家族性局灶节段性肾小球硬化一家系相关基因连锁分析

目的 对1个家族性局灶节段性肾小球硬化（FFSGS）家系的临床表型进行连锁分析,并对国内外已知的4个基因进行排除性定位。 方法 调查该家系成员的临床资料。应用两点连锁分析方法,在已知的FFSGS遗传的相关基因WT1、TRPC6、CD2AP、NPHS2所在染色体区域,选取9个微卫星遗传标记（STR）进行连锁分析。 结果 该FFSGS家系的遗传方式为常染色体显性遗传。19名家系成员中1例已进展至终末期肾病（ESRD）;4例尿检异常成员中2例病理明确诊断为FSGS;Ⅲ9和Ⅲ15患者发病年龄较早,分别为10岁和13岁;第Ⅰ和第Ⅱ代的患者均为25岁以后发病。用D1S196、D1S218、D1S238、11S935、D11S898、D11S908、D11S1986、D6S936、D6S1566等9个STR对该家系进行NPHS2、CD2AP、TRPC6和WT1基因的两点连锁分析,测得各个标记位点在重组率θ=0时,最大优势对数（LOD） 值为0.32 (D11S1986),不支持连锁。 结论 该FFSGS家系遗传方式为常染色体显性遗传。已知基因NPHS2、WT1、TRPC6、CD2AP不是该家系的致病基因。     

福建省两个汉族瘢痕疙瘩家系易感基因位点与染色体2q23的连锁分析

目的：探讨福建省两个汉族瘢痕疙瘩家系易感基因位点是否与2q23存在连锁关系。方法：从来自福建省2个汉族瘢痕疙瘩家系中选出26名具有较高遗传学研究意义的成员作为研究对象,采集他们的外周静脉血样,提取基因组DNA,参照国外最近相似研究的方法,在染色体2q23上选取已知的6个最大两点LOD值的微卫星为遗传标记,经PCR扩增,产物基因分型,再进行连锁分析。结果：在重组率θ=0时,这些微卫星标记的两点LOD值都小于-2;在重组率θ=0.05时,它们的两点LOD值均小于-1;可以否定这些标记与2q23的连锁关系。结论：本研究发现福建省两个汉族瘢痕疙瘩家系的易感基因位点不在染色体2q23上的遗传学证据,说明瘢痕疙瘩易感基因位点存在异质性。     

中国汉族瘢痕疙瘩家系易感基因位点的定位分析研究

目的 定位中国汉族瘢痕疙瘩家系的易感基因位点.方法 采集2个4代发病的中国汉族瘢痕疙瘩大家系51例成员的外周静脉血样.提取基因组DNA;假定Fas基因为该家系致病基因的候选基因位点.选取位于10q23.31上Fas基因周围共约10Mbp范围内与细胞凋亡障碍有关的已知基因相邻的微卫星标记D10S1687、D10S1765、D10S1735和D10S1562,对这些微卫星位点进行PCR扩增,产物片断基因分型,再进行连锁分析.结果 在重组率θ=0～0.5时,这些微卫星标记的两点LOD值绝大部分都小于1,排除连锁关系存在.结论 研究发现中国汉族瘢痕疙瘩家系易感基因位点不在染色体10q23.31区域.     

IgA肾病发病机制:分子遗传学研究进展

IgA肾病是多基因多因素参与的复杂性疾病。遗传因素参与IgA肾病的发病和进展。IgA肾病领域的遗传学研究包括以家系为基础的连锁分析和以散发病例为基础的关联分析。连锁分析发现6q22-23、4q26-31、17q12-22和2q36与家族性IgA肾病连锁,但至今未明确致病基因。早年的关联分析以候选基因关联分析为主,北京大学肾脏病研究所采用候选基因关联分析的研究方法,在国际上首次报告了糖基化关键酶的编码基因遗传多态性与IgA肾病易感性的关联。近年来,全基因组关联分析研究(GWAS)的开展发现了5个与IgA肾病发病相关联的遗传区段,包括与获得性免疫相关的MHC区域,与天然免疫相关的8p23,17p13和22q12区域,以及与补体调控相关的1q32区域。GWAS研究带给我们海量数据的同时,也为后GWAS时代带来了许多的机遇和挑战。     

