₂ inactivated more than 99.99% SARS-CoV-2 within 10 s or 99.99% SARS-CoV-2 in 1 min in the presence of 0.5% or 1.0% FBS, respectively. By contrast, 24 ppm of sodium hypochlorite inactivated only 99% or 90% SARS-CoV-2 in 3 min under similar conditions. Notably, except for ClO₂, the other components of Cleverin such as sodium chlorite, decaglycerol monolaurate, and silicone showed no significant antiviral activity.

CONCLUSION

Altogether, the results strongly suggest that although ClO₂ and sodium hypochlorite are strong antiviral agents in absence of organic matter but in presence of organic matter, ClO₂ is a more potent antiviral agent against SARS-CoV-2 than sodium hypochlorite.

Dinucleotide repeat polymorphisms in the neprilysin gene are not associated with sporadic Alzheimer's disease

In the pathological process of Alzheimer's disease (AD), deposition of amyloid beta-peptide (A beta) in the brain parenchyma plays an important role. Neprilysin (NEP), a neutral endopeptidase, degrades A beta, and it is postulated that decreased NEP activity may contribute to the development of AD by promoting the accumulation of A beta. The human NEP gene possesses four dinucleotide repeat polymorphisms, and it is possible that these polymorphisms regulate the NEP expression levels and influence the pathological cascade of AD. Therefore, we investigated the association of these polymorphisms with AD. We performed genotyping of each polymorphism in 201 Japanese sporadic AD patients and 208 Japanese controls. There were no significant differences between the AD and control groups in allele frequencies of each polymorphism. We conclude that these polymorphisms in the NEP gene do not contribute to genetic risk factors for sporadic AD.