The mitochondrial DNA A3243G mutation in Werner's syndrome

OBJECTIVE: The contribution of the A3243G mutation in mitochondria DNA (mtDNA) to diabetes mellitus (DM) in Werner's syndrome (WS) was studied. PATIENTS AND METHOD: DNA samples from peripheral white blood cells (WBCs) originating from 24 Japanese WS patients aged 30-56 were used. For control, 239 subjects aged 15-95 were also used. The mtDNA was amplified using specific primers. After HaeIII digestion, the ratio of the A3243G mutation was compared. RESULTS: The ratio of the A3243G mutation is 0.45+/-0.13% in WS, which is statistically insignificant from those in the control groups at various age. The mutation types of WRN in genomic DNA did not affect the ratio of the A3243G mtDNA mutation. No significant difference was observed concerning to the ratios among the WS patients with and without DM, and also controls. Furthermore, no significant difference was observed in the ratios of A3243G mutation among controls from various age groups. CONCLUSION: The A3243G mutation in mtDNA does not accumulated in WBCs from WS. Mitochondria A3243G mutation may not contribute to the pathogenesis of DM observed in WS.     

A20 inactivation in ocular adnexal MALT lymphoma

Recent studies showed A20 inactivation by deletion, mutation and promoter methylation in ocular adnexal mucosa-associated lymphoid tissue lymphoma. However, the incidences of A20 abnormalities and their clinical impact remain for the most part unknown. It is also unknown whether ABIN-1 and ABIN-2, the components of the A20 NF-κB inhibitor complex, are inactivated by genetic changes in ocular adnexal mucosa-associated lymphoid tissue lymphoma. A total of 105 cases were investigated for A20 mutation/deletion, ABIN-1/2 mutation, MALT1 and IGH involved translocation. Somatic mutation was seen frequently in A20 (28.6%) but rarely in ABIN-1 (1%) and ABIN-2 (1%). A20 mutations were significantly associated with A20 heterozygous deletion, and both were mutually exclusive from the MALT1 or IGH involved translocations. A20 mutation/deletion was also significantly associated with increased expression of the NF-κB target genes CCR2, TLR6 and BCL2. The cases with A20 mutation/deletion required significantly higher radiation dosages to achieve complete remission than those without these abnormalities.     

Role of UGT1A1 mutation in fasting hyperbilirubinemia

BACKGROUND AND AIM: Low-grade fasting hyperbilirubinemia is a common observation in healthy subjects (HS), whereas high-grade fasting hyperbilirubinemia is believed to be a characteristic finding of Gilbert's syndrome. This study was undertaken to assess the role of mutation in bilirubin UDP- glycosyltransferase gene (UGT1A1) on fasting hyperbilirubinemia. METHODS: Analysis of UGT1A1 and a caloric restriction test (400 kcal for 24 h) were performed in 56 healthy subjects (25 males, 31 females), and 28 patients with Gilbert's syndrome (18 males, 10 females). There were 29 healthy subjects with no mutation in UGT1A1, and 27 healthy subjects and 26 Gilbert's syndrome patients with mutations in the coding and/or promoter (TATA box) regions of UGT1A1. RESULTS: The mean increment of serum bilirubin (DeltaSB) was 7.6 micromol/L [corrected] (males) and 4.1 micromol/L (females) in subjects with no UGT1A1 mutation. Subjects with mutation in UGT1A1 showed higher levels of DeltaSB than individuals without mutation. Among healthy subjects, gender difference in DeltaSB values was observed only in individuals with the wild type of UGT1A1, but not in those with mutations in this gene. CONCLUSION: The results of the present study suggest that UGT1A1 mutation has a role in the development of high-grade fasting hyperbilirubinemia after caloric restriction.     

国人SCN5A基因新的同义突变位点

目的:研究中国人心原性猝死相关基因SCN5A突变位点.方法:采用聚合酶链反应和DNA测序对1例RQT间期综合征(LQTs)和2例特发性J波患者SCN5A基因进行突变检测.结果:①3例患者在国内、外已知的SCN5A突变位点上,均未发现有突变.②发现1个新的同义突变(T990C),位于钠通道α-亚基的DⅠ区段S5～S6胞外环上.结论:这个新的同义突变可能通过影响门控性钠通道的跨膜电流而与恶性心律失常的发生相关.     