中国人群瘢痕疙瘩家系与染色体 2q23 和 7p11 的连锁分析

目的探讨中国人群瘢痕疙瘩家系是否与2q23和7p11存在连锁关系。方法选择两个中国人群瘢痕疙瘩大家系,从中共选出51名成员,采集其外周静脉血样,提取基因组DNA;参照国外最近相似研究的文献报道,在染色体2q23和7p11上,分别选取6个和4个微卫星标记,经多重PCR扩增,产物片断基因分型,再进行连锁分析。结果在重组率θ=0时,这些微卫星标记的两点LOD值绝大部分都小于-2,排除连锁关系存在。结论本研究首次发现了中国人群瘢痕疙瘩家系的易感基因位点不在染色体2q23和7p11上的遗传学证据,说明瘢痕疙瘩易感基因位点存在异质性。     

中国人群瘢痕疙瘩家系与染色体 2q23 和 7p11 的连锁分析

目的 探讨中国人群瘢痕疙瘩家系是否与2q23和7p11存在连锁关系.方法 选择两个中国人群瘢痕疙瘩大家系,从中共选出51名成员,采集其外周静脉血样,提取基因组DNA;参照国外最近相似研究的文献报道,在染色体2q23和7p11上,分别选取6个和4个微卫星标记,经多重PCR扩增,产物片断基因分型,再进行连锁分析.结果 在重组率θ=0时,这些微卫星标记的两点LOD值绝大部分都小于-2,排除连锁关系存在.结论 本研究首次发现了中国人群瘢痕疙瘩家系的易感基因位点不在染色体2q23和7p11上的遗传学证据,说明瘢痕疙瘩易感基因位点存在异质性.     

福建省两个汉族瘢痕疙瘩家系易感基因位点与染色体7p11的连锁分析

目的：探讨福建省两个汉族瘢痕疙瘩家系易感基因位点是否与7p11存在连锁关系。方法：从来自福建省2个汉族瘢痕疙瘩家系中选出26名具有较高遗传学研究意义的成员作为研究对象,采集他们的外周静脉血样,提取基因组DNA,参照国外最近相似研究的方法,在染色体7p11上选取已知的4个最大两点LOD值的微卫星为遗传标记,经PCR扩增,产物基因分型,再进行连锁分析。结果：在重组率Θ=0～0．1时,这些微卫星标记的两点LOD值都小于-2,排除这些标记与染色体7p11的连锁关系。结论：本研究发现福建省两个汉族瘢痕疙瘩家系的易感基因位点不在染色体7p11上的遗传学证据,说明瘢痕疙瘩易感基因位点存在异质性。     

华人遗传性混合息肉病综合征患者单倍型及遗传连锁分析

目的探讨华人遗传性混合息肉病综合征(HMPS)患者基因单倍型定位与公认Ashkenazi家系(SM96)是否一致。方法从31个家系成员外周血标本中提取基因组DNA,多重PCR扩增4个微卫星标记D15S1010、D15S1007、ACTC和D15S118。采用单倍型和遗传连锁分析方法,验证人染色体15q13区域2.8cM范围内遗传标记是否与致病基因连锁。结果12号家系中该病的单倍型在一个患病个体无标记连锁,同时2号家系未发现该病的单倍型。ACTC标记两点及多点遗传连锁分析最大对数优势记分LODs分别为0.20(θ=0.3)和-5.0。结论单倍型及遗传连锁分析提示,Ashkenazi单倍型与华人HMPS无关,两者存在遗传背景的差异性。     

