脊髓小脑共济失调3型的产前诊断方法研究

目的探讨基于羊水细胞培养和毛细管电泳片段分析技术的脊髓小脑共济失调3型(SCA3/MJD)的产前诊断方法。方法对1例孕20周的确诊SCA3/MJD患者及8名孕16~19周的高龄孕妇进行羊膜穿刺术并抽取羊水细胞培养。采用毛细管电泳片段分析技术对MJD1基因内(CAG)n重复序列动态突变进行检测。结果 SCA3/MJD患者胎儿MJD1基因(CAG)n次数为22/78次,胎儿携带其母亲的异常等位基因,诊断为SCA3/MJD。8例高龄孕妇胎儿MJD1基因(CAG)n重复次数13~26次,均在正常范围内。结论羊水细胞培养并毛细管电泳片段分析技术简便,准确,可作为SCA3/MJD产前诊断的可靠方法进一步推广。     

Double-blind crossover trial of trimethoprim-sulfamethoxazole in spinocerebellar ataxia type 3/Machado-Joseph disease

OBJECTIVE: To evaluate the efficiency of a combination of trimethoprim and sulfamethoxazole in patients with spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD). DESIGN: Placebo-controlled, double-blind crossover trial in 22 patients with genetically confirmed SCA3/MJD. Study phases of 6 months were separated by a washout period of 4 weeks. Dosages were a combination of trimethoprim, 160 mg, and sulfamethoxazole, 800 mg, twice daily for 2 weeks, followed by a combination of trimethoprim, 80 mg, and sulfamethoxazole, 400 mg, twice daily for 5.5 months. SETTING: Outpatient department of the Neurological Clinic, Ruhr-University, Bochum, Germany. MAIN OUTCOME MEASURES: Ataxia ranking scale, self-assessment score, static posturography, and results of motor performance testing. Effects on the visual system were studied using the achromatic Vision Contrast Test System and the Farnsworth-Munsell 100-hue test for color discrimination. Physical and mental health were documented using the Medical Outcomes Study 36-Item Short-Form Health Survey. Subgroup analyses assessed the influence of age, sex, age at onset, duration of the disease, phenotype, and CAG repeat length on test performance. RESULTS: Twenty of 22 patients completed the study. Dropouts were due to a rash (placebo phase) and an attempted suicide in a family conflict. Trimethoprim-sulfamethoxazole therapy had no significant effect in SCA3/MJD patients in the short-term analysis (2 weeks) or in the long-term interval (6 months). CONCLUSIONS: In contrast to previous reports that studied smaller groups of patients, treatment with trimethoprim-sulfamethoxazole did not improve the diverse and complex movement disorders caused by SCA3/MJD. Trimethoprim-sulfamethoxazole had no effect on the visual system and cannot be recommended as a continuous treatment for SCA3/MJD patients.     

Dominantly inherited ataxias: lessons learned from Machado-Joseph disease/spinocerebellar ataxia type 3

To date, nearly 30 distinct genetic forms of dominantly inherited ataxia are known to exist. Of these, Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is perhaps the most common in many regions of the world including the United States. This article discusses MJD/SCA3 as a paradigm example of the dominant ataxias, which are collectively known as the spinocerebellar ataxias. Using MJD/SCA3 as a starting point, the article reviews common clinical and genetic features of the SCAs and highlights new insights into molecular mechanisms, especially of the SCAs caused by polyglutamine expansion. Also discussed are current and future therapeutic opportunities for MJD/SCA3 in particular, many of which have relevance to other SCAs.     

Spinocerebellar ataxia type 15

Spinocerebellar ataxia type 15 (SCA15) was first reported in 2001 on the basis of a single large Anglo-Celtic family from Australia, the locus mapping to chromosomal region 3p24.2-3pter. The characteristic clinical feature was of very slow progression, with two affected individuals remaining ambulant without aids after over 50 years of symptoms. Head and/or upper limb action tremor, and gaze-evoked horizontal nystagmus were seen in several persons. MRI brain scans showed predominant vermal atrophy, sparing the brainstem. In 2004, a Japanese pedigree was reported, which displayed very similar clinical features to the original SCA15 family, and which mapped to an overlapping candidate region. These two families might plausibly reflect a locus homogeneity, but for the present this remains an open question.     

