Biomedical subjects
Hirofumi Ohashi
Publications and source records attributed to Hirofumi Ohashi.
Mild craniosynostosis with 1p36.3 trisomy and 1p36.3 deletion syndrome caused by familial translocation t(Y;1).
We report on a 20-year-old man and a 16-year-old woman with a chromosomal imbalance derived from a balanced translocation, t(Y;1)(q12;p36.3) of the father. The man had a partial trisomy for 1p36.3-pter [46,X,der(Y)t(Y:1)(q12;p36.3)] and mild craniosynostosis of metopic and sagittal sutures as well as a borderline mental impairment, while the woman with a deletion for 1p36.3-pter [46,XX,der(1)t(Y;1)(q12;p36.3)] showed dysmorphic face with large anterior fontanel and severe developmental delay. Fluorescence in situ hybridization (FISH) showed that his trisomy spanned the 5.3-Mb region from 1p telomere harboring the critical region for craniosynostosis. To our knowledge, the man is the first case of a pure type of simple 1p36.3 trisomy as the effect of heterochromatic Yq12-qter deletion likely does not affect phenotype.
Identification of novel RMRP mutations and specific founder haplotypes in Japanese patients with cartilage-hair hypoplasia.
Cartilage-hair hypoplasia (CHH), or metaphyseal dysplasia, McKusick type, is an autosomal recessive disease with diverse clinical manifestations. CHH is caused by mutations in RMRP (ribonuclease mitochondrial RNA processing), the gene encoding the RNA component of the ribonucleoprotein complex RNase MRP. A common founder mutation, 70A>G has been reported in the Finnish and Amish populations. We screened 11 Japanese patients with CHH for RMRP mutations and identified mutations in five probands, including three novel mutations (16-bp dup at +1, 168G>A, and 217C>T). All patients were compound heterozygotes for an insertion or duplication in the promoter or 5'-transcribed regions and a point mutation in the transcribed region. Two recurrent mutations were unique to the Japanese population: a 17-bp duplication at +3 and 218A>G. Haplotype analysis revealed that the two mutations common in Japanese individuals were contained within distinct haplotypes. Through this analysis, we have identified a unique mutation spectrum and founder mutations in the Japanese population.
Comprehensive screening of multiple epiphyseal dysplasia mutations in Japanese population.
Multiple epiphyseal dysplasia (MED) is among the most genetically heterogeneous skeletal dysplasias. Six genes involved in MED, COMP, MATN3, COL9A1, COL9A2, COL9A3, and DTDST have been identified; however, the presence of additional disease genes has been reported, and the detection rate for mutations in known genes accounts for no more than 50% of patients with MED in Western populations. Here, we screened the six known disease genes in 35 consecutive Japanese MED patients. We analyzed the entire coding region of each gene, along with flanking intron-exon junctions, by direct sequencing. A total of 19 mutations were identified in COMP, MATN3, COL9A2, COL9A3, and DTDST. The detection rate for known mutations was higher in this study than in previous reports, and we identified a substantially different spectrum of mutations. Mutations in MATN3 were more prevalent among these Japanese patients, whereas no DTDST mutations were detected. Most of the mutations were localized within specific regions of each gene: COMP mutations were found in the calmodulin-like repeat domains; MATN3 mutations in the von Willebrand factor type A domain; and type IX collagen gene mutations occurred in the third collagenous domains. Based on the integration of clinical and genetic information, we propose an algorithm for detecting mutations in Japanese MED patients. Our study further supports the existence of additional MED gene(s).
Germline KRAS and BRAF mutations in cardio-facio-cutaneous syndrome.
Cardio-facio-cutaneous (CFC) syndrome is characterized by a distinctive facial appearance, heart defects and mental retardation. It phenotypically overlaps with Noonan and Costello syndrome, which are caused by mutations in PTPN11 and HRAS, respectively. In 43 individuals with CFC, we identified two heterozygous KRAS mutations in three individuals and eight BRAF mutations in 16 individuals, suggesting that dysregulation of the RAS-RAF-ERK pathway is a common molecular basis for the three related disorders.
No detectable genomic aberrations by BAC array CGH in Kabuki make-up syndrome patients.
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Intrafamilial phenotypic diversity in multiple epiphyseal dysplasia associated with a COL9A2 mutation (EDM2).
