应用分子生物学技术产前诊断Down综合征

目的 探讨应用PCR分子生物学方法产前诊断Down综合征（Down syndrome,DS)。方法 取产前诊断病例：羊水100例，绒毛16例。提取DNA，PCR扩增21号染色体的6个多态位点，电泳，膜转移，等位基因位点分析，诊断。结果 正常人为两种带型：杂合型显示两条带，纯合型一条带。Down综合征患者为三种带型：完全杂合型显示三条带，半杂合型两条带（信号增强的2：1带），纯合型一条带。100例羊水中2例阳性，16例绒毛标本中1例阳性，3例患者，至少有2个位点检出三个等 基因，患者为2个位点时，表现2：1带型；无一例正常检出三个等位基因。所有结果均与细胞染色体核型检查相符。结论 本分子生物学方法产前诊断DS简便、快速、可行，是一种值得推广的方法。     

Marfan syndrome: clinical diagnosis and management

Marfan syndrome is a multisystem connective tissue disorder usually associated with mutation in fibrillin, and occasionally with mutation in TGFBR1 or 2. The clinical diagnosis is made using the Ghent nosology, which will unequivocally diagnose or exclude Marfan syndrome in 86% of cases. Use of a care pathway can help implementation of the nosology in the clinic. The penetrance of some features is age dependent, so the nosology must be used with caution in children. Molecular testing may be helpful in this context. The nosology cannot be used in families with isolated aortic dissection, or with related conditions such as Loeys-Dietz syndrome, although it may help identify families for further diagnostic evaluation because they do not fulfill the nosology, despite a history of aneurysm. Prophylactic medical (eg beta-blockade) and surgical intervention is important in reducing the cardiovascular complications of Marfan syndrome. Musculoskeletal symptoms are common, although the pathophysiology is less clear--for example, the correlation between dural ectasia and back pain is uncertain. Symptoms in other systems require specialist review such as ophthalmology assessment of refractive errors and ectopia lentis. Pregnancy is a time of increased cardiovascular risk for women with Marfan syndrome, particularly if the aortic root exceeds 4 cm at the start of pregnancy. High-intensity static exercise should be discouraged although low-moderate intensity dynamic exercise may be beneficial. The diagnosis and management of Marfan syndrome requires a multidisciplinary team approach, in view of its multisystem effects and phenotypic variability.     

马方综合征的诊断与治疗研究进展

马方综合征(MFS)是一种常染色体显性遗传结缔组织疾病,发病率为2/10000~3/10000。MFS易累及心血管系统、骨骼系统、视觉系统等,其心源性猝死发生率明显高于正常人群。临床主要依据2010年修订版Ghent诊断标准进行诊断,基因检测可以协助诊断。MFS的治疗有内科治疗与手术治疗,内科治疗主要延缓病情发展,改善瓣膜反流;外科手术治疗选择置换主动脉根部及主动脉瓣的Bentall。早期有效诊断、及时干预治疗可以延缓MFS的病理进展。     

应用PCR-STR分型技术快速产前基因诊断Down综合征

目的探讨应用PCR-STR分型技术,快速产前基因诊断Down综合征(Down syndrome,DS)方法.方法选择21号染色体上的4个短串联重复序列D21S2055、D21S1244、D21S1435和D21S1809,进行PCR扩增,尿素非变性聚丙烯酰胺凝胶电泳,银染分型.根据谱带的条数及浓度判断是否为21三体,根据父母基因型判断额外21号染色体的亲代来源,选择30例高危孕妇进行21三体的产前基因诊断.结果应用此方法可检出所有的由核型分析确诊的单纯型21三体,并可判定额外染色体的亲代来源.30例产前诊断筛出2例21三体患儿.结论该方法不用细胞培养,避免放射性标记,并可进行早期产前诊断.该方法比传统的方法操作简单、速度快,是一种产前诊断和大规模筛查21三体的良好的方法.     

Marfan综合征的基因突变及基因诊断

Marfan综合征是常染色体显性遗传性结缔组织疾病,发病率为0.2‰～0.3‰,病变主要涉及骨骼、眼睛、心血管系统,有时也涉及肺部、皮肤和硬脑脊膜等器官.目前研究认为Marfan综合征发病主要原因为原纤维蛋白基因(fibrillin-1,FBN1)的突变.本文主要介绍了与Marfan综合征相关的FBN1基因及突变特点,重点对目前基因诊断研究情况加以概述.     