Spinocerebellar ataxia type 20

Spinocerebellar ataxia type 20 (SCA20) was reported in 2004 in a single Australian Anglo-Celtic pedigree. The phenotype is distinctive, with palatal tremor, and hypermetric saccades, and early dentate (but not pallidal) calcification in the absence of abnormalities of calcium metabolism. Dysarthria, rather than gait ataxia, was the initial symptom in most, and was typically conjoined with dysphonia, clinically resembling adductor spasmodic dysphonia. The onset of these speech abnormalities was abrupt in some cases. MRI scanning showed mild to moderate pancerebellar atrophy with dentate calcification, with olivary pseudohypertrophy in some cases, in the absence of other brainstem or cerebral changes. Nerve conduction studies were normal. Progression appeared to be slow. SCA20 is probably rare, as despite the distinctive phenotype, only this one pedigree has been described. The locus mapped to the pericentromeric region of chromosome 11 with a LOD score of 4.47, and its candidate region overlaps that of SCA5. It seems probable that these two SCAs may be separate genetic entities, on the basis of their divergent clinical features, but formal proof awaits discovery of one or both responsible genes.     

Cambodian founder effect for spinocerebellar ataxia type 3 (Machado-Joseph disease)

Four families from the same region of Cambodia immigrated to the Pacific Northwest of the United States. All four families have been discovered to have spinocerebellar ataxia type 3 (SCA 3; Machado–Joseph disease) with a similar clinical phenotype. CAG repeat expansions in the ATXN3 gene range from 72 to 77. Mean age of onset has varied from 19 to 44 years and mean age at death of 4 individuals has been 60 years. The prevalence of the various subtypes of SCA varies worldwide from country to country. Neurologists should be alert to the possibility of SCA 3 in Cambodian patients with unexplained cerebellar ataxia.     

Spinocerebellar ataxia type 4

The spinocerebellar ataxias (SCAs) with autosomal dominant inheritance are a clinically and genetically heterogeneous group of neurodegenerative disorders. To date 24 different loci have been identified for these conditions. A locus at chromosome 16q22.1 co–segregates with the disease phenotype in families of Scandinavian, Japanese and German origin. The corresponding SCA4 locus was narrowed down to 7.94 Mb for the two European and to 1.25 Mb for Japanese pedigrees. Unfortunately, because of the phenotypic differences between patients from Japan and Europe it is not possible to decide if SCA families linked to chromosome 16q22.1 share a common disease genotype or not. To look for mutations in the German family we screened 34 candidate genes in a 3.69 cM region. With the exception of two cSNPs, no segregation of DNA variations with the disease phenotype was found.     

Spinocerebellar ataxia type 3 presenting with writer's cramp without ataxia

Aim of the study: Spinocerebellar ataxia type 3 is the most common cause of autosomal dominant inherited ataxia worldwide.

Material and methods: Clinically, it exhibits wide phenotypic variability. Presentation as isolated dystonia is exceptional.

Results: Here, the case of a woman with writers cramp without ataxia is presented as a paucisymptomatic manifestation of this disease.

Conclusions: This association has not been described to date and extends the clinical variability of the disease.     

Molecular and clinical correlations in spinocerebellar ataxia type 3 and Machado-Joseph disease

The autosomal dominant spinocerebellar ataxias are clinically and genetically a heterogeneous group of neurodegenerative disorders. Genetic studies have classified some of these disorders based on the mapping of their respective genes. The gene for Machado-Joseph disease, one type of spinocerebellar ataxia, has been mapped to the long arm of chromosome 14q24.3-ter. The gene for another spinocerebellar ataxia, which is clinically distinct from Machado-Joseph disease, has been also localized to the same region on 14q and has been named type 3 spinocerebellar ataxia. Recently, expansions of a CAG trinculeotide repeat in a novel gene on chromosome 14q32.1 were shown in 11 patients affected with Machado-Joseph disease. In this study, we analyzed the DNA samples from 103 individuals representing 42 independent families with dominantly inherited ataxia to determine whether any had the Machado-Joseph disease mutation. The Machado-Joseph disease CAG expansion was detected in 5 of these 42 families. Sixteen affected individuals displayed a normal allele containing 14 to 31 CAG repeats and an expanded allele ranging between 66 and 79 CAG repeats. Seven asymptomatic individuals showed an allele ranging between 67 and 80 CAG repeats. Two of these families had a phenotype consistent with Machado-Joseph disease while the other 3 had clinical features of type 3 spinocerebellar ataxia. These data suggest that a single locus at 14q32.1 is responsible for two forms of spinocerebellar ataxia, spinocerebellar ataxia type 3 and Machado-Joseph disease, and that this locus may account for approximately 11% of this group of dominantly inherited ataxias.     