Factor V Leiden G1691A, prothrombin G20210A, and MTHFR C677T mutations in Turkish inflammatory bowel disease patients

BACKGROUND/AIMS: Patients with inflammatory bowel disease (IBD) have an increased risk for thromboembolic complications. We investigated the incidence of factor V Leiden G1691A, methylene tetrahydrofolate reductase (MTHFR) C677T, and prothrombin G20210A mutation in 27 Turkish IBD patients with no history of thromboembolic disease. METHODOLOGY: Twenty-seven patients, 22 with ulcerative colitis (UC) and 5 with Crohn's disease (CD), and 47 healthy were included to the study. The DNAs were obtained from peripheral blood by using pure polymerase chain kit. Then, factor V Leiden G1691A, which active protein C resistance positive, prothrombin G20210A and MTHFR C677T mutations were investigated in DNA by using LightCycler-Factor V Leiden G1691A mutation, Prothrombin G20210A and MTHFR C677T estimate kits. RESULTS: The heterozygote factor V Leiden G1691A mutation was detected in 3 (11.1%) patients with IBD and 2 (4.3%) controls (p > 0.05). The homozygote factor V Leiden G1691A mutation was not estimated among patients and controls. Heterozygote prothrombin G20210A mutation was detected in 2 (7.4%) patients with IBD and in 0 (0%) controls (p > 0.05). There was no homozygote prothrombin G20210A mutation in IBD and controls. Heterozygote MTHFR C677T mutation was 10 of 27 (37%) patients with IBD while 15 of 47 (32%) controls (p > 0.05). Homozygote MTHFR C677T mutation was detected in 4 patients (14.9%) with IBD and 3 (6.3%) controls (p > 0.05). CONCLUSIONS: Our study did not reveal any association between IBD and the most common hereditary thrombophilic factors and these mutations interfere with neither disease manifestations nor the thrombotic complications.     

BRAF T1796A transversion mutation in various thyroid neoplasms

A high prevalence of activating mutation of the B type Raf kinase (BRAF) gene was recently reported in papillary thyroid cancer (PTC). However, the frequency of this mutation in several other types of thyroid neoplasms was not thoroughly investigated. In the present study, in addition to PTC, we evaluated various thyroid tumor types for the most common BRAF T1796A mutation by direct genomic DNA sequencing. We found a high and similar frequency (45%) of the BRAF T1796A mutation in two geographically distinct PTC patient populations: one composed of sporadic cases from North America, and the other from Kiev, Ukraine, that included individuals who were exposed to the Chernobyl nuclear accident. In contrast, we found BRAF mutation in only 20% of anaplastic thyroid cancers and no mutation in medullary thyroid cancers and benign thyroid hyperplasia. We also confirmed previous reports that the BRAF T1796A mutation did not occur in benign thyroid adenomas and follicular thyroid cancers. Specific analysis of the Ukraine patients with confirmed history of radiation exposure failed to show a higher incidence of BRAF mutation. Our results suggest that frequent occurrence of BRAF mutation is inherently associated with PTC, irrespective of geographic origin, and is apparently not a radiation-susceptible mutation. The lack or low prevalence of BRAF mutation in other thyroid neoplasms is consistent with the notion that other previously defined genetic alterations on the same signaling pathway are sufficient to cause tumorigenesis in most thyroid neoplasms.     

A D255H substitution in the arylsulphatase A gene of two unrelated Belgian patients with late-infantile metachromatic leukodystrophy

Summary Metachromatic leukodystrophy (MLD) is an autosomal recessive disease of myelin metabolism caused by a deficiency in the lysosomal enzyme arylsulphatase A (ARSA). We have identified a new mutation in exon 4 of the ARSA gene of two unrelated Belgian patients with late-infantile MLD. The mutation predicts an aspartic acid-to-histidine substitution at position 255 in arylsulphatase A (D255H), in a highly conserved region among sulphatases. Transient expression of the mutation in COS cells did not show an increase in ARSA activity. Both patients were compound heterozygotes carrying the frequent splice site mutation in intron 2 (459+1GA) on the other allele.     

