Focus on genetic modifiers of polyglutamine diseases / 中华神经科杂志

Polyglutamine (PolyQ) diseases are a group of clinically and genetically heterogeneous neurodegenerative diseases, due to an expanded CAG repeat in a coding region of the respective genes leading to neurodegenerative phenotypes by selective neuronal loss. Overall, only part of variance (50%-70%) in age at onset is explained by (CAG)n length, suggesting genetic modifying factors independent of (CAG)n size may contribute to clinical heterogeneity. Here, the research history of genetic modifiers in polyQ diseases is reviewed, and the major findings and current research status are discussed.

Positive Correlation between Androgen Receptor CAG Repeat Length and Metabolic Syndrome in a Korean Male Population

PURPOSE: In epidemiological studies, there are various associations of androgen receptor (AR) CAG with several diseases or phenotypes. However, the relationship between CAG repeat length and metabolic syndrome (MS) remains unclear, especially in Asian populations. This study was designed to evaluate the relationship between AR CAG repeat length polymorphism and MS in a Korean male population. MATERIALS AND METHODS: We explored the relationship between AR CAG repeat length polymorphism and MS in a Korean male population (n=337) from 2013 to 2014. AR CAG repeat were determined by microsatellite fragment sizing. Components of MS and laboratory data (lipid profile, fasting glucose, and glycated hemoglobin (HbA1c)) were analyzed with AR CAG repeat length. RESULTS: The mean AR CAG repeat length was 22.3±4.7. Sixty-nine men (20.5%) were diagnosed with MS. Men with MS showed significantly longer AR CAG repeat lengths compared with men without MS (26.2 vs. 21.4, p < 0.001). With increasing CAG repeat, the number of components meeting the NCEP criteria increased significantly. AR CAG repeat length was associated significantly with high density lipoprotein (HDL), triglyceride, and HbA1c levels. In the multivariate analysis, CAG repeat length, waist circumference, and levels of HDL were independently associated with MS. (odds ratio (OR)=1.37, 1.19 and 0.90, p < 0.001, 0.045, and 0.001, respectively). CONCLUSIONS: AR CAG repeat length was associated with MS and laboratory test results, such as those for HDL, triglycerides, and HbA1c, in Korean males. Longer CAG repeat length was identified as a risk factor for MS in Korean males.

Clinical features and genetic mutation analysis of spinocerebellar ataxias in Yunnan region / 中华神经科杂志

Objective To identify the specific genotype and analyze clinical features of spinocerebellar ataxias (SCAs) pedigree in the region of Yunnan Province.Methods Fourteen SCAs pedigrees and 183 blood samples of the family members were collected between January 2011 and July 2014 from Department of Neurology,First Affiliated Hospital of Kunming Medical College.Polymerase chain reaction (PCR) amplification,agarose gel electrophoresis and DNA sequencing technologies were utilized to identify the specific genotype of SCAs pedigree.Presymptomatic tests were carried out and the clinical features and genetic test results of patients were carefully analyzed.Results SCA3 was the most common subtype of SCAs in the Han nationality of Yunnan region.Nine of the 14 families were SCA3,only one family was SCA2.Additionally,there were four SCAs families that remained indeterminate.The patients with di-allele mutations (46/77) of SCA3 gene had early onset,rapid progression and serious clinical symptoms.Hereditary SCA3 and autonomic dominant polycystic kidney disease can happen simultaneously in a family.The proband SCA3 gene' s CAG repeat number is 28/76,and repetitions of the mutation allele are in all range.The PKD1 gene exon 23 is found to be in abnormal sequence.Conclusions SCA3 is the most common subtype of SCAs in the Han population of Yunnan region.There are 15/46 incomplete penetrance nutation and 46/77 di-allele mutations.It is possible that di-allele mutations make the disease worse and accelerate clinical course progression.SCA3 and polycystic kidney disease can uncommonly happen simultaneously in a family,which perhaps suggests there are interactions between the two disease-virulence genes.

Myotonic Dystrophy: Accurately Scoring the Boundaries that Define Regions of Triplet Repeat Expansion Mutations.

