Clinical symptoms, diagnosis and treatment of multiple endocrine neoplasia type 1. Results of genetic screening in Hungarian patients

Multiple endocrine neoplasia type 1 syndrome is an autosomal dominant disorder characterized by endocrinopathies involving the parathyroid glands, anterior pituitary gland, and pancreas. Also, it may be associated with foregut carcinoid, adrenocortical tumors and non-endocrine tumors. After reviewing the prevalence, genetic background, clinical symptoms, diagnosis and treatment of the disorder, the authors present their genetic screening method used for the detection of mutations of the MEN1 gene (prescreening of polymerase chain reaction amplified exons using temporal temperature gradient gel electrophoresis followed by direct DNA sequencing). Using this method, the authors identified disease-causing MEN1 gene mutations in 9 probands (small deletions in 2 cases, insertion in 2 cases, nonsense mutations in 2 cases and missense mutations in 3 cases). Of the 9 mutations, 4 proved to be novel mutation not reported in the literature. Family screening indicated de novo mutations in 2 probands. In addition to mutations, several sequence polymorphisms were also detected. The authors conclude that one of the major advantages of genetic screening in families with MEN1 syndrome was the identification of family members carrying the mutation who should be regularly screened for disease manifestations and those not carrying the mutation in whom clinical screening is unnecessary. Also, genetic screening may be useful in cases when MEN1 syndrome is suspected, but the clinical manifestations do not fully establish the diagnosis of MEN1 syndrome.     

Associations of clinical features in neurofibromatosis 1 (NF1)

Neurofibromatosis 1 (NF1), an autosomal dominant disease, exhibits extreme clinical variability. This variability greatly increases the burden for affected families and impairs our ability to understand the pathogenesis of NF1. Recognition of heterogeneity within a disease may provide important pathogenic insights, therefore we tested clinical data from three large sets of NF1 patients for evidence that certain common features are more likely to occur in some NF1 patients than in others. Clinical information on 4,402 patients with NF1 was obtained from three independent databases. We examined associations between pairs of clinical features in individual affected probands. We also examined associations between the occurrence of individual features in affected relatives. Associations were summarized as odds ratios with 95% confidence intervals. We found associations between several pairs of features in affected probands: intertriginous freckling and Lisch nodules, discrete neurofibromas and plexiform neurofibromas, discrete neurofibromas and Lisch nodules, plexiform neurofibromas and scoliosis, learning disability or mental retardation and seizures. We also found associations between the occurrence of Lisch nodules, macrocephaly, short stature, and learning disability or mental retardation as individual features in parents and children with NF1. Our observations suggest that, contrary to established belief, some NF1 patients are more likely than others to develop particular manifestations of the disease. Genetic factors appear to determine the development of particular phenotypic features.     

永久性甲状腺功能减低症患儿相关基因突变的研究

目的探讨永久性甲状腺功能减低症患儿的基因突变位点与临床表型的关系。方法回顾2013年至2015年在自贡市新生儿疾病筛查中心诊治并随访的2例及既往诊断的8例永久性甲状腺功能减低症患儿的临床资料,并对其中5例患儿的甲状腺过氧化酶(TPO)、双氧化酶2(Duox2)、双氧化酶辅助因子2(DuoxA2)及甲状腺转录因子Pax8基因采用Sanger方法进行测序,了解其基因突变位点的类型及与临床表型的关系。结果在5例永久性甲状腺功能减低症患儿中,2例为DuoxA2基因突变,1例为Duox2基因突变,以上两种基因突变类型的甲状腺形态均正常;另外2例未检出基因突变,但临床表型为甲状腺缺如。结论DuoxA2、Duox2可能为自贡地区永久性甲状腺功能减低症患儿的主要基因突变类型,但临床表现甲状腺缺如症状患儿的基因突变类型未检出,需今后进一步明确。     

From gene to disease; neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant disease characterised by café-au-lait spots, freckling in the axillary or inguinal region, dermal and plexiform neurofibromas and Lisch nodules. Complications are severe in one third of patients, and the clinical variability is pronounced, even within families. The NF1 gene has been localised to chromosome 17q11.2 and encodes the protein neurofibromin. The gene is proposed to be a tumour suppressor gene. Inactivation of neurofibromin leads to a disruption in cell growth regulation. Mutation analysis is possible but laborious, and therefore NF1 is generally a clinical diagnosis based on diagnostic criteria.     