Gilbert综合征和Crigler-Najjar综合征相关尿苷二磷酸葡糖醛酸转移酶A1基因突变位点特征分析

目的探讨Gilbert综合征(GS)和Crigler-Najjar综合征(CNS)相关尿苷二磷酸葡糖醛酸转移酶A1(UGT1A1)基因的突变特征及与临床的相关性。方法通过检索PubMed和人类基因突变数据库归纳UGT1A1基因突变位点的特征并分析其临床相关性。结果截至2018年11月16日,共发现UGT1A1基因163个突变位点,上述位点存在以下规律:(1)GS或CNS表型相关的UGT1A1的不同外显子发生的基因突变个数,均与外显子长度呈正相关;(2)无义点突变主要发生在CNS I型;(3)GS、CNS II型的复合杂合突变位点的组合和分布存在一定规律,其中GS的4种复合杂合组成中,均有-3279T>G突变;(4)亚洲地区报道的UGT1A1基因突变位点在c.211-c.558有明显的聚集性。结论UGT1A1基因突变位点不同、报道地区不同及人群不同,其突变特征及临床相关性也不同。本研究对GS和CNS的基础研究和临床诊疗有参考价值。     

The T1799A BRAF mutation is not a germline mutation in familial nonmedullary thyroid cancer

OBJECTIVE: Familial nonmedullary thyroid cancer (FNMTC) is relatively common but its predisposing genetic alteration is unclear. As the somatic T1799A BRAF mutation is highly prevalent in papillary thyroid cancer, the aim was to test whether this mutation was a susceptibility mutation for FNMTC. SUBJECTS AND METHODS: The T1799A BRAF mutation as a possible germline mutation was examined in 40 subjects from 23 families with a history of FNMTC. Direct DNA sequencing was performed on white blood cell DNA samples to analyse the mutation status. RESULTS: No T1799A BRAF mutation was found in this group of subjects as germline mutation. CONCLUSION: The T1799A BRAF mutation is not a germline mutation or susceptibility genetic event for FNMTC.     

A novel mutation, Ser143Pro, in the lamin A/C gene is common in finnish patients with familial dilated cardiomyopathy.

AIMS: The mutations most frequently associated with dilated cardiomyopathy (DCM) have been reported in the lamin A/C gene. The role of variants of the lamin A/C gene was investigated in patients with DCM from eastern and southern Finland. METHODS AND RESULTS: All 12 exons of the lamin A/C gene were screened in 18 well-characterised familial DCM patients from eastern and southern Finland and in 72 sporadic DCM patients from eastern Finland using the PCR-SSCP method. A novel mutation, Ser143Pro (S143P), was detected in the lamin A/C gene in 24 subjects from 5 unrelated families and in one sporadic case of DCM. Sinus or atrioventricular nodal dysfunction occurred in the majority of the affected subjects, many of which required pacemaker implantation. Seven patients (28%) with the S143P mutation died suddenly or from progressive heart failure, or underwent heart transplantation. The haplotypes 5-5-5-3, 5-5-5-2, and 5-5-5-1 co-segregated with the Ser143Pro mutation, suggesting a founder effect of this mutation. CONCLUSIONS: A novel mutation S143P in the lamin A/C gene was found to be common among Finnish DCM patients. Haplotype analysis strongly suggests a founder effect of this mutation. The phenotype is characterised by severe heart failure, progressive atrioventricular conduction defects, and sudden death. Screening for the lamin A/C gene and, particularly, the S143P mutation seems warranted when patients with DCM have conduction system disturbances.     