Aims: Myotonic Dystrophy type 1 (DM1) is an autosomal dominant neuromuscular multi-systemic disorder caused by a CTG triplet repeat expansion mutation in the DMPK gene. The clinical decision points defining the CTG repeat boundaries between normal, premutation and mild disease ranges are poorly characterised with a lack of commercially available sequenced controls. There are no US Food and Drug Administration (FDA) approved tests for DM1 so testing protocols are developed and managed by individual laboratories.Study Design: This paper presents a cross-laboratory exchange scheme between Auckland City Hospital and Concord Hospital, which took place between October 2013 and January 2014, in order to validate the scoring of CTG repeats within the DMPK gene and to build comprehensive allelic libraries. Methodology: Seven samples ranging from 30-59 repeats, spanning the critical clinical decision points, were sequenced to confirm the “true” repeat sizes, and 19 samples were tested by both laboratories using standard and triplet repeat-primed PCR methods. Results: The results showed a very strong correlation between the sequencing results and the standard PCR results for the 7 selected samples with a Pearson correlation coefficient of 0.999 and P = 1.20x10-7. The results from the inter-laboratory comparison also showed a very strong correlation between the diagnostic tests of the two labs with a Pearson correlation coefficient of 0.999 and P = 1x10-29. A paired t-test showed no significant difference between the two laboratories data with a Mean (SD) = 0.263 (0.828), P = .058. Conclusion: This study provides two critical outcomes. The first is that the extrapolations that were used by each of the participating laboratories in determining the number of CTG repeats in the absence of well-characterised controls in the 35-51 repeat range were within their reported margins-of-error. The second outcome is that small regional laboratories can gain confidence in the accuracy of their reported allele calls, specifically around clinically critical decision points, with inter-laboratory exchange studies and in-house sequencing of relevant control samples.

Molecular genetics of a Chinese family with spinocerebellar ataxia / 解放军医学杂志

Objective To study the genotype of the members of a Chinese family with spinocerebellar ataxia (SCA). Methods The peripheral blood samples of 6 patients and 40 asymptomatic people belonged to the family were collected. Referring to the clinical manifestations of the proband and second-generation sequencing results, the CAG trinucleotide repeats of the pathogenic gene ATXN2 were amplified by polymerase chain reaction (PCR). The repeated times of the trinucleotide in normally and abnormally amplified alleles were defined by agarose gel electrophoresis and PCR products sequencing. Results Autosomal dominant heredity was the cause of the SCA in this family. Six out of 46 in the fourth-generation were SCA2 patients, 7 were the carriers of pathogenic allele. The repeated times of CAG trinucleotide were within the normal range in one of the two alleles of ATXN2, but they were in abnormal range in the another one. The repeated times of CAG trinucleotide were 40-46 in abnormal alleles of patients. Conclusion Autosomal dominant heredity SCA2 has been diagnosed in this family caused by the dynamic nutation of CAG trinucleotide repeats, and 7 pathogenic allele carriers in this family were confirmed by genetic diagnosis.

Distribution of five common subtypes of spinocerebellar ataxia in the Korean population

PURPOSE: Spinocerebellar ataxia (SCA) is a genetically heterogeneous disease for which more than 30 subtypes have been identified. However, 5 subtypes, SCA1, SCA2, SCA3, SCA6, and SCA7, account for more than 60% of cases. In this study, we report the distribution of these 5 subtypes in Korean patients. MATERIALS AND METHODS: Six hundred and thirty-eight unrelated patients with a presumptive diagnosis of SCA were included in this study. Trinucleotide (CAG) repeat number (TNR) repeat number was determined using fluorescently labeled primers and fragment analysis. RESULTS: A total of 128 unrelated patients (20.1% of all individuals tested) tested positive for SCA subtypes, including SCA1 (5 patients, 3.9% of those testing positive), SCA2 (38 patients, 29.7%), SCA3 (30 patients, 23.4%), SCA6 (39 patients, 30.5%), and SCA7 (16 patients, 12.5%). The mean copy number of pathogenic TNR alleles was 45+/-8.5 for SCA1, 42+/-3.1 for SCA2, 72+/-5.4 for SCA3, 23+/-1.5 for SCA6, and 50+/-11.4 for SCA7. TNR copy number was inversely correlated with onset age in SCA2, SCA6, and SCA7. CONCLUSION: SCA2, SCA3, and SCA6 are common SCA subtypes in Korean patients and could be screened as a first-line test. Expanded pathogenic allele size was associated with early onset age.