Mismatch repair genes hMLH1 and hMSH2 and colorectal cancer: a HuGE review

Evidence to support a role for the mismatch repair genes human mutL homolog 1 (hMLH1) and human mutS homolog 2 (hMSH2) in the etiology of colorectal cancer has come from linkage analysis, segregation studies, and molecular biologic analysis. More recently, carriers of potentially pathogenic mutations in the hMLH1/hMSH2 genes have consistently been shown to be at a greatly increased risk of developing colorectal cancer compared with the general population. When considered together, the available evidence shows a strong, consistent, and biologically plausible association between mismatch repair gene mutations and colorectal cancer. The penetrance of mutations in hMLH1/hMSH2 is incomplete and is significantly higher in males (approximately 80%) than in females (approximately 40%). To date, evidence for gene-gene or gene-environment interactions is limited, although preliminary studies have revealed a number of avenues that merit exploration. Population screening for mutation carriers is not currently a feasible option, and mutation analysis remains restricted to either relatives of mutation carriers or colorectal cancer cases selected on the basis of phenotype.     

GCH1基因剪切突变致多巴反应性肌张力障碍1例

目的探讨多巴反应性肌张力障碍GCH1基因突变方式及遗传特点,从而加深对本病的认识。方法回顾性分析1例多巴反应性肌张力障碍(DRD)患儿临床表现及其家系基因检测资料。结果患儿与其父亲均存在GCH1基因c.542-2A>T的核苷酸杂合突变,属于剪切变异,该病例诊断为DRD,予以美多芭治疗后患儿临床表现显著好转。结论该例患儿及其父亲均为GCH1基因内含子相同部位的剪切突变,对于儿童DRD的诊断,基因检测是重要的检测手段,GCH1基因常见突变主要发生在外显子,但仍需注意内含子部位突变的致病性。     

具有SCN1A基因错义突变(R1596C)的遗传性GEFS+家系1例报道

目的总结一个全面性癫痫伴热性惊厥附加症(generalized epilepsy with febrile seizures plus,GEFS+)家系的钠通道α1基因(voltage-gated sodium channelα1-subunit,SCN1A)及其临床特性。方法总结该家系患者的临床特征,应用变性高效液相色谱(denaturing high performance liquid chromatography,DHPLC)技术筛查SCN1A全部26个外显子,对发现有异常洗脱峰者再进行直接测序。结果该家系中三位患者均具有典型GEFS+的临床特点,她们在SCN1A基因第25号外显子发现有相同的杂合突变(c.4876C>T),并导致编码的氨基酸改变(R1596C)。结论GEFS+是呈常染色体显性方式遗传的一种癫痫综合征,可由SCN1A基因错义突变导致。     

肺癌组织miR-125b-1基因突变的初步分析

[目的]检测miR-125b-1基因在人肺癌组织中的突变情况,以探讨该基因在肺癌发生发展中的作用.[方法]采用聚合酶链反应-单链构象多态性分析(polymerase chain reaction and single-strand conformation polymorphism, PCR-SSCP)检测肺癌原发灶癌组织miR-125b-1基因突变情况.[结果]miR-125b-1在癌旁正常肺组织中未发现异常,在肺癌组织中存在基因突变,突变率33.1%(40/121例),miR-125b-1基因突变与与癌的淋巴结转移及临床分期呈显著相关,Spearman相关分析显示两者呈显著正相关.与其他临床病理特征无关.[结论]肺癌组织中存在着miR-125b-1基因突变,miR-125b-1基因突变在肺癌的发生发展中可能起着重要作用.     

Androgen insensitivity syndrome: clinical features and molecular defects

The end-organ resistance to androgens has been designated as androgen insensitivity syndrome (AIS), an X-linked disorder caused by mutations in the androgen receptor (AR) gene. It is generally accepted that defects in the AR gene prevent the normal development of both internal and external genital structures in 46,XY individuals, causing a variety of phenotypes ranging from male infertility to completely normal female external genitalia. Precise diagnosis requires clinical, hormonal and molecular investigation and is of great importance for appropriate gender assignment and management in general. The complexity of phenotypic presentation of AIS with genotype-phenotype variability of identical mutations complicates both the diagnostic procedure and genetic counseling of the affected families. More than 400 different AR gene mutations have thus far been reported but the receptor structure-function relationship and its phenotypic outcome is not yet fully understood. This review focuses on the clinical features and molecular pathophysiology of AIS and explores the relationship of the molecular defects in the AR gene to their clinical expression.     