Age related axonal neuropathy in spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD)

To identify determinants of peripheral involvement in spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) the influence of CAG repeat length, age of onset, disease duration and age on the results of nerve conduction studies was analysed in 58 patients with SCA3/MJD. Patients with SCA3/MJD showed marked reduction of compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) amplitudes indicating axonal neuropathy of both motor and sensory fibres. In addition, there was moderate slowing of nerve conduction suggestive of mild peripheral demyelination. Multivariate regression showed that CMAP and SNAP amplitudes decreased with age, but were not affected by CAG repeat length, age of onset, or disease duration. The age related decline of CMAP and SNAP amplitudes in SCA3/MJD was greater than in normal subjects. The data suggest that the degree of peripheral damage in SCA3/MJD does not depend on CAG repeat length, age of onset, or disease duration, but is mainly related to the time period over which the SCA3/MJD mutation exerts its effect.     

Spinocerebellar ataxia type 3 phenotypically resembling parkinson disease in a black family

BACKGROUND: Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), can present with parkinsonism. However, classically, atypical features, including pyramidal and cerebellar signs, peripheral neuropathy, and/or anterior horn cell dysfunction, are also seen. Levodopa responsiveness is unusual in this disorder. OBJECTIVE: To determine the cause of apparent parkinsonism suggestive of Parkinson disease (PD) in a large family of African origin. METHODS: We studied a large family in which apparent autosomal dominant parkinsonism suggestive of PD occurs in order to find the causal genetic mutation. Affected and unaffected family members were screened for the presence of a pathogenic expansion at the MJD/SCA3 locus using a polymerase chain reaction polyacrylamide gel electrophoresis-based assay. RESULTS: Three of the 4 individuals who were examined have a phenotype reminiscent of PD. Specifically, they have at least 2 of the cardinal features, are levodopa responsive, and have no atypical features. All affected family members were shown to possess pathogenic expansions in the MJD/SCA3 gene. CONCLUSIONS: Parkinsonism suggestive of PD due to MJD/SCA3 has not been previously reported, to our knowledge. However, atypical, though also levodopa-responsive, parkinsonism has been previously reported to occur in African American families, suggesting that that this phenotype is associated with African ancestry. In this regard, it is perhaps significant that all the individuals with parkinsonism have relatively low numbers of repeats (normal, 16-34; pathologic, 60-84). In families in which linkage analysis is being performed to determine a locus for autosomal dominant parkinsonism suggestive of PD, evaluation for the MJD/SCA3 mutation is indicated.     

Vestibulo-ocular arreflexia in families with spinocerebellar ataxia type 3 (Machado-Joseph disease)

OBJECTIVE: To identify the presence of vestibulo-ocular arreflexia in patients with Machado-Joseph disease (MJD), which can easily be diagnosed at the bedside. METHODS: Seven patients with MJD from five unrelated families and 11 patients with sporadic or hereditary cerebellar ataxia other than MJD underwent a detailed neuro-otological and oculomotor examination. Six MJD and five non-MJD patients also underwent electro-oculographic recordings and caloric tests. RESULTS: Gaze evoked nystagmus, smooth pursuit, and saccade abnormalities were found in both MJD and non-MJD patients. However, in all seven MJD patients but in none of the non-MJD patients, sudden passively induced head thrust to both sides elicited pathological corrective catch-up saccades, indicating bilateral loss of the horizontal vestibulo-ocular reflex. This was further confirmed in six MJD patients who had absent vestibular response to both a standard caloric test and ice water ear irrigation. Nystagmus was induced by standard caloric irrigation in all non-MJD patients examined. There was no correlation between the loss of vestibular function and the severity of cerebellar impairment. CONCLUSIONS: The presence of vestibulo-ocular arreflexia, as measured by the head thrust test in a patient with dominant cerebellar ataxia, strongly suggests the diagnosis of MJD.     

中国大陆脊髓小脑型共济失调三型/马查多-约瑟夫病女性患者的产前诊断：个案报告

Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is a progressive, currently untreatable and ultimately fatal ataxic disorder that belongs to the group of neurological disorders known as CAG-repeat or polyglutamine diseases. Here, we present the first prenatal diagnosis of SCA3/MJD in mainland China in a woman who was known to carry an expanded CAG-trinucleotide repeat in the MJD1 gene. After evaluating motivation and psychological tolerance of the couple, amniocentesis was performed after 14 weeks of gestation. Polymerase chain reactions followed by T-vector cloning and direct sequencing were employed to evaluate the CAG-repeat number of the fetal MJD1 gene. We identified a truncated CAG expansion of 78 repeats in the MJD1 gene of the fetus compared with 81 repeats in his mother.     