The molecular genetics of Marfan syndrome and related microfibrillopathies

Mutations in the gene for fibrillin-1 (FBN1) have been shown to cause Marfan syndrome, an autosomal dominant disorder of connective tissue characterised by pleiotropic manifestations involving primarily the ocular, skeletal, and cardiovascular systems. Fibrillin-1 is a major component of the 10-12 nm microfibrils, which are thought to play a role in tropoelastin deposition and elastic fibre formation in addition to possessing an anchoring function in some tissues.
  Fibrillin-1 mutations have also been found in patients who do not fulfil clinical criteria for the diagnosis of Marfan syndrome, but have related disorders of connective tissue, such as isolated ectopia lentis, familial aortic aneurysm, and Marfan-like skeletal abnormalities, so that Marfan syndrome may be regarded as one of a range of type 1 fibrillinopathies.
  There appear to be no particular hot spots since mutations are found throughout the entire fibrillin-1 gene. However, a clustering of mutations associated with the most severe form of Marfan syndrome, neonatal Marfan syndrome, has been noted in a region encompassing exons 24 to 32. The gene for fibrillin-2 (FBN2) is highly homologous to FBN1, and mutations in FBN2 have been shown to cause a phenotypically related disorder termed congenital contractural arachnodactyly. Since mutations in the fibrillin genes are likely to affect the global function of the microfibrils, the term microfibrillopathy may be the most appropriate to designate the spectrum of disease associated with dysfunction of these molecules.
  The understanding of the global and the molecular functions of the fibrillin containing microfibrils is still incomplete and, correspondingly, no comprehensive theory of the pathogenesis of Marfan syndrome has emerged to date. Many, but not all, fibrillin-1 gene mutations are expected to exert a dominant negative effect, whereby mutant fibrillin monomers impair the global function of the microfibrils. In this paper we review the molecular physiology and pathophysiology of Marfan syndrome and related microfibrillopathies.


Keywords: Marfan syndrome; fibrillin; microfibrillopathies     

The molecular genetics of Marfan syndrome and related disorders

Marfan syndrome (MFS), a relatively common autosomal dominant hereditary disorder of connective tissue with prominent manifestations in the skeletal, ocular, and cardiovascular systems, is caused by mutations in the gene for fibrillin-1 (FBN1). The leading cause of premature death in untreated individuals with MFS is acute aortic dissection, which often follows a period of progressive dilatation of the ascending aorta. Recent research on the molecular physiology of fibrillin and the pathophysiology of MFS and related disorders has changed our understanding of this disorder by demonstrating changes in growth factor signalling and in matrix-cell interactions. The purpose of this review is to provide a comprehensive overview of recent advances in the molecular biology of fibrillin and fibrillin-rich microfibrils. Mutations in FBN1 and other genes found in MFS and related disorders will be discussed, and novel concepts concerning the complex and multiple mechanisms of the pathogenesis of MFS will be explained.     

Cri-du-chat syndrome: clinical profile and prenatal diagnosis

Prenatal diagnosis of cri-du-chat syndrome is described in 2 pregnancies. In Case 1, the mother was a balanced translocation carrier and had 2 previously affected off springs. Prenatal diagnosis by chorion villus sampling and cordocentesis was successful in diagnosing an affected conceptus and the pregnancy was electively terminated. Case 2 was referred for nonimmune foetal hydrops and cordocentesis revealed deletion 5p. This second case was noteworthy for the fact that deletion 5p has not been reported to cause foetal hydrops.     

Angelman综合征的诊断及其产前诊断

目的 对临床疑似Angelman综合征(Angelman syndrom,AS)的患者进行诊断并对已确诊的患儿家庭行产前诊断.方法 用高分辨染色体和荧光原位杂交(fluorescence in situ hybridization,FISH)技术对患者进行检测.结果 诊断出两例AS患者和一名正常胎儿.结论 结合临床症状、高分辨核型分析、FISH可确诊Ⅰ型AS患者,为临床提供准确的遗传咨询和产前咨询,并可对有AS生育史的家庭行产前诊断.     

Diagnostic, predictive, and prenatal testing for facioscapulohumeral muscular dystrophy: diagnostic approach for sporadic and familial cases.

Facioscapulohumeral muscular dystrophy (FSHD) is one of the common inherited neuromuscular disorders. The major gene involved, FSHD1, has been localised to chromosome 4q35. This 4q35 locus, detected by pE13-11 (D4F104S1), shows a mutation frequency of about 10% of the incidence. New mutants are characterised by de novo deletions of tens to hundreds of kilobases of DNA. Although these deletion fragments are very useful as a molecular genetic tool, their use in diagnostic DNA testing is hampered by multiple factors, particularly in familial cases. In this report we describe a protocol that can be used for DNA testing in well defined familial cases or proven de novo cases, and in the differential diagnosis of muscular dystrophy patients clinically suspected of having FSHD. In addition, we describe a prenatal diagnosis performed for FSHD1.     

