Molecular genetic analysis of 30 families with Joubert syndrome.

Joubert syndrome (JS) is rare recessive disorders characterized by the combination of hypoplasia/aplasia of the cerebellar vermis, thickened and elongated superior cerebellar peduncles, and a deep interpeduncular fossa which is defined by neuroimaging and is termed the 'molar tooth sign'. JS is genetically highly heterogeneous, with at least 29 disease genes being involved. To further understand the genetic causes of JS, we performed whole-exome sequencing in 24 newly recruited JS families. Together with six previously reported families, we identified causative mutations in 25 out of 30 (24 + 6) families (83.3%). We identified eight mutated genes in 27 (21 + 6) Japanese families, TMEM67 (7/27, 25.9%) and CEP290 (6/27, 22.2%) were the most commonly mutated. Interestingly, 9 of 12 CEP290 disease alleles were c.6012-12T>A (75.0%), an allele that has not been reported in non-Japanese populations. Therefore c.6012-12T>A is a common allele in the Japanese population. Importantly, one Japanese and one Omani families carried compound biallelic mutations in two distinct genes (TMEM67/RPGRIP1L and TMEM138/BBS1, respectively). BBS1 is the causative gene in Bardet-Biedl syndrome. These concomitant mutations led to severe and/or complex clinical features in the patients, suggesting combined effects of different mutant genes.

Survival of fetuses with severe oligohydramnios.

OBJECTIVE: The aim of the present study was to identify predictive data on the short-term outcomes of fetuses with oligohydramnios. MATERIALS AND METHODS: A retrospective study of all pregnancies diagnosed with oligohydramnios was performed. RESULTS: A total of 17 fetuses (seven males, seven females, and three unknown) with oligohydramnios were treated from 2004 to 2011. Oligohydramnios was first diagnosed at a 21.6 ± 4.2 weeks gestation. Terminations of pregnancy before 22 weeks were identified in five cases, and intrauterine fetal deaths occurred in two cases. Ten neonates were born alive, five cases survived over 28 days, and five cases died within 48 hours. Prognostic factors for survival included birth weight (2,457 ± 480 grams in survivors vs. 1973 ± 124 grams in non-survivors; p < 0.05) and the mean amniotic fluid index (AFI) (2.32 ± 1.19 cm in survivors vs. 0.46 ± 0.68 cm in non-survivors;p < 0.05). CONCLUSION: All patients who survived had a mean AFI > 1.0 cm.

Targeted next-generation sequencing in the diagnosis of neurodevelopmental disorders.

We developed a next-generation sequencing (NGS) based mutation screening strategy for neurodevelopmental diseases. Using this system, we screened 284 genes in 40 patients. Several novel mutations were discovered. Patient 1 had a novel mutation in ACTB. Her dysmorphic feature was mild for Baraitser-Winter syndrome. Patient 2 had a truncating mutation of DYRK1A. She lacked microcephaly, which was previously assumed to be a constant feature of DYRK1A loss of function. Patient 3 had a novel mutation in GABRD gene. She showed Rett syndrome like features. Patient 4 was diagnosed with Noonan syndrome with PTPN11 mutation. He showed complete agenesis of corpus callosum. We have discussed these novel findings.

Mutations in COG2 encoding a subunit of the conserved oligomeric golgi complex cause a congenital disorder of glycosylation.

The conserved oligomeric Golgi (COG) complex is involved in intra-Golgi retrograde trafficking, and mutations in six of its eight subunits have been reported in congenital disorders of glycosylation (CDG). Here we report a patient showing severe acquired microcephaly, psychomotor retardation, seizures, liver dysfunction, hypocupremia, and hypoceruloplasminemia. Analysis of his serum glycoproteins revealed defects in both sialylation and galactosylation of glycan termini. Trio-based whole-exome sequencing identified two heterozygous mutations in COG2: a de novo frameshift mutation [c.701dup (p.Tyr234*)] and a missense mutation [c.1900T > G (p.Trp634Gly)]. Sequencing of cloned reverse-transcription polymerase chain reaction (RT-PCR) products revealed that both mutations were located on separate alleles, as expected, and that the mutant transcript harboring the frameshift mutation underwent degradation. The c.1900T > G (p.Trp634Gly) mutation is located in a domain highly conserved among vertebrates and was absent from both the public database and our control exomes. Protein expression of COG2, along with COG3 and COG4, was decreased in fibroblasts from the patient. Our data strongly suggest that these compound heterozygous mutations in COG2 are causative of CDG.

