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Biomedical subjects

Norio Niikawa

Publications and source records attributed to Norio Niikawa.

At least 37 records · Page 2Linked to original sources
PubMed2005

Analysis of the NSD1 promoter region in patients with a Sotos syndrome phenotype.

Sotos syndrome (SoS, OMIM#117550) is an overgrowth disorder characterized by excessive growth-especially in the first years of childhood-distinctive craniofacial features, and various degrees of mental retardation. Haploinsufficiency of the nuclear receptor binding SET domain containing protein 1 (NSD1) gene, due to either intragenic mutations or whole-gene microdeletions, is found in the majority of patients with SoS. However, in approximately 10-40% of patients with a typical SoS phenotype, no abnormalities are detected. In this study, hemizygous hypermethylation or genomic sequence abnormalities of the promoter region of NSD1 were hypothesized to be the underlying cause in patients with a SoS phenotype, but without confirmed NSD1 alterations. In 18 patients, including one patient with a reported hepatocellular carcinoma, the promoter region of NSD1 was analyzed. However, no hypermethylation or sequence abnormalities in the promoter region could be detected. It therefore seems unlikely that such abnormalities of NSD1 are a major culprit in patients with phenotypical SoS. Additional methods are necessary for detection of other genetic or epigenetic causes of SoS.

Base Sequence↗
PubMed2005

PAX9 and TGFB3 are linked to susceptibility to nonsyndromic cleft lip with or without cleft palate in the Japanese: population-based and family-based candidate gene analyses.

The prevalence of nonsyndromic cleft lip with or without cleft palate (CL/P) and cleft palate only (CPO) are believed to be higher in the Japanese than in Americans, Europeans or Africans. The purpose of this study was to investigate, in a Japanese population, relationships between CL/P or CPO and seven candidate genes (TGFB3, DLX3, PAX9, CLPTM1, TBX10, PVRL1, TBX22) that showed positive associations in other populations and are expressed in the oral/lip region in developing mice. We first searched for mutations in these genes among 112 CL/P and 16 CPO patients, and found a heterozygous missense mutation (640A > G, S214G) in exon 3 of PAX9 in two sibs with CL/P and their phenotypically normal mother from a Japanese family. A population-based case-control analysis and a family-based transmission disequilibrium test (TDT), using single nucleotide polymorphisms (SNPs), and two-SNP haplotypes of the genes, between the 112 CL/P cases with their parents and 192 controls indicated a significant association at one SNP site, IVS1 + 5321, in TGFB3 with a P-value of 0.0016. Population-based haplotyping revealed that the association was most significant for haplotype "A/A" consisting of IVS1 + 5321 and IVS1 - 1572; TDT also gave a P-value of 0.0252 in this haplotype.

Amino Acid Sequence↗
PubMed2005

Eosinophil infiltration in three patients with generalized atrophic benign epidermolysis bullosa from a Japanese family: molecular genetic and immunohistochemical studies.

Generalized atrophic benign epidermolysis bullosa (GABEB), a subtype of epidermolysis bullosa (EB), is an autosomal recessive skin disease characterized by derm-epidermal separation leading to skin fragility and atrophy and other associated abnormalities. Although a few reports demonstrated that eosinophils are infiltrating beneath bullas in infants with some types of EB, no such condition in adult GABEB patients has been known. Here we report on three adult patients with GABEB from a Japanese family, whose bullous skin lesions showed massive eosinophil infiltration. One of the three patients showed amyloid deposition at the intestine, kidney, and skin. Linkage analysis revealed that GABEB in the family was linked to COL17A1 with a maximum LOD score of 3.08. Mutation analysis identified in the three patients a homozygous insertional mutation, 209-210insCA, in exon 5 of COL17A1. The expression of mutated COL17A1 was confirmed by semiquantitative RT-PCR, but no signals for truncated COL17A1 protein were detected by the immunohistochemical studies using antibodies against BP180. Furthermore, no autoantibody against the mutant protein was detected by western blot analysis. It is thus less likely that autoantibody and/or a local immune reaction in their skin has a primary role in eosinophil infiltration in these patients.

Adult↗
PubMed2005

Neuron-specific relaxation of Igf2r imprinting is associated with neuron-specific histone modifications and lack of its antisense transcript Air.