家族性IgA肾病的诊断及临床特征——并一4代40名成员家系分析

目的：复习国内外文献,明确遗传性IgA肾病的诊断标准,并对一较完整的4代40例家族性IgA肾病家系的临床及遗传特征进行对照分析。方法：对所获家系详细调查成员组成,并对现存的家系成员进行血常规、尿常规、肝肾功能、肾脏超声检查以及皮肤活检,排除其他遗传性疾病以及继发性肾脏病;对6例患者行肾脏活检了解病理类型,对照国内外家族性IgA肾病的诊断标准,明确该家系的诊断、了解其遗传特征。结果：目前国际上对于家族性IgA肾病的诊断分为4种情况：（1）可以明确诊断FIgAN;（2）疑似可能的FIgAN;（3）明确排除FIgAN;（4）无法确定的FIgAN。根据已知该家系的遗传关系绘制家系图,对现存的家系成员临床资料进行分析：27个非婚配家系成员中,12例患病,其中3例发生ESRD,9位成员存在不同程度的镜下血尿、蛋白尿和（或）血肌酐升高,8例因年龄尚小暂不能确定患病状态,需要长期的随访观察其尿检的变化情况。患者中6例行肾活检,3例为IgA肾病,另3例为系膜增殖性肾小球肾炎,电镜结果均未发现基底膜厚度的异常,6例皮肤活检未发现Ⅳ型胶原的缺失,排除了Alport综合征。结论：根据国内外诊断标准,该家系成员可以明确诊断为家族性IgA肾病。FIgAN是IgA肾病的特殊类型,预后较差,应引起临床医生对此疾病的重视,以期尽早的明确诊断及治疗。     

中国汉族一瘢痕疙瘩家系易感基因的定位研究

目的定位中国汉族瘢痕疙瘩家系的易感基因。方法采集1个5代发病的中国汉族瘢痕疙瘩大家系32名成员的外周静脉血样,提取基因组DNA;设定Fas基因为导致该家系发病的一个候选基因,选取位于10q23.31上Fas基因周围共约10Mbp范围内与细胞凋亡障碍或肿瘤发生有关的所有已知基因相邻的微卫星标记D10S1687、D10S1765、D10S1735和D10S1562共4个,对这些微卫星位点进行PCR扩增,产物片断基因分型和连锁分析。结果连锁分析发现微卫星标记D10S1765LODZMAX为1.74,D10S1735LODZMAX为1.51,支持连锁;D10S1562LODZMAX为0.59,不排除连锁;在θ=0.0～0.10时,D10S1687标记的所有LOD值都小于-2,排除连锁。结论我们的研究首次发现了该中国汉族瘢痕疙瘩家系的易感基因可能位于10q23.31上D10S1765与D10S1735两位点间约1Mbp区域的遗传学证据。     

Characterization of a large Lebanese family segregating IgA nephropathy.

BACKGROUND: Familial aggregation of IgA nephropathy (IgAN) suggests that genetic factors contribute to the development of this trait. Because clinical manifestations in IgAN families are often limited to episodic haematuria, large kindreds tractable to linkage analysis have been difficult to identify. METHODS: We identified a large Lebanese-Druze kindred ascertained via an index case with biopsy-documented IgAN. We performed systematic screening of 38 family members and tested linkage to reported IgAN loci. RESULTS: Screening of this family identified 16 affected individuals, including 2 individuals with biopsy-documented IgAN and 14 with chronic renal failure or abnormal urinalyses on at least three separate occasions. This kindred spanned five generations and contained five consanguineous unions. Multigenerational inheritance suggested that autosomal dominant inheritance was most likely. Phenotypic manifestations among affected individuals varied from isolated haematuria to advanced renal failure necessitating transplantation; one instance of IgAN recurrence after transplantation was also documented. Older age was associated with greater severity of disease and higher incidence of renal failure. Parametric and non-parametric analyses with 33 microsatellite markers did not reveal any evidence of linkage to reported IgAN loci on chromosomes 6q22-23, 2q36 and 4q22-31. CONCLUSIONS: We describe one of the largest multigenerational IgAN kindreds reported to date. The high incidence of renal failure among older generations suggests a significant risk of progression to renal failure. We found no evidence of linkage to known loci, suggesting that familial IgAN encompasses multiple subtypes that will require distinction based on genetic or biomarker data.     

