A Novel RUNX2 Mutation in a Korean Family with Cleidocranial Dysplasia / 대한소아치과학회지

Cleidocranial dysplasia (CCD) is an autosomal-dominant disease characterized by the delayed closure of cranial sutures, defects in clavicle formation, supernumerary teeth, and delayed tooth eruption. Defects in the Runt-related transcription factor 2 (RUNX2), a master regulator of bone formation, have been identified in CCD patients. The aim of this study was to identify the molecular genetic causes in a CCD family with delayed tooth eruption.The 23-year-old female proband and her mother underwent clinical and radiographic examinations, and all coding exons of the RUNX2 were sequenced. Mutational analysis revealed a single nucleotide deletion mutation (NM_001024630.4 : c.357delC) in exon 3 in the proband and her mother. The single C deletion would result in a frameshift in translation and introduce a premature stop codon [p.(Asn120Thrfs*24)]. This would result in the impaired function of RUNX2 protein, which may be the cause of delayed eruption of permanent teeth in the family.

Autosomal recessive osteopetrosis type I: description of pathogenic variant of TCIRG1 gene / Osteopetrosis infantil maligna: descripción de una nueva mutación patogénica de TCIRG1

Abstract Background: Autosomal malignant osteopetrosis is a rare condition arising from dysfunction of bone-resorbing osteoclasts, in which diagnosis requires a high suspicion index. Treatment of choice is allogeneic stem cell transplantation. Best outcomes occur if the procedure is carried out before damage to cranial nerves ensues; nonetheless, patients improve their clinical condition. Case report: An 8-month-old infant was referred for hematology consultation for cytopenias, hepatomegaly, and growth failure. Autosomal malignant osteopetrosis was diagnosed on the basis of physical findings, alteration in calcium and phosphorus metabolism, and hyperdensity of bone. DNA was obtained from the patient and parents; compound heterozygosity of the TCIRG1 gene with a previously non-described deletion (c.1809_1818del) was identified. Conclusions: A new pathogenic mutation of TCIRG1 was identified in a Mexican osteopetrotic patient. Hematopoietic stem cell transplantation was offered as the best available treatment but declined by the parents. An early recognition and wider access to this procedure should be implemented.

Resumen Introducción: La osteopetrosis infantil maligna es una condición rara cuyo origen es la deficiente reabsorción ósea por parte de los osteoclastos. Su diagnóstico requiere un alto índice de sospecha. El tratamiento de elección es el trasplante alogénico de células hematopoyéticas. Los mejores desenlaces ocurren si el procedimiento se lleva a cabo antes de que ocurra daño a los nervios craneales. Caso clínico: Paciente masculino de 8 meses de edad fue referido a la consulta de hematología por citopenias, hepatomegalia y falla para crecer. Se diagnosticó osteopetrosis infantil maligna basándose en los hallazgos de la exploración física, la alteración del metabolismo del calcio y el fósforo y la hiperdensidad del hueso. Se obtuvo ADN del paciente y ambos padres; se demostró un heterocigosidad compuesta del gen TCIRG1 con una deleción (c.1809_1818del) no descrita previamente. Conclusiones: Una nueva mutación patogénica de TCIRG1 se identificó en un paciente mexicano con osteopetrosis. Se ofreció trasplante de células progenitoras hematopoyéticas como el mejor tratamiento disponible, pero fue rechazado por los padres. Se necesita un reconocimiento temprano y la implementación del acceso generalizado a este procedimiento.

Investigation of the GJB6 Deletion Mutations Del (GJB6-D13s1830) and Del (GJB6-D13s1854) in Iranian Patients with Autosomal-Recessive Non-Syndromic Hearing Loss (ARNSHL)

Hearing loss (HL) is the most common inherited sensory disorder affecting about 1 in 1000 births. The first locus for nonsyndromic autosomal recessive HL is on chromosome 13q11-22. The two genes, GJB2 and GJB6, are closely located on chromosome and are known to be co-expressed in the embryonic cochlea. Deletion mutations involving GJB6 were associated with autosomal-recessive nonsyndromic hearing loss (ARNSHL) and in combination with a GJB2 mutation with digenic ARNSHL. The objective of this study was to screen for the del (GJB6-D13S1830) and del (GJB6-D13s1854) mutations in GJB6 gene in patients with ARNSHL from Iran, using multiplex PCR and direct sequencing methods. Agarose gel electrophoresis and DNA sequencing of amplified fragment of the PCR reaction showed none of the patients was found to carry deletion in GJB6 gene which indicates that these deletions are restricted to certain populations and indicating a founder effect regarding these deletions.