乳腺癌中BRCA1基因突变与雌激素受体的关系

目的探讨遗传性乳腺癌与卵巢癌易感基因(Hereditarybreastandovariancancersusceptibilitygene,BRCA1)基因突变、雌激素受体(Estrogenreceptor,ER)在乳腺癌中的作用以及二者之间的关系。方法选取64例乳腺癌患者标本作研究组,另取10例非癌乳腺组织标本作对照组。利用PCR-SSCP法和直接测序法检测BRCA1基因突变情况;利用SP(链霉菌抗生物素蛋白-过氧化物酶链接法)二步法检测ER,比较ER阳性组与ER阴性组BRCA1突变情况。结果10例非乳腺癌组织未检测出BRCA1基因突变。64例乳腺癌标本中检出BRCA1基因突变6例,突变率为9.4%。突变发生在5、12、17外显子上,均为错义突变,ER阳性44例,阳性率为68.75%(44/64)。ER阳性组中只有1例BRCA1突变(1/44),ER阴性组中有5例检出BRCA1突变(5/20),两组比较BRCA1突变率有显著差异性(P>0.05)。结论广西乳腺癌与BRCA1基因突变有关,BRCA1突变与雌激素受体有关,BRCA1基因突变病人雌激素阴性状态比非BRCA1基因突变病人多。     

Public health aspects of genetic screening for hereditary haemochromatosis in Australia

Hereditary haemochromatosis (HH) is an inherited disorder of iron absorption. It meets several of the key public health principles for population-based screening and is considered to be a test-case for public health genetics. However, there has been relatively little debate in the public health or wider community regarding the merits of population-based genetic screening for HH. Genetic susceptibility to HH occurs in about 1:200 people and although mortality is low (age-standardised rate 2.75/million), there are potentially serious clinical manifestations of iron overload. Regular venesection is a simple and effective treatment for early stage iron overload. DNA-based testing is available and iron overload may be identified using serum transferrin saturation and ferritin tests. However, there are important gaps in knowledge relevant to screening for HH. The limited data on penetrance of HFE genotypes, and thus the uncertain probability that genetically susceptible individuals will develop clinically significant disease, is a major impediment to population-based genetic screening. Clinical evidence supports treating early-stage disease but no randomised controlled trials of the effectiveness of screening in reducing the burden of disease have been conducted. In addition, the natural history of early stages of HH and factors that may modify progression are unclear. Two intemational consensus panels on HH concluded that there is insufficient evidence for population-based screening at present. We present recommendations to advance the debate on screening for HH in Australia.     

Intrafamilial correlation of clinical manifestations in neurofibromatosis 2 (NF2)

Measuring correlation in clinical traits among relatives is important to our understanding of the causes of variable expressivity in Mendelian diseases. Random effects models are widely used to estimate intrafamilial correlations, but such models have limitations. We incorporated survival techniques into a random effects model so that it can be used to estimate intrafamilial correlations in continuous variables with right censoring, such as age at onset. We also describe a negative-binomial gamma mixture model to determine intrafamilial correlations of discrete (e.g., count) data. We demonstrate the utility of these methods by analyzing intrafamilial correlations among patients with neurofibromatosis 2 (NF2), an autosomal-dominant disease caused by mutations of the NF2 tumor-suppressor gene. We estimated intrafamilial correlations in age at first symptom of NF2, age at onset of hearing loss, and number of intracranial meningiomas in 390 NF2 nonprobands from 153 unrelated families. A significant intrafamilial correlation was observed for each of the three features: age at onset (0.35; 95% confidence interval (CI) 0.23-0.47), age at onset of hearing loss (0.51; 95% CI, 0.35-0.64), and number of meninginomas (0.29; 95% CI, 0.15-0.43). Significant correlations were also observed for age at first symptom within NF2 families with truncating mutations (0.41; 95% CI, 0.06-0.68) or splice-site mutations (0.29; 95% CI, 0.03-0.51), for age at onset of hearing loss within families with missense mutations (0.67; 95% CI, 0.18-0.89), and for number of meningiomas within families with splice-site mutations (0.39; 95% CI, 0.13-0.66). Our findings are consistent with effects of both allelic and nonallelic familial factors on the clinical variability of NF2.     