The genetics of IgA nephropathy

IgA nephropathy is the most common form of primary glomerulonephritis. Variations in clinical manifestations indicate that a diagnosis of IgA nephropathy encompasses multiple disease subsets that cannot be distinguished on the basis of renal pathology or clinical variables alone. Familial forms of the disease have been reported throughout the world, but are probably under-recognized because associated urinary abnormalities are often intermittent in affected family members. IgA nephropathy has complex determination, with different genes probably causing disease in different patient subgroups. Of the many pathogenic mechanisms reported, defects in IgA1 glycosylation that lead to formation of immune complexes have been consistently implicated. Here, we present the evidence for genetic contributions to the disease, review clinical patterns of familial disease, and summarize some of the most promising genetic studies conducted to date. Linkage-based approaches to the study of familial forms of the disease have identified significant or suggestive loci on chromosomes 6q22-23, 2q36, 4q26-31, 17q12-22 and 3p24-23, but no causal gene has yet been identified. Many interesting, but poorly replicated, genetic association studies have also been reported. We discuss recent developments in analytic tools that should enable genetic studies of sporadic forms of disease by the genome-wide association approach.     

Genome-wide linkage scan of a large family with IgA nephropathy localizes a novel susceptibility locus to chromosome 2q36

IgA nephropathy (IgAN) is the most common glomerulonephritis worldwide and an important cause of ESRD. Familial clustering of cases suggests genetic predisposition to this disease. Two recent genome-wide studies in IgAN have identified a major susceptibility locus on chromosome 6q22 (IGAN1) and two additional loci with suggestive linkage signals on chromosomes 4q26-31 and 17q12-22. A large four-generation family with 14 affected individuals has been clinically ascertained and excluded from linkage to these loci. A genome-wide linkage scan was performed on this family with GeneChip Mapping 10K 2.0 Arrays using an "affected-only" strategy. By nonparametric analysis, two regions of suggestive linkage (multipoint logarithm of odds [LOD] scores >2) were identified on chromosomes 2q36 and 13p12.3. By parametric analysis (assuming an autosomal dominant inheritance, a disease allele frequency of 0.001, phenocopy rate of 0.01, and penetrance of 75%), a significant linkage to chromosome 2q36 (maximum multipoint LOD score 3.47) was found. Nine simple sequence repeat markers then were genotyped in 21 members (included all of the affected individuals), and significant linkage to chromosome 2q36 over a region of 12.2 cM (maximum multipoint LOD score 3.46) was confirmed. Recombination events in two affected individuals, as detected by haplotype analysis, delineated a critical interval of approximately 9 cM (equivalent to approximately 7 Mb) between D2S1323 and D2S362. Taken together, these data provide strong evidence for a novel disease susceptibility locus for familial IgAN.     

IgA肾病合并肾小球基底膜弥漫性变薄的临床特点及COL4A3/COL4A4的基因连锁分析

目的 对IgA肾病合并肾小球基底膜弥漫性变薄(TGBM-IgAN)患者的临床病理情况进行系统研究；并在TGBM-IgAN患者的家系中，初步探讨同薄基底膜肾病(TGBMD)相关基因COL4A3/COL4A4的关系。方法 根据透射电镜下GBM的厚度，以GBM的平均厚度小于250 nm及GBM变薄的范围至少达到50%为诊断GBM变薄的标准，明确GBM弥漫性变薄在散发性IgA肾病患者及肾脏病家族史阳性的患者中所占的比例。将234例IgA肾病患者分成合并GBM弥漫性变薄组(n=30)及正常GBM厚度组(n=204)，比较两组患者的临床和病理特点。应用2号染色体长臂分别与COL4A3/COL4A4基因连锁的微卫星体PAX3及HaeⅢ-酶切限制性多态性片段(RFLP)位点作为多态性遗传标记，对其中3个TGBM-IgAN的家系进行COL4A3/COL4A4基因连锁分析。结果 本研究中IgA肾病GBM正常厚度为(352.43±32.11) nm，TGBM-IgAN的GBM厚度为(205.56±23.48) nm。(1)在家族性IgA肾病患者中，TGBM-IgAN患者所占比例为31.8%(21/66)，明显高于其在散发性IgA肾病中所占比例11%(24/219)；(2)30例TGBM-IgAN患者临床特点:女性为主(20/30)，合并肾脏病家族史比例高，均有血尿，尿蛋白量少，预后较好；(3)3个TGBM-IgAN家系中，2个家系与COL4A3/COL4A4的连锁分析提示与COL4A3/COL4A4基因连锁，LOD值为1.53(θ=0)。结论 家族性TGBM-IgAN明显高于散发性患者，合并GBM弥漫变薄的呈家族聚集性发病的IgA肾病患者家系可能为薄基底膜肾病家系，建议在家族性IgA肾病的定义中应强调电镜下GBM形态和厚度的观察。     