An unusual and novel heterozygous TCIRG1 mutation causes infantile ma-lignant osteopetrosis / 中国病理生理杂志

[ ABSTRACT] AIM: To investigate the underlying genetic changes of a Chinese patient with infantile malignant osteopetrosis ( IMO) .IMO is a monogenic disease, mostly caused by mutations of TCIRG1 and CLCN7 genes.The former is believed a homozygous gene and only cause the disease in homozygous or compound heterozygous status.However, it has been reported that heterozygous mutations also cause the disease in 6 non-Chinese cases.METHODS:Genomic DNA was extracted from peripheral blood of the patient and his parents.All exons and splice sites of TCIRG1 and CLCN7 genes were amplified by PCR followed by Sanger sequencing.Mutation detection in the 2 genes was also investigated in the parents. Haplotypes were constructed by variations obtained in mutation detection and microsatillites flanking TCIRG1 gene in the family by Cyrillic.Chromosomal microarray analysis ( CMA) was performed to detect copy number variations ( CNV) of the patient and his mother.RESULTS:A novel mutation c.449_452delAGAG ( p.Gln149Glnfs16) was detected in the pa-tient.This mutation truncated 666 amino acids at the C terminal of the V-ATPase 116 kD isoform a3 protein.It wiped out the entire ATPase V0 complex and was predicted to result in total loss of protein function.This mutation was also detected in the patient’ s father.No pathogenic mutation was detected in CLCN7 gene.CMA did not reveal any CNV involving TCIRG1 or CLCN7 gene.CONCLUSION:We reported a novel heterozygous mutation of TCIRG1 gene causing IMO.This represents the first IMO case in China caused by heterozygous TCIRG1 gene mutation.

Mitochondrial DNA 4977bp Deletion Mutation in Peripheral Blood Reflects Atrial Remodeling in Patients with Non-Valvular Atrial Fibrillation

PURPOSE: Recently, mitochondrial DNA 4977bp deletion (mtDNA4977-mut), a somatic mutation related to oxidative stress, has been shown to be associated with atrial fibrillation (AF). We hypothesized that patient age, as well as electroanatomical characteristics of fibrillating left atrial (LA), vary depending on the presence of mtDNA4977-mut in peripheral blood among patients with non-valvular AF. MATERIALS AND METHODS: Analyzing clinical and electroanatomical characteristics, we investigated the presence of the mtDNA4977-mut in peripheral blood of 212 patients (51.1+/-13.2 years old, 83.5% male) undergoing catheter ablation for non-valvular AF, as well as 212 age-matched control subjects. RESULTS: The overall frequency of peripheral blood mtDNA4977-mut in patients with AF and controls was not significantly different (24.5% vs. 19.3%, p=0.197). When the AF patient group was stratified according to age, mtDNA4977-mut was more common (47.4% vs. 20.0%, p=0.019) in AF patients older than 65 years than their age-matched controls. Among AF patients, those with mtDNA4977-mut were older (58.1+/-11.9 years old vs. 48.8+/-11.9 years old, p<0.001). AF patients positive for the mtDNA mutation had greater LA dimension (p=0.014), higher mitral inflow peak velocity (E)/diastolic mitral annular velocity (Em) ratio (p<0.001), as well as lower endocardial voltage (p=0.035), and slower conduction velocity (p=0.048) in the posterior LA than those without the mutation. In multivariate analysis, E/Em ratio was found to be significantly associated with the presence of mtDNA4977-mut in peripheral blood. CONCLUSION: mtDNA4977-mut, an age-related somatic mutation detected in the peripheral blood, is associated with advanced age and electro-anatomical remodeling of the atrium in non-valvular AF.

RUNX2 mutations in Taiwanese patients with cleidocranial dysplasia

Cleidocranial dysplasia (CCD) is an autosomal dominant human skeletal disorder comprising hypoplastic clavicles, wide cranial sutures, supernumerary teeth, short stature, and other skeletal abnormalities. It is known that mutations in the human RUNX2 gene mapped at 6p21 are responsible for CCD. We analyzed the mutation patterns of the RUNX2 gene by direct sequencing in six Taiwanese index cases with typical CCD. One of the patients was a familial case and the others were sporadic cases. Sequencing identified four mutations. Three were caused by single nucleotide substitutions, which created a nonsense (p.R391X), two were missense mutations (p.R190W, p.R225Q), and the forth was a novel mutation (c.1119delC), a one-base deletion. Real time quantitative PCR adapted to determine copy numbers of the promoter, all exons and the 3'UTR region of the RUNX2 gene detected the deletion of a single allele in a sporadic case. The results extend the spectrum of RUNX2 mutations in CCD patients and indicate that complete deletions of the RUNX2 gene should be considered in those CCD patients lacking a point mutation detected by direct sequencing.

