Kennedy病两个家系的临床表型、基因型和遗传特征分析

目的 分析两个Kennedy病家系的临床表型、基因型和家系特征.方法 收集Kennedy病患者的临床资料,用基因分析的方法 ,明确患者及家族成员雄激素受体基因第1外显子CAG序列的重复数.结果 A家系4代共58人,先证者39岁隐袭起病.B家系5代共61人,有两例患者分别于39岁、41岁缓慢起病.3例患者均以下运动神经元损害为特征,都出现了雄激素不敏感综合征的相关表现.血清肌酶呈轻中度升高;肌电图呈广泛前角损害;肌肉活检示神经源性肌萎缩;雄激素受体基因第1外显子中CAG重复数分别为49、48、47.两个家系的遗传方式均为X连锁隐性遗传.结论 Kennedy病多为中年男性隐袭起病,主要表现为延髓肌和脊髓肌的萎缩和无力,基因分析有助于对本病的确诊,并可明确携带者,以进行遗传咨询及产前诊断.     

Kennedy病两个家系的临床表型、基因型和遗传特征分析

目的 分析两个Kennedy病家系的临床表型、基因型和家系特征.方法 收集Kennedy病患者的临床资料,用基因分析的方法 ,明确患者及家族成员雄激素受体基因第1外显子CAG序列的重复数.结果 A家系4代共58人,先证者39岁隐袭起病.B家系5代共61人,有两例患者分别于39岁、41岁缓慢起病.3例患者均以下运动神经元损害为特征,都出现了雄激素不敏感综合征的相关表现.血清肌酶呈轻中度升高;肌电图呈广泛前角损害;肌肉活检示神经源性肌萎缩;雄激素受体基因第1外显子中CAG重复数分别为49、48、47.两个家系的遗传方式均为X连锁隐性遗传.结论 Kennedy病多为中年男性隐袭起病,主要表现为延髓肌和脊髓肌的萎缩和无力,基因分析有助于对本病的确诊,并可明确携带者,以进行遗传咨询及产前诊断.     

Kennedy病家系的临床及分子遗传学研究

目的 对Kennedy病家系进行临床表型和雄激素受体(androgen receptor,AR)基因突变分析.方法 收集Kennedy病家系2例患者和6例家系成员,对先证者进行神经系统查体,常规检测神经电生理、肌电图、血清肌酸激酶(creatine kinase,CK).抽取8例样本的外周静脉血,提取基因组DNA,PCR扩增AR基因第1号外显子中的CAG重复片段,PCR产物经1.5％琼脂糖凝胶电泳,男性样本进行DNA直接测序.通过毛细胞电泳片段分析技术明确患者及家系成员AR基因第1外显子CAG序列的重复数.结果 2例患者肌电图均显示感觉、运动神经受累及,血清CK均增高,经AR基因CAG重复序列分析,2例患者(Ⅲ1和Ⅲ3)CAG的重复数分别为58次和54次,并检出了4例女性携带者(Ⅱ1、Ⅱ3、Ⅲ5和Ⅳ1),Ⅱ1携带者CAG的重复数为22/58次,Ⅱ3携带者CAG的重复数为22/54次,Ⅲ5携带者CAG的重复数为24/54次,Ⅳ5携带者CAG的重复数为20/61次,2例表型正常男性成员的CAG的重复数均为24次.结论 CAG重复在本家系中存在不稳定遗传.基因诊断可作为Kennedy病诊断的可靠依据.Kennedy病患者进行AR基因突变检测可帮助家系成员进行遗传咨询,对该病的治疗和预防有重要意义.     

一个视网膜色素变性家系的视紫红质基因突变分析

目的　确定常染色体显性遗传视网膜色素变性家系的致病基因及其突变位点,并研究其临床表型。方法　对一个常染色体显性遗传视网膜色素变性(autosomal dominat retinitis pigmentosa,ADRP)家系成员进行了视力、视野及眼底镜检查,并对该家系中先证者进行了视网膜电流图分析。应用聚合酶链反应和直接测序技术,对该家系的所有现存人员的视紫红质基因的外显子进行测序分析。结果　该家系的2 5名成员中12例患者有视紫红质基因(rhodopsin,RH O)的5 12 C>T(P171L)突变,均呈杂合子,该错义突变使密码子171由CCA变成CTA。而未受累者的视紫红质基因表现为野生型。该家系患者的临床表现为5～6岁时出现夜盲,在2 0～30岁逐渐出现视力和视野损害,并先后在4 0～5 0岁前后失明,其中2例患者并发青光眼,先证者的闪烁视网膜电图呈熄灭型。结论　视紫红质基因RH O的一种已知突变5 12 C>T(P171L)是该家系的病因。与国外相同的基因突变类型相比较,该家系发病早、病情进展快、视功能损害较重。     