Perinatal management of neonatal alloimmune thrombocytopenia associated with anti-group A antibody.

OBJECTIVE: To prevent neonatal alloimmune thrombocytopenia due to anti-group A antibody perinatal management was performed. BACKGROUND: We previously reported a case of severe intracranial haemorrhage associated with neonatal alloimmune thrombocytopenia due to anti-group A isoantibody. MATERIAL/METHODS: A 40-year-old Japanese woman, gravida 4 para 1, was pregnant with her second baby. The previous sibling developed severe thrombocytopenia and died 10 days after birth due to intracranial haemorrhage. He was diagnosed with neonatal alloimmune thrombocytopenia; the causative antibody was found to be the anti-group A antibody. Prednisone was started at 7 weeks' gestational age. Intravenous immunoglobulin 1 g kg(-1) week(-1) was started at 29 weeks' gestational age and continued to delivery. Serological studies and genotyping were performed. RESULTS: The second boy was delivered at 33 weeks' gestational age by caesarean section. He was discharged without intracranial haemorrhage or thrombocytopenia. The anti-group A antibody titre in the maternal serum was 2048-4096 (normal range: 4-64). The anti-group A antibody titre in the newborn's serum was 4. Cross-matching between the maternal serum and the paternal platelets was positive. CONCLUSION: Owing to the history of neonatal alloimmune thrombocytopenia causing intracranial haemorrhage and death of the previous sibling, strict follow-up of the subsequent pregnancy was conducted.

Long-term entecavir therapy results in falls in serum hepatitis B surface antigen levels and seroclearance in nucleos(t)ide-naïve chronic hepatitis B patients.

Entecavir (ETV) is reported to result in suppression of hepatitis B virus DNA (HBV DNA) replication with minimal drug resistance. However, information on the long-term effect of such therapy on serum hepatitis B surface antigen (HBsAg) level and elimination of HBsAg is not available. ETV therapy was started in 553 nucleos(t)ide-naïve patients with chronic hepatitis B infection (HBeAg positive: 45%) in our hospital. Serum HBsAg levels were measured serially by the Architect assay. The median baseline HBsAg was 2180 IU/mL (0.12-243 000 IU/mL), and median follow-up period was 3.0 years, with 529, 475, 355, 247 and 163 patients followed-up for 1, 2, 3, 4 and 5 years, respectively. At year 5, the mean log HBsAg decline from baseline was -0.48 log IU/mL, and the cumulative HBsAg clearance rate was 3.5%. Multivariate analysis identified HBV DNA level at baseline (<3.0 log copies IU/mL, odd ratio = 10.2; 95% confidence interval = 1.87-55.5, P = 0.007) and HBsAg level (<500 IU/mL, odd ratio = 29.4; 95% confidence interval = 2.80-333, P = 0.005) as independent predictors of HBsAg seroclearance. These results indicate that although serum HBsAg level declines gradually during ETV therapy, HBsAg seroclearance remains a rare event.

Inherited microdeletions in the Angelman and Prader-Willi syndromes define an imprinting centre on human chromosome 15.

A subset of patients with Angelman and Prader-Willi syndrome have apparently normal chromosomes of biparental origin, but abnormal DNA methylation at several loci within chromosome 15q11-13, and probably have a defect in imprinting. Using probes from a newly established 160-kb contig including D15S63 (PW71) and SNRPN, we have identified inherited microdeletions in two AS families and three PWS families. The deletions probably affect a single genetic element that we term the 15q11-13 imprinting centre (IC). In our model, the IC regulates the chromatin structure, DNA methylation and gene expression in cis throughout 15q11-13. Mutations of the imprinting centre can be transmitted silently through the germline of one sex, but appear to block the resetting of the imprint in the germline of the opposite sex.

A novel maternally expressed gene, ATP10C, encodes a putative aminophospholipid translocase associated with Angelman syndrome.