We describe a Japanese family with an autosomal dominant multiple epiphyseal dysplasia (MED EDM2) showing significant phenotypic diversity among the five affected members. Genomic analysis for COL9A2 identified an Ex3-1A>G heterozygous mutation, which has been proved to result in skipping of exon 3. The proband was a 9-year-old boy, who presented with ulnar club hands due to severe epiphyseal dysplasia in the distal ulnae. Radiological examination showed multiple epiphyseal dysplasias, predominantly involving the knee and the wrist. The hip appeared almost normal. The malalignment of the wrist was successfully treated with a limb lengthening procedure. The phenotype of the asymptomatic 12-year-old brother was similar to, but milder than, that of the proband. The asymptomatic 39-year-old mother, the 35-year-old uncle, and the 65-year-old grandmother with bilateral painful knees showed radiographically mild and severe osteoarthritis of the knee, respectively, and none of them had wrist deformity.
Taste after reduction of the tongue in Beckwith-Wiedemann syndrome.
We tested the sensitivity of taste after reduction of the tongue in four girls with Beckwith-Wiedemann syndrome. No patient had taste blindness, but the ability to detect salty and bitter tastes declined after reduction of the tongue.
A type II collagen mutation also results in oto-spondylo-megaepiphyseal dysplasia.
Oto-spondylo-megaepiphyseal dysplasia (OSMED) is a skeletal dysplasia characterized by severe sensorineural hearing loss, enlarged epiphyses and early onset of osteoarthritis. COL11A2 has been reported as a causative gene for OSMED. We have identified a novel COL2A1 mutation at a splice-acceptor site within intron 10 (c.709-2A>G) in an OSMED patient. This mutation caused the skipping of exon 11, and of exons 11 and 13. These exon-skipping events are presumed to cause an in-frame deletion of the triple helical region of the COL2A1 product. Thus, our findings highlight the genetic heterogeneity of OSMED and extend the phenotypic spectrum of type II collagenopathy, as well as confirming the overlap between type II and type XI collagenopathies.
Ehlers-Danlos syndrome type VIB with characteristic facies, decreased curvatures of the spinal column, and joint contractures in two unrelated girls.
Two unrelated girls, aged 11 and 14 years, with clinical manifestations of Ehlers-Danlos syndrome (EDS) type VIB, characteristic facies, skeletal abnormalities, and other features are described. They had Marfanoid habitus with pectus excavatum; fragile, hyperextensible, and readily bruisable skin with widened, atrophic scars; recurrent hematomas; generalized joint laxity; hypotonia; scoliosis; and mild delay of gross motor development. Lysyl hydroxylase deficiency was ruled out in Patient 1. Parental consanguinity was present in Patient 2. They both had, in early childhood, down-slanting palpebral fissures, drooping lower eyelids, short nose, small mouth, and long philtrum. Facial features that persisted included thick eyebrows, hypertelorism, strabismus, blue sclerae, low-set, and slanted ears, hypoplastic columella, high-arched palate, and thin upper lip. They had tubular stenosis of the phalanges, metacarpals, and metatarsals; decreased physiological curvatures of the spinal column with tall vertebrae; and joint contractures including talipes equinovarus and progressive talipes valgus. Their hearing of high-pitched sounds was impaired. They had constipation and recurrent cystitis with an enlarged bladder. In view of these findings, we propose that these two girls represent a clinically recognizable subgroup of EDS type VIB.
Germline mutations in HRAS proto-oncogene cause Costello syndrome.
Costello syndrome is a multiple congenital anomaly and mental retardation syndrome characterized by coarse face, loose skin, cardiomyopathy and predisposition to tumors. We identified four heterozygous de novo mutations of HRAS in 12 of 13 affected individuals, all of which were previously reported as somatic and oncogenic mutations in various tumors. Our observations suggest that germline mutations in HRAS perturb human development and increase susceptibility to tumors.
Functional analysis of PTPN11/SHP-2 mutants identified in Noonan syndrome and childhood leukemia.