Some public health issues in the current state of genetic testing for breast cancer in Australia

Abstract: Two genes associated with a high breast cancer risk ( BRCA1 and BRCA2 ) have been discovered recently from study of large breast-cancer-dense kindreds. It is problematic to make inferences from these atypical families to the general population. Nevertheless, it appears that about 1 to 2 per cent of all breast cancer may be due to rare deleterious mutations in BRCA1 or BRCA2 . The majority of breast cancer families with fewer than four cases are likely to have cancers not attributable to these genes. There may be more common mutations in other genes (such as ATM, HRAS1 ) that confer a moderate risk of breast cancer, and may account for 5 to 15 per cent of cases. At this early stage of cancer genetics, the risks associated with particular mutations are not known, there are no proven and acceptable strategies for women with an inherited susceptibility to ameliorate risk or improve prognosis, and risk estimates appropriate for Australian women with a family history of breast cancer are not established, although data from the United States may overestimate risk. Information is needed from population-based studies, such as the Australian Breast Cancer Family Study (Hopper et al. Breast 1994; 3: 79–86), but 100 per cent mutation detection in large cancer genes is difficult and expensive. Development of a systematic, research-oriented, evidence-based approach to genetic testing in Australia is recommended. Australia could lead the world in having common protocols used in breast cancer clinics across the country, linked to a national research consortium and database.     

Unusual clinical manifestations of type 1 neurofibromatosis

Type 1 neurofibromatosis is an autosomal dominant hamartosis caused by mutations of the neurofibromin-1 gene. The classic features of the clinical phenotype include the presence of café-au-lait spots, neurofibromas, axillary and inguinal freckling, Lisch-nodules and deformities of the skeletal system, as well as the risk of developing multiple tumors, especially in the central nervous system. However, it is known from the literature that the phenotypic variability can pose a huge diagnostic difficulty. Aims: Our institute performs molecular genetic testing of the neurofibromin-1 gene since 2008; during this period several unusual phenotypic variants were found. Results, conclusion: The reported four cases represent interesting phenotypic variants or diagnostic challenges in which the final diagnosis was established by molecular genetic analysis.     

Familial Mediterranean Fever (FMF): from diagnosis to treatment

Familial Mediterranean Fever (FMF), also known as paroxysmal polyserositis, is an autosomal recessive disease affecting mainly Mediterranean populations (Jews, Armenians, Arabs, Turks). It is characterised by recurrent crises of fever and serosal inflammation, leading to abdominal, thoracic or articular pain. Erysipela-like erythema affecting mainly feet and legs and effort-induced myalgia are less frequently encountered symptoms. The major complication of FMF is the development of renal amyloidosis. Standard laboratory tests of FMF patients are non-informative, except for the high sedimentation rate and white blood cell count, but during and immediately after crises, diminished albumin concentrations and elevated fibrinogen, C-reactive protein, beta2 and alpha2 M globulins, haptoglobin and lipoprotein concentrations are noted. Studies have measured immunoglobulin (Ig) levels in the sera of FMF patients and found elevated levels of IgA, IgM, IgG, and IgD in 23%, 13%, 17% and 13%, respectively. FMF crises are characterised by a massive influx of polymorphonuclear leukocytes into the inflamed regions. Moreover, the peritoneal fluid of FMF patients contains abnormally low levels of the inhibitor of complement fragment C5a and interleukin 8. Failure to suppress inflammatory response to C5a may explain the typical inflammatory FMF crises. The MEFV (for MEditerranean FeVer) gene responsible for the disease has been identified on 16p13.3. It is composed of 10 exons and spans approximately 14 Kb of genomic DNA. More than 35 mutations have so far been identified. The most frequent are M694V, M694I, M680I, V726A and E148Q. The M694V mutation is the most frequent mutation in the various ethnic groups considered, although its frequency varies from group to group. The V726A mutation is observed mainly among Ashkenazi and Iraqi Jews, Druzes and Armenians, and the M680I among Armenians and Turks. M694I and A744S seem specific to Arab populations, and R761H is frequently found in Lebanese FMF patients. The M694V mutation is often correlated with severe phenotypes, mainly in the homozygous state. It has been specifically correlated with arthritis, pleuritis and especially amyloidosis. Patients with other mutations in the 694 and 680 codons can also have severe phenotypes. The V726A mutation, although identified in FMF patients with a relatively mild phenotype, has also been detected in patients with renal amyloidosis. E148Q is often associated with a mild phenotype, and whether it is even a polymorphism has been questioned. The MEFV gene codes for a protein that was respectively called pyrin and marenostrin by the French and international consortia that simultaneously identified the gene. Its function is still not determined, but it was recently colocalised with microtubules and actin filaments in the cytoplasm. It contains a death domain called PYD (Pyrin Domain), usually associated with proteins involved in apoptosis. Some genes have been tested to assess their possible modifying effects on clinical features of FMF. The alpha/alpha genotype of the serum amyloid A or SAA1 gene is associated with an increased risk of amyloidosis in FMF patients, especially in patients homozygous for M694V, whereas the MICA (Major Histocompatibility Complex, MHC class-I-chain-related type A) gene seems to have an effect on disease course but not its clinical manifestations. The most effective treatment for FMF patients is colchicine, which should be taken regularly on a life-long basis. It decreases the frequency and severity of crises and prevents renal amyloidosis.     