Lack of a maternal contribution to the genome at the imprinted domain on proximal chromosome 15 causes Angelman syndrome (AS) associated with neurobehavioral anomalies that include severe mental retardation, ataxia and epilepsy. Although AS patients have infrequent mutations in the gene encoding an E6-AP ubiquitin ligase required for long-term synaptic potentiation (LTP), most cases are attributed to de novo maternal deletions of 15q11-q13. We report here that a novel maternally expressed gene, ATP10C, maps within the most common interval of deletion and that ATP10C expression is virtually absent from AS patients with imprinting mutations, as well as from patients with maternal deletions of 15q11-q13.

Imprint switching on human chromosome 15 may involve alternative transcripts of the SNRPN gene.

Imprinting on human chromosome 15 is regulated by an imprinting centre, which has been mapped to a 100-kb region including exon 1 of SNRPN. From this region we have identified novel transcripts, which represent alternative transcripts of the SNRPN gene. The novel exons lack protein coding potential and are expressed from the paternal chromosome only. We have also identified intragenic deletions and a point mutation in patients who have Angelman or Prader-Willi syndrome due to a parental imprint switch failure. This suggests that imprint switching on human chromosome 15 may involve alternative SNRPN transcripts.

Exploration and characterization of genes involved in the synthesis of diterpene defence secretion in nasute termite soldiers.

Nasutitermes takasagoensis soldiers defend their colonies using characteristic diterpenes. Diterpenes are thought to be synthesized in the frontal gland cells surrounding the gland reservoir. To identify the genes involved in diterpene synthesis, a cDNA library was prepared from the frontal gland cells and exhaustively sequenced using a 454 pyrosequencer (GS Junior; Roche, Branford, CT, USA). A total of 50,290 clean sequences were assembled into 1111 contigs, which were grouped into 774 genes (isogroups). Based on sequence similarity with known proteins, we identified seven genes encoding the following four enzymes associated with diterpene synthesis: 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase (HMGS), HMG-CoA reductase (HMGR), farnesyl diphosphate synthase, and geranylgeranyl diphosphate synthases. The expression levels of two enzymes, HMGS and HMGR, involved in the mevalonate pathway were examined, assuming that the site of the defensive terpenoid synthesis strongly activates the mevalonate pathway, which produces a precursor of terpenoids. Real-time quantitative reverse-transcriptase PCR confirmed significantly higher expression of HMGS and HMGR in the heads of soldiers. We then divided the head into three parts and found that the expression levels of HMGS and HMGR were significantly higher in the part containing class 1 secretory cells of the frontal gland. Overall, the results suggested that the mevalonate pathway for diterpene synthesis occurs in class 1 cells around the frontal gland reservoir.

Visualization of ATP with luciferin-luciferase reaction in mouse skeletal muscles using an "in vivo cryotechnique".

Adenosine triphosphate (ATP) is a well-known energy source for muscle contraction. In this study, to visualize localization of ATP, a luciferin-luciferase reaction (LLR) was performed in mouse skeletal muscle with an "in vivo cryotechnique" (IVCT). First, to confirm if ATP molecules could be trapped and detected after glutaraldehyde (GA) treatment, ATP was directly attached to glass slides with GA, and LLR was performed. The LLR was clearly detected as an intentional design of the ATP attachment. The intensity of the light unit by LLR was correlated with the concentration of the GA-treated ATP in vitro. Next, LLR was evaluated in mouse skeletal muscles with IVCT followed by freeze-substitution fixation (FS) in acetone-containing GA. In such tissue sections the histological structure was well maintained, and the intensity of LLR in areas between muscle fibers and connective tissues was different. Moreover, differences in LLR among muscle fibers were also detected. For the IVCT-FS tissue sections, diaminobenzidine (DAB) reactions were clearly detected in type I muscle fibers and erythrocytes in capillaries, which demonstrated flow shape. Thus, it became possible to perform microscopic evaluation of the numbers of ATP molecules in the mouse skeletal muscles with IVCT, which mostly reflect living states.

MERRF/MELAS overlap syndrome: a double pathogenic mutation in mitochondrial tRNA genes.