The mouse insulin-like growth factor II receptor (Igf2r) gene and its antisense transcript Air are reciprocally imprinted in most tissues, but in the brain, Igf2r is biallelically expressed despite the imprinted Air expression. To investigate the molecular mechanisms of such brain-specific relaxation of Igf2r imprinting, we analyzed its expression and epigenetic modifications in neurons, glial cells and fibroblasts by the use of primary cortical cell cultures. In glial cells and fibroblasts, Igf2r was maternally expressed and Air was paternally expressed, whereas in the primary cultured neurons, Igf2r was biallelically expressed and Air was not expressed. In the differentially methylated region 2 (DMR2), which includes the Air promoter, allele-specific DNA methylation, differential H3 and H4 acetylation and H3K4 and K9 di-methylation were maintained in each cultured cell type. In DMR1, which includes the Igf2r promoter, maternal-allele-specific DNA hypomethylation, histones H3 and H4 acetylation and H3K4 di-methylation were apparent in glial cells and fibroblasts. However, in neurons, biallelic DNA hypomethylation and biallelic histones H3 and H4 acetylation and H3K4 di-methylation were detected. These data indicate that lack of reciprocal imprinting of Igf2r and Air in the brain results from neuron-specific relaxation of Igf2r imprinting associated with neuron-specific histone modifications in DMR1 and lack of Air expression. Our observation of biallelic Igf2r expression with no Air expression in neurons sheds light on the function of Air as a critical effector in Igf2r silencing and suggests that neuron-specific epigenetic modifications related to the lineage determination of neural stem cells play a critical role in controlling imprinting by antisense transcripts.

Animals↗
PubMed2005

Association of polymorphic alleles of CTLA4 with inflammatory bowel disease in the Japanese.

AIM: To examine an association between the cytotoxic T-lymphocyte antigen 4 (CTLA4) gene that plays a role in downregulation of T-cell activation and inflammatory bowel disease consisting of ulcerative colitis (UC) and Crohn's disease (CD) in the Japanese. METHODS: We studied 108 patients with UC, 79 patients with CD, and 200 sex-matched healthy controls, with respect to three single nucleotide polymorphisms (SNPs) in CTLA4, such as C-318T in the promoter region, A+49G in exon 1 and G+6230A in the 3' untranslated region (3'-UTR) by a PCR-restriction fragment length polymorphism method, and to an (AT)(n) repeat polymorphism in 3'-UTR by fragment analysis with fluorescence-labeling on denaturing sequence gels. Frequency of alleles and genotypes and their distribution were compared statistically between patients and controls and among subgroups of patients, using chi (2) and Fisher exact tests. RESULTS: The frequency of "A/A" genotype at the G+6230A SNP site was statistically lower in UC patients than in controls (3.7% vs 11.0%, P = 0.047, odds ratio (OR) = 0.311). Moreover, the frequency of "G/G" genotype at the A+49G SNP site was significantly higher in CD patients with fistula (48.6%) than those without it (26.2%) (P = 0.0388, OR=2.67). CONCLUSION: The results suggest that CTLA4 located at 2q33 is a determinant of UC and responsible for fistula formation in CD in the Japanese.

Adolescent↗
PubMed2005

Novel deletion spanning RCC1-like domain of RPGR in Japanese X-linked retinitis pigmentosa family.

PURPOSE: To describe a macrodeletion spanning entire RCC1-like doman in the RPGR gene in one Japanese family with X-linked retinitis pigmentosa (XLRP). METHODS: Clinical ophthalmologic examinations were performed and genomic DNA was extracted from blood samples. Genomic DNA was analyzed by Southern blot and PCR amplification with specific primers. RESULTS: Patients had severe symptoms with early onset and rapid deterioration. PCR amplification and Southern blot analysis revealed the absence of the 5' half of the RPGR gene. The deletion was confirmed and characterized by designing flanking PCR primers: the deletion start point was located 80 bp upstream of the translation start site in exon 1, the end point was 42 bp downstream of exon 11. CONCLUSIONS: This 30 kb deletion contains the exons coding for the RCC1-like domain of RPGR. It is the first report of a macrodeletion that spans the entire RCC1-like domain of RPGR in X-linked retinitis pigmentosa patients, and suggests that loss of function of this domain disrupts the function of RPGR in human retina.