一个先天性头皮单纯少毛症家系的临床表型及CDSN基因突变分析

目的 通过对1个先天性头皮单纯少毛症(hypotrichosis simplex of the scalp,HSS)家系的临床特征调查及CDSN基因突变分析,以确定该家系的疾病类型和致病基因并建立产前诊断的方法.方法 经家系调查及临床检查确定疾病类型;抽取3例患者及7名正常家系成员和100名正常对照的外周血提取基因组DNA,PCR扩增CDSN基因的第1、2外显子,用直接双向测序、BLAST比对进行突变分析.结果 家系中3例患者均表现为先天性头皮单纯少毛症,呈常染色体显性遗传;在3例患者的CDSN基因第2外显子cDNA序列发现717C＞G无义杂合突变(Y239X),正常家系成员和对照中均未发现该突变.结论 CDSN基因Y239X无义突变是该家系先天性头皮单纯少毛症的致病突变,此突变是首次在中国HSS疾病人群中报道.     

男性不育症患者X染色体雄激素受体基因外显子1、3、4状态筛选研究

目的研究雄激素受体（androgen receptor,AR）基因与特发无精症之间的关系。方法运用分子生物学方法分别检测35名无精症患者和20名对照组正常男性雄激素受体基因的3个功能区的DNA片段,结果实验组患者和正常男性AR外显子1中（CAG）n重复数在11~27之间,两组无显著差别,35例无精症患者用PCR扩增出雄激素受体外显子3（exon3）片段35例（100%）和外显子4（exon4）片段34例（97.15%）,20名正常已生育男性扩增出AR外显子3（exon3）片段20例（100%）和外显子4（exon4）片段20例（100%）。结论（CAG）n基因多态性与男性精子生成障碍无相关性,exon4缺失通过影响靶细胞核的类固醇激素-受体结合物数量在精子发生中的作用需进一步探讨。     

一种导致完全性雄激素不敏感综合征的AR基因移码突变的鉴定

目的 对1个男性假两性畸形完全性雄激素不敏感综合征的家系雄激素受体(androgen receptor,AR)基因进行突变检测,并分析其致病原因.方法 用PCR扩增及DNA测序等技术分析男性假两性畸形先证者候选基因AR的外显子及外显子内含子接头序列,根据检测到的突变位点情况,检测患者及其家系其他成员的相应DNA区段的碱基序列.结果 先证者及其家庭成员共3例患者均为AR基因1910delA的移码突变.其母亲为AR基因突变杂合子,是此疾病的携带者.该突变导致AR基因的N637I(AAU→AUC)、L638*(CTG→TGA)改变,导致AR蛋白283个氨基酸的截短.正常人群未发现该移码突变,该突变尚未见文献报道.结论 基因水平确定了该家系为AR基因突变引起的完全性雄激素不敏感综合征男性假两性畸形家系,同时发现了1种AR基因病理性新突变.     

男性不育的遗传学研究及在ICSI中的意义

目的在细胞遗传学基础上,建立和应用一套检测Y染色体微缺失和雄激素受体基因外显子A突变的分子诊断方法,以便研究男性不育发病机制,为临床辅助生殖技术提供遗传咨询。方法对139例原发不育患者采用外周血染色体G显带、C显带技术,并选择其中40例应用多重PCR和PCR-SSCP银染进行DAZ基因及雄激素受体基因外显子A突变检测。结果139例原发不育患者G、C显带发现54例染色体核型异常,3例DAZ基因缺失,5例雄激素受体基因外显子A发生点突变。结论通过细胞遗传学检查和DAZ基因及雄激素受体基因外显子A突变检测,从遗传学角度探讨了男性不育的病因,对卵浆单精子显微注射技术提供了理论依据。     