Analysis of the SLC26A4 gene in patients with Pendred syndrome in Taiwan

Pendred syndrome (PS) is an autosomal recessive disease that is characterized by congenital sensorineural hearing loss, goiter, and a partial iodine organification defect. In this study, we characterized the thyroid status and identified mutations in the SLC26A4 gene in Chinese subjects with PS. We evaluated 7 unrelated Chinese subjects who had PS. Biochemical analysis, formal audiogram, ultrasonography of the thyroid gland, perchlorate discharge test, computerized tomography scan of the vestibular aqueducts, and DNA sequence analysis of SLC26A4 were performed. Levels of thyroid hormones were essentially normal in all patients: 2 patients had goiters and/or elevated serum thyroglobulin levels, whereas 2 other patients had positive thyroid antibodies and a positive perchlorate discharge test. We identified SLC26A4 gene mutations in 6 of 7 probands and their affected relatives. The affected subjects in family I was compound heterozygous for 2 missense mutations: a mutation in exon 9 (1079C>T) that resulted in the replacement of alanine by valine at codon 360 (A360V) and a mutation in exon 19 (2168A>G) that resulted in the replacement of histidine by arginine at codon 723 (H723R). The affected subjects in families II and III all were homozygous for a mutation in intron 7. The probands IV and V were compound heterozygotes for the mutation in intron 7 and in exon 19, and the proband VI was compound heterozygous for the intron 7 mutation and a missense mutation in exon 12 (1343C>T) that resulted in the replacement of serine by leucine at codon 448 (S448L). One novel mutation was identified (A360V). We identified biallelic mutations in the SLC26A4 gene in 6 of 7 probands with PS in Taiwan, including a novel missense mutation. The mild thyroid dysfunction in these patients suggests that PS should be considered in all patients with congenital or early-onset hearing impairment.     

PRKAR1A gene mutation in patients with cardiac myxoma

BACKGROUND: PRKAR1A gene encodes the type 1A regulatory subunit of protein kinase A. The mutation of this gene causes Carney complex which is an autosomal dominant multiple neoplasia syndrome characterized by spotty pigmentations, endocrine overactivity and cardiac myxoma. We hypothesized that cardiac myxoma may be associated with PRKAR1A gene mutation and determined whether mutation in the PRKAR1A gene is the cause of familial and sporadic cardiac myxoma. METHODS: We studied seven patients (three males and four females) with cardiac myxoma. Two of them had familial cardiac myxoma complicated with Carney complex. The other five patients were characterized as sporadic cardiac myxomas. We analyzed the PRKAR1A gene of all patients by the polymerase chain reaction (PCR)-single-strand conformation method, followed with direct sequence analysis. RESULTS: We identified a novel mutation (494delTG) in exon 4A of the PRKAR1A gene in the patients with Carney complex. A 16-year-old proband had a left atrial myxoma, pituitary adenoma and skin pigmentation. His father also had left atrial myxoma and skin pigmentation. In contrast, no mutations in the PRKAR1A gene were identified in the other five patients with sporadic cardiac myxomas. CONCLUSIONS: These results suggest that mutation of the PRKAR1A gene may be associated with familial cardiac myxoma in Carney complex but may not be associated with sporadic cardiac myxoma.     

MYBPC3基因G12101A和MYH7基因G15391A突变与肥厚型心肌病临床表型

目的 研究中国人家族性肥厚型心肌病(HCM)的致病基因突变位点,分析基因型与临床表型的相互关系.方法 在2个中国汉族HCM家系中进行心脏肌钙蛋白T基因(TNNT2)、心脏肌球蛋白结合蛋白C基因(MYBPC3)和心脏β-肌球蛋白重链基因(MYH7)的突变筛查,聚合酶链式反应(PCR)扩增基因功能区外显子片段并对PCR产物进行测序分析.结果 在ZZJ家系接受调查的8名成员中有4名成员携带MYBPC3基因G12101A杂合突变,该突变位点位于MYBPC3基因的21号外显子并使668位的精氨酸(R)转换为组氨酸(H),携带该突变的家族成员发病年龄较晚且均无梗阻及晕厥史.在FHL家系接受调查的6名成员中有3名成员携带MYH7基因G15391A杂合突变,该突变位点位于MYH7基因的23号外显子并使930位的谷氨酸(E)转换为赖氨酸(K),该突变导致的临床表型呈现发病年龄早、梗阻率高以及外显率高的特点.两家系成员TNNT2基因未发现突变,且正常对照组相同位置未发现异常.结论 MYBPC3基凶和MYH7基因是我国家族性HCM的致病基因,MYBPC3基因G12101A突变所致HCM临床症状相对较轻,而MYH7基因G15391A突变所致HCM临床症状出现早、进展较快且预后较差,是一种恶性突变.     