Non-movement disorder heralds symptoms of Machado-Joseph disease years before ataxia.

We describe three patients with the Machado-Joseph disease (MJD) genetic abnormality who had non-movement disorder neurological symptoms or signs that preceded the gait ataxia by several years. This implies that some clinical manifestations other than ataxia may be considered part of the herald symptoms of MJD, especially in the setting of a positive family history.     

New insights into the pathoanatomy of spinocerebellar ataxia type 3 (Machado-Joseph disease)

PURPOSE OF REVIEW: This review summarizes recent neuropathological findings in spinocerebellar ataxia type 3 and discusses their relevance for clinical neurology. RECENT FINDINGS: The extent of the spinocerebellar ataxia type 3 related central nervous neurodegenerative changes has been recently systematically investigated in a series of pathoanatomical studies. These studies showed that the extent of the central nervous degenerative changes of spinocerebellar ataxia type 3 has been underestimated so far. The newly described pattern of central nervous neurodegeneration includes the visual, auditory, vestibular, somatosensory, ingestion-related, dopaminergic and cholinergic systems. These pathological findings were correlated with clinical findings and explain a variety of the spinocerebellar ataxia type 3 symptoms observed in clinical practice. SUMMARY: Systematic pathoanatomical analysis of spinocerebellar ataxia type 3 brains helps to understand the structural basis of this neurodegenerative disease and offers explanations for a variety of disease symptoms. This better understanding of the neuropathology of the condition has implications for the treatment of spinocerebellar ataxia type 3 patients and represents a basis for further biochemical and molecular biological studies aimed at deciphering the pathomechanisms of this progressive ataxic disorder.     

Spinocerebellar ataxia type 1 in Russia

Spinocerebellar ataxia type 1 (SCA1) is one form of autosomal dominant cerebellar ataxia (ADCA) caused by trinucleotide (CAG) repeat expansion within a mutant gene. We investigated 25 patients from 15 Russian ADCA families for SCA1 mutation and found an expanded CAG repeat in 5 families. Mutant chromosomes contained 41–51 CAG repeats (mean 46.1, SD 3.1), and normal chromosomes displayed 21–27 repeat units (mean 24.7, SD 1.3). Progressive cerebellar ataxia in our series of SCA1 patients was very commonly associated with dysarthria (in all cases) and pyramidal signs (in 10 of 11 cases). In three patients from one family we found optic atrophy, which has never been described before in genetically proven cases of SCA1. We observed no specific clinical features distinguishing SCA1 from non-SCA1 patients. In contrast to the high frequency of SCA1 in our series, we found no patients with Machado-Joseph disease, another form of ADCA caused by expanded CAG repeat.     

Degeneration of the external cuneate nucleus in spinocerebellar ataxia type 3 (Machado-Joseph disease)

Owing to its anatomical connections, the external cuneate nucleus (ECU) plays a crucial role in processing proprioceptive input from the upper trunk and upper limbs. Here, we studied this dorsal column nucleus post-mortem in five individuals with clinically diagnosed and genetically confirmed spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease, who had manifested upper trunk and upper limb ataxia. Polyethylene glycol-embedded 100-microm sections stained for lipofuscin pigment and Nissl material, as well as paraffin-embedded Nissl-stained thin sections, revealed serious neuronal loss in the ECU of all five SCA3 patients. As observed in other affected central nervous system structures, the ECU of these individuals displayed an astrogliosis, and some of the few surviving neurons harbored one or even two ataxin-3-immunopositive intranuclear inclusion bodies. The findings of the present study suggest that (1) the ECU is among the consistent targets of the degenerative process underlying SCA3 and (2) interruption of the proprioceptive pathway at the level of the ECU contributes significantly to upper limb and trunk ataxia in SCA3 patients.     

Presumed rapid eye movement behavior disorder in Machado-Joseph disease (spinocerebellar ataxia type 3).

Rapid eye movement behavior disorder (RBD) is a recently recognized sleep disorder in which patients are occasionally not paralyzed during the dream portions of sleep. When not idiopathic, this state has been associated primarily with parkinsonian conditions but also with a small number of medications and other neurodegenerative disorders. Dopamine deficiency may play a role in some patients. This report describes the occurrence of a syndrome that appears to be RBD in 6 of 7 patients followed with Spinocerebellar ataxia type 3 (Machado-Joseph disease). Polysomnography was normal in 1 patient. Two of these patients had had single photon emission computed tomographic imaging of the dopamine transporter 1 year previously.