Clinical and genetic study of spinocerebellar ataxias 3 within a consanguinity family / 中华神经科杂志

Objective To investigate the inheritance principle of the expanded GAG repeat allele and the clinical features of spinocerebellar ataxias 3 (SCA3) in a consanguinity family with first cousin marriage.Methods The CAG repeats of SCA3 gene were amplified by means of polymerase chain reaction.Fragment analysis with laser-induced fluorescence in capillary electrophoresis were performed for the positive samples detected by agarose gel electrophoresis.Furthermore,the clinical features were analyzed carefully.Results Fragment analysis revealed that the proband carried 2 alleles with 56 and 72 CAG repeats separately.The proband' s father carried 28 and 66,and the expanded CAG repeat allele inherited from his grandfather.The proband' s mother carried 33 and 56,and the expanded CAG repeat allele inherited from his grandmother.The proband' s son carried 27 and 85 and presented with dystonia besides ataxia.Conclusions The proband' s parents have the common ancestors.Their alleles with expanded CAG repeats probably come from the same allele of their ancestor.The GAG repeat is more unstable in the paternal inheritance than in the maternal inheritance.The 71-year-old asymptomatic family member carry the allele with 56 CAG repeats,which indicates the 56 CAG repeats may be not associated with the disease.The patients within this family have variable clinical features,especially the juvenile-onset case presents with apparent dystonia.

Molecular and clinical study of spinocerebellar ataxia type 17 / 中华神经科杂志

Objective To investigate the clinical features and genetic mutations of spinocerebellar ataxia type 17 (SCA17).Methods The pathological CAG triplet repeat expansions of the SCA3,SCA1,SCA2,SCA6,SCA7,SCA8,SCA12,SCA17 and dentatorubral pallidoluysian atrophy genes were analyzed in 708 probands of autosomal dominant familial SCA and 1 19 sporadic SCA cases.The CAG repeats of TATA-binding protein (TBP) gene were amplified by means of polymerase chain reaction and agarose gel electrophoresis.For the samples with two alleles,fragment analysis based on CEQ8000 sequencer was applied to analyze the CAG repeat numbers.Furthermore,the correlation between clinical features and CAG repeat in the TBP gene was studied carefully.Results The expanded CAG repeats in the TBP gene was detected in 5 cases with 37/50,36/45,38/52,38/53,36/54 separately.And the main clinical manifestations were ataxia and memory impairment.Conclusion These findings indicate that SCA17 might be a rare subtype of SCA in the Chinese population and the clinical features of SCA17 cover a wider spectrum than previously reviewed.

Distribution of CAG repeat number within androgen receptor gene in Chinese Han nationality and its application in genetic diagnosis for Kennedy's disease / 中华老年医学杂志

Objective To investigate the distribution of androgen receptor (AR) gene CAGrepeats in the Chinese Han nationality and its application in genetic diagnosis for Kennedy's disease (KD). MethodsRT-PCR,denaturing polyacrylamide gel electrophoresis (DPAGE) and gene sequencing were conducted for AR gene CAG repetition among 100 healthy controls and 28 patients diagnosed as motorneuron diseases,and the number of the repetition was counted. Results The healthy controls had a range of 15-31 times of CAG repetition,with an average of (23 ± 3) times.Among patients with motoneuron disease,3 cases with CAG repetition for more than 40 times (namely,46,47 and 47 times) were diagnosed as KD.The main clinical manifestations included slow progress of limb weakness,primarily in the proximal lower limbs,fatigue accompanied by myalgia,muscle jumping,muscle atrophy,elevated serum creatine kinase (CK) levels,neurogenic damage revealed by electromyogram (EMG) and androgen insensitivity.Conclusions The incidence of KDmay be underestimated in the Chinese population.Performing genetic diagnosis in patients with motor neuron disease for AR gene can improve clinical diagnosis and avoid misdiagnosis.