Multiple pollen sensitization: a molecular approach to the diagnosis

BACKGROUND: Sensitization to multiple pollen species is a frequent diagnostic event. Several allergenic molecules with a high level of homology have been identified in divergent pollen families and named panallergens. METHODS: We sought to define the criteria to evaluate the prevalence of the multiple pollen sensitization, to identify specific markers of this condition, and to correlate them with the underlying allergic disease. Patients presenting an allergic respiratory disease underwent skin testing with 23 pollens. Patients fulfilling predefined selection criteria were grouped and classified as having multiple pollen sensitization. Patients in each subgroup were tested for IgE to rBet v 2, rJun o 2, rBet v 1, rPhl p 5 and bromelain. Demographical, allergological and clinical data were recorded in the subgroup of patients with multiple pollen sensitization. RESULTS: Seventeen percent of the pollen-sensitized patients formed the multiple pollen-sensitized subgroup. These subjects were positive for most of the pollen species tested regardless of known exposure to them. None of the subjects sensitized to less than six pollen species were positive to panallergens, whereas 55% of the sera of the multiple pollen-sensitized group were positive to rBet v 2, and 15% to rJun o 2. IgE to rBet v 1 and rPhl p 5 were found positive in all the subgroups. Age, gender, bronchial asthma, oral allergy syndrome, skin test reactivity and previous specific immunotherapy differed significantly when these two subsets were considered. CONCLUSIONS: Allergy diagnosis based on allergenic molecules is crucial in the patient with multiple pollen sensitization. This condition appears to be determined by the sensitization to defined allergenic components (panallergens) rather than by pollen of multiple species as such. Detection of IgE to nonpanallergenic molecules allows to identify more relevant allergenic sources. Clinical aspects of the underlying allergic disease (e.g. asthma and oral allergy syndrome) seem to be differently related to IgE reactivity to panallergens.     

Lymphedema in Noonan syndrome: clues to pathogenesis and prenatal diagnosis and review of the literature

The Noonan syndrome (NS) is a true multiple congenital anomalies (MCA) syndrome with numerous manifestations. An association with lymphedema has been noted, but its pathogenesis is not fully understood. Nine new cases and a review of the literature explore the role of lymphedema in NS, including its pathogenesis, presentations, and phenotypic effects. Consideration is given to developmental stage at time of onset, chronicity, resolution, and anatomic site. It appears likely that lymphedema is a much more frequent concomitant in NS than previously realized. The major source of lymphedema in NS appears to be a presently undefined dysplasia of lymphatic vessels of unknown cause. Further study of lymphedema may provide an understanding of its role in shaping the NS phenotype. Comparison with other MCA syndromes and animal models is made in this regard. Relevance to prenatal diagnosis and treatment is discussed.     

Recent progress towards a molecular understanding of Marfan syndrome

Marfan syndrome (MFS) is a systemic disorder of the connective tissue that is inherited as an autosomal dominant trait and which displays variable manifestations in the ocular, skeletal, and cardiovascular systems. These pleiotropic manifestations are accounted for by mutations in fibrillin-1, the building block of extracellular microfibrils. During the past 10 years, we have witnessed significant progress in delineating the pathological events responsible for the manifestations of MFS. Much of this progress has been based on the creation and analysis of fibrillin-1 mutant mouse lines that faithfully recapitulate the spectrum of clinical severity of MFS. These studies have established the critical contribution of fibrillin-1 deficiency to disease progression through altered cell-matrix interactions and dysregulated TGF-beta signaling. As a result, our definition of MFS as the prototypical structural disorder of the connective tissue has changed to that of a developmental abnormality with broad and complex effects on the morphogenesis and function of multiple organ systems. Importantly, new biological targets have emerged that may yield exciting new opportunities for the development of productive treatment strategies in MFS.     

Implementation of genomic arrays in prenatal diagnosis: The Belgian approach to meet the challenges

After their successful introduction in postnatal testing, genome-wide arrays are now rapidly replacing conventional karyotyping in prenatal diagnostics. While previous studies have demonstrated the advantages of this method, we are confronted with difficulties regarding the technology and the ethical dilemmas inherent to genomic arrays. These include indication for testing, array design, interpretation of variants and how to deal with variants of unknown significance and incidental findings. The experiences with these issues reported in the literature are most often from single centres. Here, we report on a national consensus approach how microarray is implemented in all genetic centres in Belgium. These recommendations are subjected to constant re-evaluation based on our growing experience and can serve as a useful tool for those involved in prenatal diagnosis.     

唐氏综合征的无创产前诊断研究进展

唐氏综合征是最常见的染色体非整倍体遗传病,该病尚无有效治疗手段,出生干预是预防该病的有效措施。传统的产前筛查与产前诊断均具有一定的缺陷,无创产前诊断是未来发展的趋势。本文从母血胎儿细胞、母血胎儿游离DNA、母血胎儿游离RNA三个角度对目前唐氏综合征的无创产前诊断研究作一综述,以期对相关领域的研究发展有所帮助。