The role of NF-κB binding element in regulation of NOD2 gene / 中华微生物学和免疫学杂志

Objective To investigate the role of NF-KB binding element in regulation of NOD2. Methods Promoter region of NOD2 containing the NF-κB binding site was amplified by PCR from human genome DNA and correctly connected to the vector pEGFP-N3 which had been cut out promoter by restriction enzyme to obtain the GFP expression vector driven by human NOD2 gene promoter. The constructed plasmids were transiently transferred into cell line HeLa by LipofectAMINETM2000 and the GFP expression was ob- served by the inversion fluorescence microscope. The NF-κB binding site in the constructed vector pEGFP- N3-NOD2wt was deleted by the QuikChange site-directed mutagenesis kit. The recombinant plasmid mpEG- FP-N3-NOD2 was transiently transferred into cell line HeLa by LipofectAMINETM2000, and the GFP expres- sion was observed by the inversion fluorescence microscope. Results The constructed pEGFP-N3-NOD2wt plasmids and mpEGFP-N3-NOD2 were the same as the design confirmed by restriction digestion and se- quence analysis. The results of the cell transient transfection indicated that different strength of GEP ex- pressed by recombinant plasmids in HeLa cells could be observed. The GFP expression of constructed mpEGFP-N3-NOD2 was lower than that of pEGFP-N3-NOD2wt. Conclusion The GFP expression vector driven by human NOD2 gene promoter which contains the NF-κB binding site, and the site deleted plasmid were successfully constructed. The GFP expression of recombinant plasmid mpEGFP-N3-NOD2, deletion of the NF-KB binding site, was obviously weaken in HeLa. The results indicate that NF-KB binding element may play a positive role in regulation of NOD2 gene, which establishes favourable bases for further study on the mechanism of NOD2 gene expression and regulation.

Less DeltamtDNA4977 than normal in various types of tumors suggests that cancer cells are essentially free of this mutation

Levels of mtDNA(4977) deletions (DeltamtDNA(4977)) have been found to be lower in tumors than in adjacent non-tumoral tissues. In 87 cancer patients, DeltamtDNA(4977) was detected by multiplex polymerase chain reaction (PCR) amplification in 43 (49%) of the tumors and in 74 (85%) of the samples of non-tumoral tissues that were adjacent to the tumors. DeltamtDNA(4977) deletions were detected in 24% of the breast tumors, 52% of the colorectal tumors, 79% of the gastric tumors, and 40% of the head and neck tumors as compared with 77, 83, 100, and 90% of the adjacent respective non-tumoral tissues at the same DNA template dilution. Based on limiting dilution PCR of 16 tumors and their adjacent non-tumoral tissues, it was found that the amount of DeltamtDNA(4977) was 10- to 100-fold lower in the tumor than in the respective control non-tumoral tissues. Real-time PCR experiments were performed to quantify the number of DeltamtDNA(4977) deletions per cell, by determining the mitochondrial-to-nuclear DNA ratio. In all of the cases of breast, colorectal, gastric, and head and neck cancer the proportion of DeltamtDNA(4977) in tumors was lower than that of the respective non-tumoral tissue. Traces of DeltamtDNA(4977) in tumors were apparently due to contamination of tumor tissue with surrounding non-tumoral tissue, as evidenced by tumor microdissection and in situ PCR techniques, suggesting that tumors are essentially free of this mutation. Although the metabolic effect of DeltamtDNA(4977) may be minimal in normal (non-tumor) tissue, in tissue under stress, such as in tumors, even low levels of DeltamtDNA(4977) deletions may be intolerable.

Gene cloning and expression of human chemokine ELC / 第三军医大学学报

Objective To clone human chemokine ELC and express the ELC fusion protein. Methods Total RNA from human inflammatory tonsil was extracted and the cDNA was generated with reverse transcription. Mature ELC gene was amplified with PCR and NcoⅠand EcoRⅠ sites were added to the 5′ and 3′ terminal respectively, and then cloned into pET32a(+). E.coli DH5? was transformed with the recombinant plasmid, and positive clones were selected. The inserted DNA was verified by enzyme digestion and DNA sequencing. The fusion expression vector of mature ELC was formed with deletion mutation. ELC expression was analyzed by SDS-PAGE and Western blotting and the ELC fusion protein was purified. Results Human chemokine ELC was successfully cloned and the fusion protein was expressed and purified. Conclusion The ELC fusion protein was expressed with solubility.