Adult↗
PubMed2005

Molecular characterization of del(8)(p23.1p23.1) in a case of congenital diaphragmatic hernia.

A 36-week-old fetus was referred to the medical center because of his cystic mass and fluid in left thoracic cavity, and was delivered by cesarean section to manage neonatal problems at 37 weeks of gestation. Emergent surgical repair of the left diaphragmatic hernia was performed, but severe hypoxia persisted, and he expired on the following day. Chromosome analysis of cultured amniotic fluid cells indicated 46,XY,del(8)(p23.1p23.1). This is the fourth case of 8p23.1 deletion associated with diaphragmatic hernia. Microarray comparative genomic hybridization analysis using DNA of cultured amniotic fluid cells showed that six clones were deleted, which were mapped to the region between two low copy repeats (LCRs) at 8p23.1 previously described. Microsatellite analysis revealed that the deletion was of paternal origin, and his parents did not carry 8p23.1 polymorphic inversion. These data strongly suggested that the 8p23.1 interstitial deletion should have arisen through a different mechanism from that of inv dup del(8p) whose structural abnormality is always of maternal origin and accompanies heterozygous 8p23.1 polymorphic inversion in mother.

Adult↗
PubMed2005

Large deletion involving the 5'-UTR in the spastin gene caused mild phenotype of autosomal dominant hereditary spastic paraplegia.

Hereditary spastic paraplegia (HSP) due to mutations in the spastin gene (SPG4) located to 2p22-p21 is the most common form of autosomal dominant (AD) HSP. We performed PCR-based direct sequencing of SPG4, followed by a linkage analysis and subsequent Southern blot analysis in large Japanese kindred where 20 of 33 members were evaluated neurologically, and consequently 6 were affected with HSP. Clinical evaluation showed that the mean age at disease onset of the patients was older and the disability was less severe than those of previously reported typical patients with SPG4 mutations. Direct sequencing of genomic DNA and RT-PCR product did not show a SPG4 mutation despite of a strong linkage to the SPG4 locus at 2p. Southern blot analysis suggested a deletion involving the 5'-UTR of SPG4. Further sequence analysis confirmed a heterozygous 2307-bp deletion spanning from the 5'-UTR to intron 1 of SPG4. The results suggested that transcription of the mutated allele starts from an authentic initiation site, but lacks an authentic translational start site of exon 1 because of a deficient splice donor site and coding region. The abnormal transcripts may result in rapid RNA decay. The novel refractory mutation we identified widens the spectrum of SPG4 mutations. These findings suggest that structural genomic abnormalities of SPG4 are more frequent than expected, and this explains previously reported cases more feasibly in which SPG4 mutations were failed to be identified but the disease was linked to 2p.

5' Flanking Region↗
PubMed2005

Sotos syndrome common deletion is mediated by directly oriented subunits within inverted Sos-REP low-copy repeats.

Sotos syndrome (Sos) is an overgrowth disorder also characterized clinically by mental retardation, specific craniofacial features and advanced bone age. As NSD1 haploinsufficiency was determined in 2002 to be the major cause of Sos, many intragenic mutations and chromosomal microdeletions involving the entire NSD1 gene have been described. In the Japanese population, half of the cases analyzed appear to have a common microdeletion; however, in the European population, deletion cases account for only 9%. Blast analysis of the Sos genomic region on 5q35 revealed two complex mosaic low-copy repeats (LCRs) that are centromeric and telomeric to NSD1. We termed these proximal Sos-REP (Sos-PREP, approximately 390 kb) and distal Sos-REP (Sos-DREP, approximately 429 kb), respectively. On the basis of the analysis of DNA sequence, we determined the size, structure, orientation and extent of sequence identity of these LCRs. We found that Sos-PREP and Sos-DREP are composed of six subunits termed A-F. Each of the homologous subunits, with the exception of one, is located in an inverted orientation and the order of subunits is different between the two Sos-REPs. Only the subunit C' in Sos-DREP is oriented directly with respect to the subunit C in Sos-PREP. These latter C' and C subunits are greater than 99% identical. Using pulsed-field gel electrophoresis analysis in eight Sos patients with a common deletion, we detected an approximately 550 kb junction fragment that we predicted according to the non-allelic homologous recombination (NAHR) mechanism using directly oriented Sos-PREP C and Sos-DREP C' subunits as substrates. This patient specific junction fragment was not present in 51 Japanese and non-Japanese controls. Subsequently, using long-range PCR with restriction enzyme digestion and DNA sequencing, we identified a 2.5 kb unequal crossover hotspot region in six out of nine analyzed Sos patients with the common deletion. Our data are consistent with an NAHR mechanism for generation of the Sos common deletion.