BACKGROUND: Myoclonic epilepsy with ragged-red fibres (MERRF) and mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) are established phenotypes of mitochondrial encephalomyopathy. The m.8356T>C transition in the mitochondrial tRNA(Lys) gene is a pathogenic mutations of MERRF. The m.3243A>G transition in the mitochondrial tRNA(Leu) gene is detected in most MELAS patients. Although previous analyses of double mutations in mitochondrial DNA (mtDNA) were useful for discussing their nature, many unsolved questions remain. OBJECTIVE: To describe the clinical and genetic features of a family with the above mtDNA double-point mutations and discuss the role of double mtDNA mutations in diverse clinical features in the family. PATIENTS AND METHODS: The proband was a 23-year-old woman with MERRF harbouring m.8356T>C and m.3243A>G transitions in mitochondrial tRNA genes. We assessed clinical aspects of her and those of her three relatives and performed mutation analyses on their mtDNA. RESULTS: Phenotypes of the four patients were MERRF, MERRF/MELAS overlap syndrome and asymptomatic carrier. We hypothesise that the course of the phenotype of this family begins with MERRF and is followed by MELAS. This double mutation was heteroplasmic in blood of all four patients but with different rates in each patient, while m.8356T>C appeared homoplasmic and m.3243A>G was heteroplasmic in muscle of the two examined cases. No other mutations were detected in the total mtDNA sequence in this family. CONCLUSIONS: This is the first reported case of a double-point mutation in mtDNA, both of which were heteroplasmic and pathogenic for the established phenotypes.

Parthenogenetic chimaerism/mosaicism with a Silver-Russell syndrome-like phenotype.

INTRODUCTION: We report a 34-year-old Japanese female with a Silver-Russell syndrome (SRS)-like phenotype and a mosaic Turner syndrome karyotype (45,X/46,XX). METHODS/RESULTS: Molecular studies including methylation analysis of 17 differentially methylated regions (DMRs) on the autosomes and the XIST-DMR on the X chromosome and genome-wide microsatellite analysis for 96 autosomal loci and 30 X chromosomal loci revealed that the 46,XX cell lineage was accompanied by maternal uniparental isodisomy for all chromosomes (upid(AC)mat), whereas the 45,X cell lineage was associated with biparentally derived autosomes and a maternally derived X chromosome. The frequency of the 46,XX upid(AC)mat cells was calculated as 84% in leukocytes, 56% in salivary cells, and 18% in buccal epithelial cells. DISCUSSION: The results imply that a parthenogenetic activation took place around the time of fertilisation of a sperm missing a sex chromosome, resulting in the generation of the upid(AC)mat 46,XX cell lineage by endoreplication of one blastomere containing a female pronucleus and the 45,X cell lineage by union of male and female pronuclei. It is likely that the extent of overall (epi)genetic aberrations exceeded the threshold level for the development of SRS phenotype, but not for the occurrence of other imprinting disorders or recessive Mendelian disorders.

Protection from anti-TCR/CD3-induced apoptosis in immature thymocytes by a signal through thymic shared antigen-1/stem cell antigen-2.

During T cell development in the thymus, the expression of thymic shared antigen-1 (TSA-1)/stem cell antigen-2 (Sca-2), a glycosylphosphatidylinositol (GPI)-anchored differentiation antigen, is developmentally regulated. The expression level of TSA-1 is the highest in most immature CD4- CD8- thymocytes, high in CD4+ CD8+ thymocytes, but barely detectable in mature CD4+ CD8- or CD4- CD8- thymocytes and peripheral T cells. We have previously shown that surface TSA-1 expression in peripheral T cells is induced upon activation and that anti-TSA-1 mAb inhibits the T cell receptor (TCR) signaling pathway in activated T cells. In the present study, we have analyzed a role of TSA-1 in thymic selection events, especially in TCR-mediated apoptosis. In in vitro experiments, anti-TSA-1 blocked anti-CD3-induced cell death of T cell hybridomas. When anti-TSA-1 was injected into newborn mice in vivo together with anti-CD3 epsilon or anti-TCR-beta, TCR/CD3-mediated apoptosis of thymocytes was almost completely blocked. The blockade of apoptosis was defined by the inhibition of, first, the decrease in total number of thymocytes; second, the decrease in percentages of CD4+ CD8+ thymocytes; and third, the induction of DNA fragmentation. However, anti-TSA-1 did not block either steroid- or radiation-induced apoptosis, indicating that a signal via TSA-1 does not inhibit a common pathway of thymocyte apoptosis. Since TCR-mediated apoptosis is pivotal in thymic ontogeny, these results suggest that TSA-1/Sca-2 is an important cell surface molecule regulating the fate of a developing T cell.