The reliability of cloning-sequencing to detect the number of trinucleotide repeats / 中华神经科杂志

Objective Cloning-sequencing is a common method to detect the number of trinucleotide repeats.The aim of the present study is to discuss its reliability.Methods One clinically diagnosed SCA1 patient was recruited in the study.The numbers of CAG repeats in ATXN1 gene were estimated via polymerase chain reaction (PCR) and denaturing polyacrylamide gel electrophoresis (DPAGE).To verify accuracy of CAG numbers estimated, the PCR products were electrophoresed on a 2.5% agarose ge] and separated bands were excised for direct sequencing.Also, the longer separated band underwent cloning-sequencing using a TA cloning kit.Results The patient was identified as SCA1 by DPAGE.After direct sequencing, the numbers of CAG repeats were 26 and 47 in the shorter and longer bands, respectively.However, after cloning-sequencing of the longer band, there are 10 different numbers of CAG repeats, including 50, 47, 46, 41,32, 28, 27, 26, 25 and 24.Furthermore, there are other kinds of trinucleotide repeats, such as CCG, CGG, CTG, CAA and TAT scattered among the CAG repeats.Conclusions It is not reliable to identify the number of trinucleotide repeats by cloning-sequencing alone.To improve the reliability, it is better to combine cloning-sequencing with other methods.

Análisis molecular de los repetidos CAG en pacientes mexicanos con ataxia espinocerebelosa tipo 2 / Molecular analysis of the CAG repeat among patients with Type-2 spinocerebellar ataxia in the Mexican population

Antecedentes: La ataxia espinocerebelosa tipo 2 es causada por la expansión del repetido CAG presente en el exón 1 del gen de la ataxina-2, lo cual origina la incorporación de un segmento de poliglutaminas en la proteína mutante. Métodos: Mediante reacción en cadena de la polimerasa y electroforesis capilar se determinó el número de repetidos CAG del gen de la ataxina-2 en 66 individuos pertenecientes a tres familias mexicanas diagnosticadas clínicamente con ataxia espinocerebelosa tipo 2, y en 400 individuos de una muestra de población mestiza mexicana. Resultados: Se identificó la expansión del repetido CAG en 11 sujetos con sintomatología de ataxia espinocerebelosa tipo 2 y en cuatro individuos asintomáticos, lo que confirmó el diagnóstico en dos de las tres familias analizadas. Se determinó que los pacientes con mayor número de repetidos desarrollaron la sintomatología de la enfermedad a una edad más temprana, fenómeno conocido como “anticipación”. Los alelos silvestres presentaron un rango entre 13 y 30 repetidos CAG, siendo el alelo de 22 repetidos el más frecuente, mientras que los alelos mutados mostraron un rango de 36 a 54 repetidos. Conclusiones: La identificación de la expansión del repetido CAG del gen de la ataxina-2 confirmó el diagnóstico clínico de ataxia espinocerebelosa tipo 2.

BACKGROUND: Spinocerebellar ataxia type 2 (SCA2) results from the expansion of a CAG triplet located within the coding sequence of the ataxin-2 gene, which ultimately provokes the incorporation of a stretch of polyglutamines in the mutant protein. METHODS: We determined by PCR and capillary electrophoresis the number of ataxin2 gene CAG repeats in 66 individuals belonging to 3 families, clinically diagnosed with SCA2, and 400 subjects from a sample of the mestizo Mexican population. RESULTS: The CAG repeat expansion was found in 11 symptomatic subjects and four asymptomatic individuals, confirming the SCA2 clinical diagnosis in two out of the three families studied. We noted that patients with longer CAG repeat numbers have an early disease onset, a phenomenon known as anticipation. Wild-type alleles showed a CAG repeat range between 13 and 30, and the allele carrying 22 CAG repeats was the most common among our sample. Mutant alleles also displayed a range between 36 and 54 CAG repeats. CONCLUSIONS: The identification of the CAG repeat expansion facilitates an accurate SCA2 diagnosis.

Trinucleotide Repeats Number in SCA2, SCA3, and SCA17 in Early-Onset Parkinson's Disease

BACKGROUND: Abnormal expansion of trinucleotide repeats in genes causing spinocerebellar ataxias such as SCA2, SCA3, SCA8, or SCA17 was reported in sporadic or familial Parkinson's disease. Genetic factors play an important role especially in early-onset Parkinson's disease (EOPD). To investigate mutations of ATXN2, ATXN3, and TBP as a possible cause in Korean EOPD, we analyzed mutations in these genes. We also investgated the possibility that trinucleotide repeats numbers in these genes contribute to the development of EOPD. METHODS: Mutation analysis of ATXN2, ATXN3, and TBP was done in 153 EOPD defined as age-at-onset before 51. Distribution of CAG repeats numbers were compared between EOPD and age- and sex-matched controls. RESULTS: No patients with EOPD had CAG repeats numbers in ATXN2, ATXN3, and TBP in mutation range. There was no difference in the distribution of CAG repeats between EOPD and controls, although we found a trend that CAG repeats numbers in ATXN3 appear larger in EOPD than in controls. CONCLUSIONS: Mutations of genes causing SCA2, SCA3, or SCA17 may not be a common genetic cause in Korean EOPD.