浙江沿海一家系脊髓小脑性共济失调的基因突变检测与临床表现

目的 探讨浙江沿海脊髓小脑性共济失调的基因突变检测与临床表现.方法 对该家系18例患者的临床表现、头颅MRI等辅助检查资料分析,并与10名家系中未发病成员及12名非血缘的健康人进行SCA31MJD基因CAG三核苷酸重复数目比较.结果 家系18例患者均为SCA3/MJD型,同时检测出家系中未发病对照组有2例为SCA31MJD型基因携带者.产物测序结果家系对照组与健康对照组CAG重复数为14～27次;SCA患者CAG重复数为67～82次;SCA3/MJD携带者CAG重复数为28～45次.在现存三代18例患者中,每代均有患者,男女均受累,起病年龄平均38岁,以行走不稳、动作笨拙和言语含糊为突出表现,MRI检测结果小脑、脑干明显萎缩.结论 在我国沿海存在SCA3/MJD家系遗传.临床均以共济失调和构音障碍为突出,CAG重复数目检测可为基因诊断和症状前诊断提供依据.     

雄激素受体基因（CAG）n微卫星多态性与疾病易感性

雄激素受体(AR)基因第一外显子中含有遗传多态性的(CAG)n微卫星序列,此序列编码AR转录激活区中的多聚谷氨酰胺片段.近年来研究相继证实,AR中的多聚谷氨酰胺重复数与其转录活性负相关,并进而发现该微卫星多态性与前列腺癌、延髓脊髓性肌萎缩、雄激素不敏感综合征、乳腺癌、子宫内膜癌及卵巢癌等多种疾病的发生、发展密切相关.     

Multiple founder effects in spinal and bulbar muscular atrophy (SBMA, Kennedy disease) around the world.

SBMA (spinal and bulbar muscular atrophy), also called Kennedy disease, is an X-chromosomal recessive adult-onset neurodegenerative disorder caused by death of the spinal and bulbar motor neurones and dorsal root ganglia. Patients may also show signs of partial androgen insensitivity. SBMA is caused by a CAG repeat expansion in the first exon of the androgen receptor (AR) gene on the X-chromosome. Our previous study suggested that all the Nordic patients with SBMA originated from an ancient Nordic founder mutation, but the new intragenic SNP marker ARd12 revealed that the Danish patients derive their disease chromosome from another ancestor. In search of relationships between patients from different countries, we haplotyped altogether 123 SBMA families from different parts of the world for two intragenic markers and 16 microsatellites spanning 25 cM around the AR gene. The fact that different SBMA founder haplotypes were found in patients from around the world implies that the CAG repeat expansion mutation has not been a unique event. No expansion-prone haplotype could be detected. Trinucleotide diseases often show correlation between the repeat length and the severity and earlier onset of the disease. The longer the repeat, the more severe the symptoms are and the onset of the disease is earlier. A negative correlation between the CAG repeat length and the age of onset was found in the 95 SBMA patients with defined ages at onset.     

CAG repeat contraction in the androgen receptor gene in three brothers with mental retardation.

We report on three brothers with mental retardation and a contracted CAG repeat in the androgen receptor (AR) gene. It is known that expansion of the CAG repeat in this gene leads to spinal and bulbar muscular atrophy (SBMA or Kennedy disease); however, contracted repeats have not yet been implicated in disease. As the range of the length of CAG repeats in the AR gene, like those of other genes associated with dynamic mutations, follows a normal distribution, the theoretical possibility of disease at both ends of the distribution should be considered.     

Clinical Characteristics and Genotype-Phenotype Correlation of Korean Patients with Spinal and Bulbar Muscular Atrophy

Purpose

Spinal and bulbar muscular atrophy (SBMA) is an X-linked motor neuron disease characterized by proximal muscle weakness, muscle atrophy, and fasciculation. Although SBMA is not uncommon in Korea, there is only one study reporting clinical characteristics and genotype-phenotype correlation in Korean patients.

Materials and Methods

In this study, age at the onset of symptoms, the score of severity assessed by impairment of activities of daily living milestones, and rate of disease progression, and their correlations with the number of CAG repeats in the androgen receptor (AR) gene, as well as possible correlations among clinical characteristics, were analyzed in 40 SBMA patients.