Occult hepatitis B virus infection increases hepatocellular carcinogenesis by eight times in patients with non-B, non-C liver cirrhosis: a cohort study.

An impact of serum hepatitis B virus (HBV) DNA on hepatocarcinogenesis has not been investigated in a cohort of patients with non-B, non-C cirrhosis. Eighty-two consecutive Japanese patients with cirrhosis, who showed negative hepatitis B surface antigen and negative anti-hepatitis C virus, were observed for a median of 5.8 years. Hepatitis B virus core (HBc) region and HBx region were assayed with nested polymerase chain reaction. Both of HBc and HBx DNA were positive in 9 patients (11.0%) and both were negative in 73. Carcinogenesis rates in the whole patients were 13.5% at the end of the 5th year and 24.6% at the 10th year. The carcinogenesis rates in the patients with positive DNA group and negative DNA group were 27.0% and 11.8% at the end of the 5th year, and 100% and 17.6% at the 10th year, respectively (P = 0.0078). Multivariate analysis showed that men (P = 0.04), presence of HBc and HBx DNA (hazard ratio: 8.25, P = 0.003), less total alcohol intake (P = 0.010), older age (P = 0.010), and association of diabetes (P = 0.005) were independently associated with hepatocellular carcinogenesis. Existence of serum HBV DNA predicted a high hepatocellular carcinogenesis rate in a cohort of patients with non-B, non-C cirrhosis.

Aberrant mitosis in fission yeast mutants defective in fatty acid synthetase and acetyl CoA carboxylase.

Two fission yeast temperature-sensitive mutants, cut6 and lsd1, show a defect in nuclear division. The daughter nuclei differ dramatically in size (the phenotype designated lsd, large and small daughter). Fluorescence in situ hybridization (FISH) revealed that sister chromatids were separated in the lsd cells, but appeared highly compact in one of the two daughter nuclei. EM showed asymmetric nuclear elongation followed by unequal separation of nonchromosomal nuclear structures in these mutant nuclei. The small nuclei lacked electron-dense nuclear materials and contained highly compacted chromatin. The cut6+ and lsd1+ genes are essential for viability and encode, respectively, acetyl CoA carboxylase and fatty acid synthetase, the key enzymes for fatty acid synthesis. Gene disruption of lsd1+ led to the lsd phenotype. Palmitate in medium fully suppressed the phenotypes of lsd1. Cerulenin, an inhibitor for fatty acid synthesis, produced the lsd phenotype in wild type. The drug caused cell inviability during mitosis but not during the G2-arrest induced by the cdc25 mutation. A reduced level of fatty acid thus led to impaired separation of non-chromosomal nuclear components. We propose that fatty acid is directly or indirectly required for separating the mother nucleus into two equal daughters.

Dietary intake and urinary excretion of selenium in the Japanese adult population: the INTERMAP Study Japan.

OBJECTIVE: This study is to examine the relationship between dietary selenium intake and 24-h urinary selenium excretion in Japanese population samples participating in the INTERMAP Study. METHODS: Using highly standardized methods, we assessed individual dietary selenium intake from four 24-h dietary recalls and measured urinary selenium excretion in two timed 24-h urine collections in 1145 Japanese participants (574 men and 571 women) ages 40-59 years in four areas of Japan. RESULTS: The medians of dietary selenium intake were 177.5 microg/day in men and 139.8 microg/day in women; the medians of 24-h urinary selenium excretion were 127.9 microg/day in men and 109.4 microg/day in women, that is, urinary excretion was estimated to be 73% of dietary intake in men and 77% in women. Dietary selenium intake was significantly correlated with 24-h urinary selenium excretion (r=0.24 in men, r=0.18 in women; P<0.001). With dietary selenium intake and urinary selenium excretion expressed per kg of body weight, values were similar for men and women (dietary intake, 2.7 microg/kg body weight in men and 2.5 microg/kg body weight in women; urinary excretion, 2.0 microg/kg body weight in men and 2.0 microg/kg body weight in women). CONCLUSION: Dietary intake and 24-h urinary excretion of selenium are related in the Japanese adult population.