Noonan syndrome (NS) is characterized by short stature, characteristic facial features, and heart defects. Recently, missense mutations of PTPN11, the gene encoding protein tyrosine phosphatase (PTP) SHP-2, were identified in patients with NS. Further, somatic mutations in PTPN11 were detected in childhood leukemia. Recent studies showed that the phosphatase activities of five mutations identified in NS and juvenile myelomonocytic leukemia (JMML) were increased. However, the functional properties of the other mutations remain unidentified. In this study, in order to clarify the differences between the mutations identified in NS and leukemia, we examined the phosphatase activity of 14 mutants of SHP-2. We identified nine mutations, including a novel F71I mutation, in 16 of 41 NS patients and two mutations, including a novel G503V mutation, in three of 29 patients with leukemia. Immune complex phosphatase assays of individual mutants transfected in COS7 cells showed that ten mutants identified in NS and four mutants in leukemia showed 1.4-fold to 12.7-fold increased activation compared with wild-type SHP-2. These results suggest that the pathogenesis of NS and leukemia is associated with enhanced phosphatase activity of mutant SHP-2. A comparison of the phosphatase activity in each mutant and a review of previously reported cases showed that high phosphatase activity observed in mutations at codons 61, 71, 72, and 76 was significantly associated with leukemogenesis.
Double-layered patella in multiple epiphyseal dysplasia is not exclusive to DTDST mutation.
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Novel COL9A3 mutation in a family with multiple epiphyseal dysplasia.
Multiple epiphyseal dysplasia (MED) is a common skeletal dysplasia characterized by mild to moderate short stature, early-onset of osteoarthritis (OA) mainly in the hip and knee joints, and abnormally small and/or irregular epiphyses. MED is clinically and genetically heterogeneous. Six causative genes of MED have been reported, including type IX collagen genes (COL9A1, COL9A2, COL9A3). All the type IX collagen mutations previously reported cause exon skipping that loses the COL3 domain. Here we have identified a novel COL9A3 mutation co-segregating in a three-generation family with MED. The mutation (IVS3 + 5G > A) was speculated to lose the COL3 domain by skipping of exon 3, which was confirmed by in vitro analysis. The patients were of normal height and had minimal complaints with phenotypes being more severe in male patients. The radiographic phenotypes of the patients were relatively milder than those of previously reported cases, and were indistinguishable to common, idiopathic OA.
Novel and recurrent exon 13 mutations of COMP in pseudoachondroplasia.
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The phenotypic spectrum of COL2A1 mutations.
Heterozygous mutations of COL2A1 create several clinical entities collectively termed type II collagenopathies. These disorders not only impair skeletal growth but also cause ocular and otolaryngological abnormalities. The classical phenotypes include the spondyloepiphyseal dysplasia (SED) spectrum with variable severity, Stickler dysplasia type I (STD-I), and Kniest dysplasia (KND). Most COL2A1 mutations occur in the triple helical region of alpha 1(II) chains: the SED spectrum is mostly attributed to missense mutations that substitute bulky amino acids for glycine residues, STD-I to haploinsufficiency of truncation mutations, and KND to exon skipping due to splice-site mutations. To further elucidate the genotype-phenotype relationship of type II collagenopathies, we examined COL2A1 mutations in 56 families that were suspected of having type II collagenopathies, and found 38 mutations in 41 families. Phenotypes for all 22 missense mutations and one in-frame deletion in the triple helical region fell along the SED spectrum. Glycine to serine substitutions resulted in alternating zones that produce severer and milder skeletal phenotypes. Glycine to nonserine residue substitutions exclusively created more severe phenotypes. The gradient of the SED spectrum did not necessarily correlate with the occurrence of extraskeletal manifestations. All nine truncation or splice-site mutations in the triple helical or N-propeptide region caused STD-I or KND, and extraskeletal changes were inevitable in both phenotypes. All six C-propeptide mutations produced a range of atypical skeletal phenotypes and created ocular, but not otolaryngological, changes.
Deletion involving the TWIST locus and the HOXA cluster: a contiguous gene syndrome on 7p?
Deletion of TWIST on 7p21 leads to Saethre-Chotzen syndrome, whereas deletion of the HOXA cluster on 7p15.2 leads to hand-foot-genital syndrome. We report here a patient with 46,XY,del(7)(p15.2p21) who had craniosynostosis, maxillary hypoplasia, prominent ear crus, rectoperineal fistula, and hypoplastic fifth fingers. Using fluorescence in situ hybridization, we demonstrated the deletion to encompass the TWIST locus and the HOXA cluster. We suggest that many, if not all, of the features of this patient could be accounted for by combined haploinsufficiency of the TWIST and HOXA cluster. Hence, the patient's phenotype may define a new contiguous gene syndrome on 7p.