Clinical characteristics of congenital myotonic dystrophy diagnosed by molecular genetic method / 소아과

PURPOSE: We performed this study to investigate the perinatal and developmental features of the patients with congenital myotonic dystrophy (CDM) confirmed by the molecular genetic method and the clinical characteristics of their mother, and to identify the relation between the number of CTG repeats and the clinical severity. METHODS: A retrospective review of the medical records and the results of the dystrophia myotonica protein kinase (DMPK) gene test was done for the patients who were confirmed as CDM through gene analysis from January 2001 to September 2006. RESULTS: All of the eight patients (male 2, female 6) showed moderate to severe degree of perinatal distress and feeding difficulty associated with profound hypotonia. Three patients had the history of polyhydramnios and two patients had equinovarus deformity. The developmental milestones were delayed in all patients, which improved gradually with age. All of their mothers demonstrated myotonic symptoms and typical myopathic face. The number of CTG repeats in DMPK gene analysis ranged 1,000-2,083, and there was no significant correlation between the number of CTG repeats and the time of walking alone. CONCLUSION: All patients with CDM presented with severe hypotonia in perinatal period, and developmental delay thereafter, which were improved with age. All of their mothers manifested myotonic symptoms with typical myopathic face, and the identification of such features greatly contributed to the diagnosis of the patients. The number of CTG repeats had no significant influence on the motor development.

X-linked Recessive Bulbospinal Muscular Atrophy (Kennedy's Syndrome): A case report

X-linked recessive bulbospinal muscular atrophy (Kennedy's syndrome) is a variant of the spinal muscular atrophies caused by mutation of androgen receptor gene on X-chromosome. A 69-year-old man had suffered from slowly progressive lower extremity weakness and gynecomastia. Muscle weakness was more severe in proximal muscles and showed symmetrical features. He had fascicular contraction on his face and tongue. All tendon reflexes were absent and pyramidal signs were not detected. Nerve conduction studies were normal except low amplitude of sensory nerve action potential in median nerve. Needle electromyography revealed widespread chronic denervation potentials in all sampling muscles of extremities, facial and tongue muscles. Histopathologic findings showed chronic denervation atrophy. DNA analysis showed abnormal expansion of CAG repeats in the androgen receptor gene and we confirmed this case as Kennedy's syndrome. If an adult patient has slowly progressive muscle weakness, bulbar symptoms and signs of male genital failure, DNA analysis should be taken to differentiate Kennedy syndrome from other motor neuron disease or myopathy.

Human FEN-1 can process the 5'-flap DNA of CTG/CAG triplet repeat derived from human genetic diseases by length and sequence dependent manner

Trinucleotide repeat (TNR) instability can cause a variety of human genetic diseases including myotonic dystrophy and Huntington's disease. Recent genetic data show that instability of the CAG/CTG repeat DNA is dependent on its length and replication origin. In yeast, the RAD27 (human FEN-1 homologue) null mutant has a high expansion frequency at the TNR loci. We demonstrate here that FEN-1 processes the 5'-flap DNA of CTG/CAG repeats, which is dependent on the length in vitro. FEN-1 protein can cleave the 5'-flap DNA containing triplet repeating sequence up to 21 repeats, but the activity decreases with increasing size of flap above 11 repeats. In addition, FEN-1 processing of 5'-flap DNA depends on sequence, which play a role in the replication origin-dependent TNR instability. Interestingly, FEN-1 can cleave the 5'-flap DNA of CTG repeats better than CAG repeats possibly through the flap-structure. Our biochemical data of FEN-1's activity with triplet repeat DNA clearly shows length dependence, and aids our understanding on the mechanism of TNR instability.