A novel mutation in the SLC40A1 gene associated with reduced iron export in vitro

Ferroportin disease is an inherited disorder of iron metabolism and is caused by mutations in the ferroportin gene (SLC40A1). We present a patient with hyperferritinemia, iron overload in the liver with reticuloendothelial distribution and also in the spleen, and under treatment with erythropheresis. A molecular study of the genes involved in iron metabolism (HFE, HJV, HAMP, TFR2, SLC40A1) was undertaken. In vitro functional studies of the novel mutation found in the SLC40A1 gene was performed. The patient was heterozygous for a novel mutation, c.386T>C (p.L129P) in the SLC40A1 gene; some of his relatives were also heterozygous for this mutation. In vitro functional studies of the L129P mutation on ferroportin showed it impairs its capacity to export iron from cells but does not alter its sensitivity to hepcidin. These findings and the iron overload phenotype of the patient suggest that the novel mutation c.386T>C (p.L129P) in the SLC40A1 gene has incomplete penetrance and causes the classical form of ferroportin disease. Am. J. Hematol. 89:689–694, 2014. © 2014 Wiley Periodicals, Inc.     

Venous thromboembolism at a young age in a brother and sister with coinheritance of homozygous 20210A/A prothrombin mutation and heterozygous 1691G/A factor V Leiden mutation.

We report on members of a Turkish thrombophilic family with coinheritance of the prothrombin mutation PT20210A and the factor V Leiden mutation. The 23-year-old propositus and his elder sister both had episodes of venous theomboembolism at a young age (23 years and 26 years, respectively) and are homozygous for the PT20210A mutation and heterozygous for the factor V Leiden mutation. The 51-year-old father is suffering from coronary heart disease and is heterozygous for both thrombophilic mutations. The asymptomatic 43-year-old mother is heterozygous for the PT20210A mutation, but without activated protein C resistance. Two other children, a 20-year-old girl who is homozygous for the PT20210A mutation and a 13-year-old boy who is heterozygous for the PT20210A mutation, are both free from activated protein C resistance and thrombosis. This report provides further evidence for an early onset of thromboembolic disorders in individuals with an homozygous state of the prothrombin variant 20210A/A and coinheritance of another thrombophilic mutation. Consensus guidelines are required for the treatment and prophylaxis of patients and subjects who remain asymptomatic with homozygous or more than one heterozygous genetic defect associated with thrombophilia.     

Detection of hepatitis B virus A1762T/G1764A mutant by amplification refractory mutation system

ObjectiveTo study the role of hepatitis B virus with A1762T/G1764A double mutation in liver cirrhosis and hepatocellular carcinoma, and create a sensitive, fast, accurate assay for detection of A1762T/G1764A double mutation.MethodsWe developed an accurate and fast real-time amplification refractory mutation system to detect A1762T/G1764A double mutation. Cloned hepatitis B virus genome was used as a control. Assay sensitivity was determined by serial dilution and mixed template experiments. Specificity was determined by cross experiments with wild and mutant hepatitis B virus. Fifty clinical samples were tested by the real-time amplification refractory mutation system and the results were compared with sequencing.ResultsThe real-time amplification refractory mutation system had a sensitivity of 100 copies of virus with these mutations, and 0.1% weak population virus with double mutation could be found in mixtures. A total of 50 randomly collected clinical samples were detected by real-time amplification refractory mutation system, and the results were consistent with those by DNA sequencing. Hepatitis B virus genotype C was more prevalent in 39 of 50 samples than genotype B (11 samples), and about 75% of genotype C carried a double mutation compared to 45% of genotype B. However, the percentage of A1762T/G1764A double mutation in hepatitis B e antigen-negative (58.3%) samples was almost the same as in hepatitis B e antigen-positive (61%) samples.ConclusionThe real-time amplification refractory mutation system is sensitive and specific for detection of hepatitis B virus double mutation.     