Characterization of yeast deoxyhypusine synthase: PKC-dependent phosphorylation in vitro and functional domain identification

The biosynthesis of hypusine [Nepsilon-(4-amino-2-hydroxybutyl)-lysine] occurs in the eIF-5A precursor protein through two step posttranslational modification involving deoxyhypusine synthase which catalyzes transfer of the butylamine moiety of spermidine to the epsilon-amino group of a designated lysine residue and subsequent hydroxylation of this intermediate. This enzyme is exclusively required for cell viability and growth of yeast (Park, M.H. et al., J. Biol. Chem. 273: 1677-1683, 1998). In an effort to understand structure-function relationship of deoxyhypusine synthase, posttranslational modification(s) of the enzyme by protein kinases were carried out for a possible cellular modulation of this enzyme. And also twelve deletion mutants were constructed, expressed in E. coli system, and enzyme activities were examined. The results showed that deoxyhypusine synthase was phosphorylated by PKC in vitro but not by p56lck and p60c-src. Treatment with PMA specifically increased the relative phosphorylation of the enzyme supporting PKC was involved. Phosphoamino acid analysis of this enzyme revealed that deoxyhypusine synthase is mostly phosphorylated on serine residue and weakly on threonine. Removal of Met1-Glu10 (deltaMet1-Glu10) residues from amino terminal showed no effect on the catalytic activity but further deletion (deltaMet1-Ser20) caused loss of enzyme activity. The enzyme with internal deletion, deltaGln197-Asn212 (residues not present in the human enzyme) was found to be inactive. Removal of 5 residues from carboxyl terminal, deltaLys383-Asn387, retained only slight activity. These results suggested that deoxyhypusine synthase is substrate for PKC dependent phosphorylation and requires most of the polypeptide chains for enzyme activity except the first 15 residues of N-terminal despite of N- and C-terminal residues of the enzyme consist of variable regions. Copyright 2000 Academic Press.

Molecular Genetic Studies on the Human CYP21A2 Gene (1) / 대한내분비학회지

Congenital adrenal hyperplasia, especially due to steroid-12-hydroxylase(P450c21) deficiency, is one of the most common autosomal recessive inborn errors at adrenal steroidogenesis in Korean. Molecular genetic analysis has demonstrated that there are two steroid 21-hydroxylase genes, CYP21A1P and CYP21A2. The CYP21A2 gene encodes P450c21, whereas the CYP21A1P gene is a pseudogene. Since there is 98 percent homology between the CYP21A1P and CYP21A2 gene in nucleotide sequences, it has hampered the characterization of molecular defects in the CYP21A2 gene.In this study, efforts have been made to selectively PCR amplify the CYP21A2 gene and test feasibility of DNA microextraction from Guthrie card for prospective use of molecular screening. This study was also aimed at investigating deletion mutations in P450c21 deficient patients, as well as allele frequencies and average heterozygosity of exon 1 A/C polymorphism in Korean newborns. Genomic DNAs were obtained from Guthrie cards of 50 Korean newborns by microextraction method and these DNAs were analyzed by PCR-allele specific oligonucleotide(ASO) hybridization. First part of the CYP21A2 gene has been successfully amplified and digested by restriction enzyme using Taq I or Kpn I, subsequently run on 1.5% agarose gel to confirm its specificity. The anterior 1141 bp PCR product was utilized to examine the frequency and average heterozygosity of exon 1 A/C polymorphism in 100 alleles by ASO dot blot hybridization. Amplified genomic DNAs from four P450c21 deficient patients out of three families were screened by PCR to see if any one has complete deletion of the CYP21A2 gene.The results were as follows;1) The average 1230ng of genomic DNA was obtained form single semi-circled Guthrie card of 1/2 inch diameter by microextraction method, which has been successfully used for DNA analysis.2) The PCR amplified anterior 1141 bp product from the CYP21A2 gene was digested by Kpn I, generating 309 bp, 832 bp fragments, not by Taq I, indicating its specificity.3) The frequencies of exon 1 nucleotide 138 A/C polymorphism in Korean population were 0.81, 0.91 respectively, and average heterozygosity was 0.31.4) None of four P450c21 deficient patients turned out to carry complete deletion of the CYP21A2 gene based on selective PCR amplification of the CYP21A2 gene.In conclusion, dried blood spots from Guthrie card can be sued for DNA analysis because of easy sample collection, bandling, shipment, and DNA extraction feasibility. The selective PCR amplification of the CYP 21A2 gene will pave the way for molecular characterization in P450c21 deficient patients. The exon 1 A/C polymorphism can by efficiently used for molecular diagnosis of P450c21 deficiency in informative families, though it has a drawback of handling radioactive material.