Autosomal dominant progressive nephropathy with deafness: linkage to a new locus on chromosome 11q24

Focal segmental glomerulosclerosis (FSGS) and Alport syndrome (AS) are two major causes of end-stage renal disease (ESRD). A few families with autosomal dominant FSGS have been reported with linkage to chromosome 19q13 or 11q22, while AS is usually linked to mutations in type IV collagen (COL4) subunit genes. A phenotype resembling AS may also be seen with myosin heavy chain-9 (MYH9) gene mutations. This study ascertained a multigeneration family (CHP-177) with clinical aspects of both FSGS and AS where we identified a new locus for the trait. A genome-wide scan was performed with 400 markers, and fine mapping was performed for chromosome 11 markers. Data were analyzed by GENEHUNTER and VITESSE under various models. CHP-177 is a 39-member kindred residing near New Delhi, India, with seven affecteds and showed male-to-male transmission. Two members had ESRD. Renal biopsies showed both FSGS lesions and thin glomerular basement membranes. Five of the affecteds also had sensorineural deafness, which involved both low and high frequency in some members. The AS loci, i.e., COL4A3/COL4A4 and MYH9 (LOD scores: -6.1 and -4.3, respectively) and FSGS loci, on 19q13 and 11q22, were excluded from linkage. A significant evidence of linkage was observed for 11q24 region, with a multipoint LOD (z-score) of 3.2 for marker D11S4464 at theta = 0. The z-1 confidence interval for the linked region spans a genetic distance of 7 cM. This study thus reports an autosomal dominant nephropathy with features of both FSGS and AS in which linkage to currently known loci for such phenotypes was excluded and a new locus on 11q24 was identified. The findings suggest further locus heterogeneity for the autosomal dominant nephropathy phenotype.     

Pathogenesis of IgA nephropathy

Immunoglobulin A (IgA) nephropathy is an immune-complex-mediated glomerulonephritis characterized by the presence of immunoglobulin A deposits in mesangial and paramesangial regions. The patients with IgA nephropathy present with varying clinical symptoms (eg, microhematuria with preserved renal function or progressive deterioration of renal functions resulting in end-stage renal disease). The factors involved in the pathogenetic mechanisms of IgA nephropathy include (1). environmental factors, (2). genetic factors, (3). abnormality of the IgA1 molecule, and (4). various inflammatory mediators. The gene polymorphism studies for human leukocyte antigen (HLA), renin-angiotensin-aldosterone system, and selectin gene clusters, suggest a certain degree of genetic predisposition in patients for IgA nephropathy. Also, the genome-wide screening in familial IgA nephropathy showed linkage of IgA nephropathy to the 6q22-23 chromosome. Besides genetic influence in its pathogenesis, aberrant galactosylation in serum IgA and IgA1 eluted from kidneys with IgA nephropathy has been observed, and conceivably such abnormalities induce the expression of various cytokines, interleukin (IL)-6, platelet-derived growth factor (PDGF), tumor necrosis factor (TNF)-alpha, and transforming growth factor (TGF)-beta1 in the renal cells, which contributes to further glomerular injury. Despite an enormous amount of information available in the literature, further studies are needed to delineate the precise pathogenetic mechanisms involved in primary IgA nephropathy and also to facilitate the development of newer therapeutic interventions.     

Inherited forms of IgA nephropathy

Simplex and multiplex families with IgA nephropathy (IgAN) have been reported from several ethnic backgrounds, providing the strongest evidence of a role for genetic factors in pathogenesis of IgAN. From a phenotypic point of view, familial and sporadic IgAN cannot be differentiated, and the main clinical and histological features are similar. Traditionally, the case-control study design was employed to identify associations between particular candidate genes, for example, HLA antigens the uteroglobin gene and IgAN, giving conflicting results. Recently, a different approach, using linkage analysis, was undertaken by geneticists at Yale University. A 10-cM genome-wide screen was performed in 30 multiplex IgAN pedigrees, and one locus was mapped (IGAN-1) on chromosome 6q22-23. Future study will be focused on the identification of the gene underlying IGAN-1. This will enable us to understand the molecular pathogenetic basis of IgAN.     