Prothrombin G20210A gene mutation with LightCycler polymerase chain reaction in venous thrombosis and healthy population in the southeast of Turkey

Venous thrombosis (VT) is a common disease, with an annual incidence in the general population of approximately 1 per 1000. The prevalence of genetic risk factors for thrombosis varies greatly in different parts of the world. Prothrombin G20210A (PT G20210A) gene mutation has been recently identified as a common risk factor in venous thrombosis. Sixty-one patients with VT, differing in age and sex, and 340 healthy subjects were consecutively enrolled into our study to determine the prevalence of PT G20210A in VT and in the healthy population of the southeast of Turkey. The mutation was identified with fluorescence resonance energy transfer (FRET) with the LightCycler polymerase chain reaction. The PT G20210A mutation was found to be 6.5% (4/61) in the VT group and 1.2% (4/340) in the healthy group (P = 0.021). Three patients with VT had a heterozygous PT G20210A mutation, and the other patient with VT had both Factor V Leiden and PT G20210A mutations. We showed that this method may be used safely for detection of the PT G20210A gene mutation, and the prevalence of PT G20210A mutation is significantly higher in patients with VT than in the healthy population in the southeast of Turkey.     

家族性高胆固醇血症基因突变及临床表型研究

目的 筛查家族性高胆同醇血症家系载脂蛋白(Apo)B100基因及低密度脂蛋白受体(LDLR)基因突变,并探讨其临床表现.方法 采用PCR扩增ApoB100基因包含3500、3501、3531和3480位点的序列;扩增LDLR启动子和全部18个外显子片段,产物电泳鉴定后直接序列分析,结果 与GenBank公布的基因正常序列比对,找出突变.结果 该家系LDLR基因第10外显子的第1581位碱基发生G＞A突变,导致G496E突变;未检出ApoB100基因突变.结论 此突变为一新突变,为该家系致病性突变.

Abstract：

Objective To investigate the low density lipoprotein receptor (LDLR)gene and apolipoprotein (Apo) B gene mutation in a Chinese family with familial hypercholesterolemia(FH) and give the kindrids clinical check-ups. Methods After physical examination, the kindreds underwent ECG and ultrasound checks. Blood samples were tested for lipid profiles. The promoter and all eighteen exons of LDLR gene were investigated by using PCR and agarose gel electrophoresis in combination with DNA sequence analysis. The results were compared with the normal sequences in GenBank and FH database ( www. ucl. ac. uk/fh ) to find mutations. In addition, the apolipoprotein B100 gene for known mutations (R3500Q,R3531C,R3501W and R3480W)that cause familial defective ApoB100 (FDB)was also tested using the same method. Results A novel homozygous G ＞ A mutation at the 1581 bp of exon 10 was detected in the proband and his siblings. It caused a substitution of amimo acid Glu to Gly at codon 496. A novel heterozygous G ＞A mutation at the 1581 bp of exon 10 was detected in his parents. No mutations of R3500Q,R3531C,R3501W and R3480W of ApoB100 were observed. ECGs were normal. Atherosclerosis were found in all family members by ultrasound checks. Conclusions The homozygous G ＞ A mutation at the 1581 bp of exon 10 was first determined in our country. The change of amino acid Glu to Gly is responsible for FH of the family. The type of the gene mutation was not found in the FH database( www. ucl.ac. uk/ih). It's a new type of LDLR mutation.     

Prevalence of the G20210A prothrombin gene mutation in Northwestern Greece and association with venous thromboembolism.

AIM: The G20210A mutation of the prothrombin gene is a genetic risk factor for venous thromboembolism (VTE). Variability exists in the mutation prevalence in both normal individuals and VTE patients. The aim of this study was to determine the mutation prevalence in Northwestern Greece and evaluate its association with VTE. METHODS: Presence of the G20210A mutation was investigated using DNA analysis in 176 consecutive patients with a history of venous thrombosis or pulmonary embolism and in 300 healthy controls, all Caucasian residents of Northwestern Greece. RESULTS: The mutation was present 12 patients (6.8%) and 8 controls (2.7%). The odds ratio for presence of the mutation versus the normal genotype in VTE was 2.7 (95% CI: 1.1 to 6.7), which was statistically significant. The prevalence of the G20210A prothrombin gene mutation in Northwestern Greece is 2.7% (95% CI: 0.8% to 4.4%) with an allele frequency of 1.3% (95% CI: 0.4% to 2.3%). CONCLUSION: The G20210A mutation of the prothrombin gene is associated with VTE in the Caucasian residents of this geographic region.