Results

The median ages at onset and at diagnosis were 44.5 and 52.5 years, respectively, and median interval between onset and diagnosis and median rate of disease progression were 5.0 years and 0.23 score/year, respectively. The median number of CAG repeats in the AR gene was 44 and the number of CAG repeats showed a significant inverse correlation with the age at onset of symptoms (r=-0.407, p=0.009). In addition, patients with early symptom onset had slower rate of disease progression.

Conclusion

As a report with the largest and recent Korean cohort, this study demonstrates clinical features of Korean patients with SBMA and reaffirms the inverse correlation between the age at disease onset and the number of CAG repeats. Interestingly, this study shows a possibility that the rate of disease progression may be influenced by the age at onset of symptoms.     

Androgen receptor gene (CAG)n repeat analysis in the differential diagnosis between Kennedy disease and other motoneuron disorders

An increase in the number of (CAG)n repeats in the first coding exon of the androgen receptor (AR) gene has been strongly associated with Kennedy disease (KD) (spinal and bulbar muscular atrophy). This is an X-linked hereditary disorder characterized by motoneuron degeneration occurring in adults together with gynecomastia and hyperestrogenemia. We have performed AR gene molecular analysis in several members of a large family with KD as well as in 25 sporadic patients suffering from heterogeneous motoneuron disease (MND). An increase in the length of the (CAG)n repeats was detected, as expected, in all the affected males and in obligatory carrier females, some of which had minor signs of lower motoneuron involvement. There was only one possible exception, one young male with initial signs of the disease, who had an apparent normal length allele. An increased pathological allele was also found in 3 patients with MND. This indicates that the analysis of (CAG)n repeats of the AR gene plays a role in the differential diagnosis of this heterogeneous group of neurological diseases. © 1995 Wiley-Liss, Inc.     

Founder effect in spinal and bulbar muscular atrophy (SBMA) in Scandinavia

We haplotyped 13 Finnish, 10 Swedish, 12 Danish and 2 Norwegian SBMA (spinal and bulbar muscular atrophy, Kennedy disease) families with a total of 45 patients and 7 carriers for 17 microsatellite markers spanning a 25.2 cM region around the androgen receptor gene on chromosome Xq11-q12 in search of a genetic founder effect. In addition, the haplotypes of 50 Finnish, 20 Danish and 22 Swedish control males were examined. All the Scandinavian SBMA families shared the same 18 repeat allele for the intragenic GGC repeat, which was present in only 24% of the controls. Linkage disequilibrium was also seen for the closest microsatellite markers. In addition, extended haplotypes of the Finnish, Swedish and Danish SBMA families revealed country-specific common founder haplotypes, which over time became gradually shortened by recombinations. No common haplotype was found among the controls. The data suggest that the SBMA mutation was introduced into western Finland 20 generations ago. Haplotype analysis implies a common ancestor for the majority of Scandinavian SBMA patients.     

A mouse model of spinal and bulbar muscular atrophy

Spinal and bulbar muscular atrophy (SBMA) is an adult-onset motor neuron disease, caused by the expansion of a trinucleotide repeat (TNR) in exon 1 of the androgen receptor (AR) gene. This disorder is characterized by degeneration of motor and sensory neurons, proximal muscular atrophy, and endocrine abnormalities, such as gynecomastia and reduced fertility. We describe the development of a transgenic model of SBMA expressing a full-length human AR (hAR) cDNA carrying 65 (AR(65)) or 120 CAG repeats (AR(120)), with widespread expression driven by the cytomegalovirus promoter. Mice carrying the AR(120) transgene displayed behavioral and motor dysfunction, while mice carrying 65 CAG repeats showed a mild phenotype. Progressive muscle weakness and atrophy was observed in AR(120) mice and was associated with the loss of alpha-motor neurons in the spinal cord. There was no evidence of neurodegeneration in other brain structures. Motor dysfunction was observed in both male and female animals, showing that in SBMA the polyglutamine repeat expansion causes a dominant gain-of-function mutation in the AR. The male mice displayed a progressive reduction in sperm production consistent with testis defects reported in human patients. These mice represent the first model to reproduce the key features of SBMA, making them a useful resource for characterizing disease progression, and for testing therapeutic strategies for both polyglutamine and motor neuron diseases.