BRCA1 and BRCA2 gene mutations and risk of breast cancer. Public health perspectives.

CONTENT: Breast cancer is the most common cancer and the second most common cause of cancer death among U.S. women. In 1998, about 178,700 new cases will be diagnosed and 43,500 women will die from the disease. Mutations in the BRCA1 gene, which was cloned in 1994 and is located on chromosome 17q, have been identified as causes of predisposition to breast, ovarian, and other cancers. A second breast cancer gene, BRCA2, has been localized to chromosome 13q. Using inferential procedures, the overall carrier frequency of BRCA1 gene mutations has been estimated at 1 in 500 in the general U.S. population. Recent studies have indicated that the carrier frequency of a specific BRCA1 allele, the 185delAG mutation, may be as high as 0.8% to 1% among women of Ashkenazi Jewish descent. CONCLUSIONS: Due to the proliferation of laboratories offering genetic tests for breast cancer susceptibility, their appropriate use in public health needs careful scrutiny. Several issues are raised when such genetic tests are considered for population-based prevention programs for breast cancer. Public health agencies, such as the Centers for Disease Control and Prevention, are important to monitoring and evaluating genetic testing done outside of research protocols. If genetic tests for breast cancer are to be incorporated into future prevention programs, evaluation is needed of whether the testing can have the intended effect.     

谷胱甘肽合成酶缺乏症2例基因分析及文献回顾

目的 探讨谷胱甘肽合成酶缺乏症(GSSD)的临床及遗传学特点.方法 对2014年1至12月西安市儿童医院内分泌遗传代谢科临床诊断的2例5-羟脯氨酸尿症的患儿进行临床特点分析,采用目标序列捕获测序方法,对患儿进行谷胱甘肽合成酶(GSS)基因分析,再经聚合酶链式反应(PCR)对高危突变基因进行验证,最终确诊为GSSD;并进行相关临床特点总结及基因学分析.结果 GSSD临床表现为代谢性酸中毒、黄疸、溶血性贫血,GSS基因检测出致病突变,其中1例为复合杂合突变(E5 c.491G>A和E10 c.847C>T),1例为纯合突变(E5 c.491G>A).结论 E5 c.491G>A基因突变可能为GSSD热点基因突变.     

新生儿中链酰基辅酶A脱氢酶缺乏症筛查和基因突变分析

目的 了解青岛地区新生儿中链酰基辅酶A脱氢酶缺乏症(MCADD)的患病率、临床特征及基因突变特点。方法 2015年1月-2018年8月利用串联质谱技术检测278 180例在青岛地区出生的新生儿干血滤纸片中酰基肉碱水平,对筛查出的疑似MCADD患儿通过尿有机酸检测,中链酰基辅酶A脱氢酶编码基因(ACADM)基因突变检测进行确诊。结果 共确诊4例中链酰基辅酶A脱氢酶缺乏症患儿,患病率0.001 4%(1/69 545)。患儿临床表现无明显异常,串联质谱检测均有中链酰基肉碱(C6~C10)升高。4例患儿共检测到7种ACADM基因突变,其中1例患儿为纯合突变,为c.1 040G>T(p.G347V)/ c.1 040G>T(p.G347V),其它3例为复合杂合突变,分别为:c.157C>T(p.R53C)/ c.709-1G>A;c.1 085G>A(p.G362E)/ c.461T>G(p.L154W);c.587G>A(p.G196E)/ c.387+1delG。尿有机酸检测1例患儿4-羟基-苯乙酸和4-羟基苯丙酮酸指标升高,肝功能异常。对患儿进行饮食指导,随访均未出现临床症状,体格及智力发育正常。结论 串联质谱新生儿筛查配合基因检测可以对MCADD早诊断,对预防疾病发作和提高患儿生活质量有重要意义。