Imprinting in Prader-Willi and Angelman syndromes.

Imprinted genes are marked in the germline and retain molecular memory of their parental origin, resulting in allelic expression differences during development. Abnormalities in imprinted inheritance occur in several genetic diseases and cancer, and are exemplified by the diverse genetic defects involving chromosome 15q11-q13 in Prader-Willi (PWS) and Angelman (AS) syndromes. PWS involves loss of function of multiple paternally expressed genes, while mutations in a single gene, UBE3A, which is subject to spatially restricted imprinting, occur in some AS patients. Identification of mutations in the imprinting process in PWS and AS has led to a definition of an imprinting center (IC), involving the promoter (in PWS) or an alternative transcript of the SNRPN gene (in AS). The IC regulates initiation of imprint switching for all genes in a 2 Mb imprinted domain during gametogenesis. Imprinting mutations define a novel mechanism of genetic disease because they have no direct effect in the affected patient but, rather, it is the parental germline effect of an IC mutation that leads to disease in the offspring.

Predominant area of brain lesions in neonates with herpes simplex encephalitis.

OBJECTIVE: Nonspecific manifestations and a varied distribution of brain lesions can delay the diagnosis of herpes simplex encephalitis (HSE) in neonates. The aim of this study was to report predominant brain lesions in neonatal HSE, and then to investigate the association between pattern of predominant brain lesions, clinical variables and neurodevelopmental outcome. STUDY DESIGN: A multicenter retrospective study was performed in neonates diagnosed with HSE between 2009 and 2014. Magnetic resonance (MR) images, including diffusion-weighted images, were obtained in the acute and chronic phase. RESULTS: Three predominant areas of brain injury could be defined based on characteristic MRI findings in 10 of the 13 infants (77%). The inferior frontal/temporal pole area was involved in five (38%) patients. The watershed distribution was present in six (46%) patients. Four (31%) infants involved the corticospinal tract area. No significant association was found between any predominant distribution of brain lesion pattern and sex, country, viral type or viral load. However, the corticospinal tract involvement was significantly associated with motor impairment (P=0.045). CONCLUSION: Three predominant areas of brain lesion could be recognized in neonatal HSE. Recognition of those areas can improve prediction of neurodevelopmental outcome.

Pattern of p53 gene mutations in breast cancers of women of the midwestern United States.

BACKGROUND: Mutation in the p53 gene is the most common genetic lesion in human cancers. The pattern of mutation in the p53 gene differs among cancers and may be a useful epidemiological tool for identification of factors contributing to carcinogenesis. PURPOSE: Our purpose was to determine if the pattern of p53 mutation in breast carcinomas in our population of women residing in the midwestern region of the United States is similar to the pattern of p53 mutation in breast cancers in patients from other regions of the United States and Europe and in other epithelial tumors. METHODS: With a technique we recently developed for the analysis of p53 mutations in genomic DNA from tumor cell clusters in touch preparations of solid tumors, we sequenced exons 5-9 and adjacent splice junctions of the gene in 44 breast cancers. Cells from each tumor were also stained with three monoclonal antibodies which recognize different epitopes of the p53 protein. RESULTS: We detected p53 mutations in 14 (32.6%) of 44 breast carcinomas. Only half of the mutations were missense changes. The other half included five microdeletions (three producing frame-shifts), one single-base substitution generating a stop codon, and one single-base substitution generating a splice junction abnormality. Nuclear expression of p53 antigen was present in eight of 44 cancers, including six with hemizygous missense mutations in the p53 gene. CONCLUSIONS: The pattern of p53 mutations in our breast cancer population differs from that reported in breast cancer populations by other investigators in which most p53 mutations were missense. Among 14 mutations in our population, at least five drastically altered the structure of p53, suggesting that a recessive mechanism of inactivation of the p53 gene may be more common than in other populations. IMPLICATIONS: Differences in the pattern of p53 mutation in breast cancers in Midwestern women and in breast cancers in other populations may reflect selection bias or small sample sizes currently available. However, our data are compatible with the possibility that an endogenous or exogenous factor influences p53 carcinogenesis in some women with breast cancer in the Midwest to a greater extent than in other regions of the United States and Europe.