Centromere↗
PubMed2005

Uniparental disomy and imprinting defects in Japanese patients with Angelman syndrome.

We examined 54 patients with deletion-negative Angelman syndrome (AS) using DNA methylation testing and microsatellite polymorphism analysis, and identified three patients with paternal uniparental disomy (UPD) and seven patients with imprinting defects (ID). The three patients with UPD were shown to have paternal isodisomy 15, which we hypothesized to have arisen from duplication of chromosome 15. Two of the patients with ID were siblings and carried microdeletions of the imprinting center (IC), while the remaining five patients had no evidence of deletions and represented sporadic cases. Two of the three patients with UPD and two of the seven patients with ID had not developed seizures. The only patients displaying microcephaly were those with ID who had microdeletions at the IC. These data support the previous findings that indicate that patients with UPD and ID may have a milder phenotype of AS.

Angelman Syndrome↗
PubMed2005

[Protective management for genetic information].

With advances in genomic and genetic medicine, genomic information is being used for the management of disorders. In addition, personalized medicine will be in practice in the near future. Because genetic information, i.e., disease diagnosis, gene mutations, and/or nucleotide sequences, remains unchanged through an individual's life, there are important issues for discussion, such as informed consent at sampling, protection of an individual's genetic information from any social discrimination, handling of samples, and genetic counseling. In this review, how to protect and manage the genetic information at researching and at medical practice, together with several bioethical guidelines regarding such issues, are described. A triangle system in which sample donators, directing physicians/researchers and genetic counselors participate, to manage genetic information appropriately, is also proposed.

Bioethics↗
PubMed2004

Do monochorionic dizygotic twins increase after pregnancy by assisted reproductive technology?

Although monochorionic (MC) dizygotic twins (DZT) are extremely rare in natural pregnancy, six pairs of such twins have successively been reported in a recent short period. All six cases of MC DZT were the products of pregnancy by assisted reproductive technology (ART). In this overview, we summarize these six cases and discuss possible mechanisms of this twinning and clinical implications of confined blood cell chimerism (CBC). The placental MC membrane was diagnosed ultrasonographically in all cases and pathologically in four. The presence of CBC was confirmed in four cases by haplotyping at polymorphic marker loci in peripheral blood leukocytes, karyotyping of lymphocytes and skin fibroblasts, and/or ABO blood group typing. As CBC is attributable to placental vessel anastomosis between DZT, it may become a risk factor for twin-twin transfusion syndrome (TTTS), mortality, and for other complications in twins. MC DZT may produce psychological trauma, especially in a girl/woman when she grows up and is known to be chimeric for a male karyotype and vice versa, although genital organs are generally normal--unlike freemartin in cattle. In addition, CBC in twins may mislead physicians when genotyping for a disease-susceptibility test is performed in medical practice in the near future. Blood group chimera may also cause confusion if a blood transfusion is necessary. Therefore, sufficient informed consent prior to ART and genetic counseling before/after birth are absolutely necessary for improved quality of life. It is most likely that all six cases are the consequence of fusion between two outer cell masses from two zygotes. The ART used in the six MC DZT included in vitro fertilization-embryonic transfer (IVF-ET) into the uterus, FSH-induced superovulation followed by intrauterine insemination, and/or intracytoplasmic sperm injection (ICSI). The use of an ovulation-inducing agent and implantation of several fertilized eggs at close sites are probably the events common among these cases. Assisted hatching, simultaneous ET, the use of eggs that have developed to the blastcyst stage, and cell culture procedures that lead to changes of the nature of cell surface, all may increase the chance of a cell fusion. This "chance hypothesis" can simply explain why MC DZT are very rare in natural pregnancy. Large-scale research on the prevalence of ART-associated MC DZT and long-term follow-up of the twins are essential.

Cell Fusion↗