Does monosymptomatic enuresis exist? A molecular genetic exploration of 32 families with enuresis/incontinence

OBJECTIVE:s To confirm linkage to microsatellite markers on chromosome 8q, 12q, 13q and 22q in families with nocturnal enuresis/incontinence segregating with an autosomal dominant pattern, and to determine if there is an association between the clinical subtype and these linked loci. PATIENTS AND METHODS: Families with at least three members with nocturnal enuresis in two generations were included in the study. The index patient was > or = 7 years old and had evidence of bladder dysfunction; all other family members were > or = 5 years old. Bladder dysfunction in the index patients was documented by video-urodynamics when indicated. A nycthemeral rhythm of diuresis was documented in all index patients. The clinical diagnosis of all family members was based on a questionnaire on voiding problems and micturition habits, uroflowmetry, measurement of functional bladder capacity and nocturnal diuresis. Linkage was analysed using an autosomal dominant model with a gene frequency equal to 0.05 and a penetrance of 0.9. RESULTS: Thirty-two families with nocturnal enuresis/incontinence (one with four, 25 with three and six with two generations) were included. The mean number of persons included per family was 10 and on average five members were symptomatic. Linkage of nocturnal enuresis to a region on chromosome 22q11 was found in nine families, to 13q13-14 in six and to 12q in four. There was no convincing evidence for linkage to chromosome 8q. Clinical findings in the proband and their family members with possible linkage to a given locus were heterogeneous, and hence no clear genotype/phenotype correlation could be postulated. CONCLUSION: These findings support the hypothesis of the genetic and phenotypic heterogeneity of nocturnal enuresis/incontinence. Putative linkage was confirmed to the same chromosomal loci as in previous studies of 'monosymptomatic' enuresis and different phenotypes were linked to the same loci.     

一汉族瘢痕疙瘩家系的易感基因定位分析研究

目的采用连锁分析方法探讨瘢痕疙瘩(keloid)家系的疾病易感基因与15q22.31-q23及18q21.1区域的连锁关系。方法1个中国东北地区5代keloid家系,采集家系中32名成员的外周血标本提取DNA,选择位于15q22.31-q23及18q21.1区域7个微卫星标记,应用聚合酶链式反应(PCR)得到扩增产物片断,测定PCR产物片段大小,得到每个样本的基因型,运用连锁分析软件Linkage5.11的MLINK程序计算每个标记的LOD值,根据两点间LOD值判断连锁关系。结果D15S108、D15S216、D15S534、D18S363、D18S846五个位点的两点LOD值在重组率为0时均小于-2,可以排除连锁关系,而D18S460、D18S467两位点在重组率θ为0.05和0.10时的两点LOD值均大于1,D18S460在θ=0时大于2,提示此家系keloid易感基因与这两个位点存在一定连锁关系。结论此汉族keloid家系的易感基因可能位于染色体18q21.1区域内,初步确定SMAD2和PIAS2基因为可能的易感基因。     

Genome scan for determinants of serum uric acid variability

Elevated serum uric acid level is associated with obesity, insulin resistance, diabetes, nephropathy, and hypertension. Epidemiologic studies suggest that serum uric acid levels are heritable. We sought to identify chromosomal regions harboring quantitative trait loci that influence serum uric acid in Mexican Americans using data from 644 participants in the San Antonio Family Heart Study. Serum uric acid was found to exhibit significant heritability (0.42) in this population (P = 2 x 10(-7)) after accounting for covariate effects. In addition, genetic correlations between serum uric acid and other cardiovascular risk factors, such as body mass index, waist circumference, systolic BP, and pulse pressure, were identified, suggesting that the genes associated with uric acid level are also associated with these phenotypes. Multipoint linkage analysis identified quantitative trait loci with measurable effects on serum uric acid variability. The highest multipoint logarithm of odds score of 3.3 was found at 133 cM on chromosome 6q22-23, a region that also contains genes that seem to influence familial IgA nephropathy, obesity, BP, insulin resistance, and type 2 diabetes. Given the relationship between uric acid level and these conditions, future studies should investigate potential candidate susceptibility genes found in this region.