Human FEN-1 can process the 5'-flap DNA of CTG/CAG triplet repeat derived from human genetic diseases by length and sequence dependent manner

Trinucleotide repeat (TNR) instability can cause a variety of human genetic diseases including myotonic dystrophy and Huntington's disease. Recent genetic data show that instability of the CAG/CTG repeat DNA is dependent on its length and replication origin. In yeast, the RAD27 (human FEN-1 homologue) null mutant has a high expansion frequency at the TNR loci. We demonstrate here that FEN-1 processes the 5'-flap DNA of CTG/CAG repeats, which is dependent on the length in vitro. FEN-1 protein can cleave the 5'-flap DNA containing triplet repeating sequence up to 21 repeats, but the activity decreases with increasing size of flap above 11 repeats. In addition, FEN-1 processing of 5'-flap DNA depends on sequence, which play a role in the replication origin-dependent TNR instability. Interestingly, FEN-1 can cleave the 5'-flap DNA of CTG repeats better than CAG repeats possibly through the flap-structure. Our biochemical data of FEN-1's activity with triplet repeat DNA clearly shows length dependence, and aids our understanding on the mechanism of TNR instability.

Research on gene mutation and clinical characteristics of hereditary spinocerebellar ataxia type 6 from 2 Chinese families / 中华神经科杂志

Objective To study the gene mutation and clinical characteristics of hereditary spinocerebellar ataxia type 6 (SCA6) from two Chinese families Methods The SCA6 (CAG)n trinucleotide repeat mutations were detected using polymerase chain reaction (PCR) and polyacrylamide gel electrophoresis (PAGE) technique in 210 patients with autosomal dominant SCA from 120 families and 47 sporadic SCA patients,and 50 healthy persons were used as controls. The abnormal allele fragments were sequenced by ABI 377 DNA sequencing machine Results Two SCA families (four patients) had abnormal SCA6 alleles with the CAG repeat expanded to 25 and 26 repeats respectively, as confirmed by DNA sequencing, of which 1.7% (2/120 ) was about the positive rate. Normal SCA6 alleles were carried from 5 to 16 CAG repeats, whereas pathological alleles carry 7 to 17. Analysis of parent child couples demonstrated the existence of marked anticipation with earlier age of onset and a more rapid clinical course in successive generations. The intergenerational stability was noted in the number of CAG repeat. Conclusions Two SCA6 pedigrees have been firstly determined in Chinese from the clinical and genomic aspects. CAG expansions were suggested as the pathogenic cause of SCA6.

Molecular screening for fragile x syndrome in mentally handicapped children in korea

Fragile X syndrome is one of the most common forms of inherited mental retardation and is caused by the expansion of the CGG trinucleotide repeats in the FMR-1 gene. This study was aimed to facilitate the molecular screening of fragile X syndrome in Korean children with mental retardation of unknown etiology. The subjects were tested by Expand Long Template PCR system in the presence of 7-deaza-dGTP, and then by Southern blot analysis. The PCR method provided rapid and reliable results for the identification of fragile X negative and positive patients. One hundred one mentally retarded children (78 males and 23 females) were screened by PCR amplification, which detected only one abnormal sample. The PCR-positive case was confirmed by the CGG repeat expansion on Southern blot analysis with a positive cytogenetic result. In conclusion, Expand Long Template PCR may be used as the first screening test for detecting the fragile X syndrome.

Gene mutation and clinical feature of 10 patients with spinocerebellar ataxia type 2 and type 3 / 中华神经科杂志

Objective To investigate clinical phenotype and the characteristics of gene mutation of patients with spinocercbellar ataxia type 2 and type 3.Methods The trinucleotide repeat mutations were detected by polymerase chain reaction (PCR),fluorescence-PCR and capillary electrophoresis in 9 patients and 43 members from 4 spinocerebellar ataxia families,1 sporadic patients,and 60 normal controls without family history.Results Six patients from 3 families and one sporadic patient had SCA3/MJD (CAG) n expansion mutation(n=68-75) ;Three patients from 1 family had SCA2 allele expansion for 37-41 times. Some of clinical menifestations were same among patients with type 2 or 3,while they showed significant difference in age of onset ,disease devetopment and nervous system injury.Conclusion The difference of clinical feature helps to distinguish SCA3/MJD and SCA2,however genotype analysis is the only method of definite diagnosis.

A Case of Spinocerebellar Ataxia Type 2 / 대한소아신경학회지

This is a case of a boy with autosomal dominant cerebellar ataxia (SCA type 2), which was confirmed by DNA analysis. A 9-year-old boy had been suffering from tremor in both arm and leg for 5 years. After traffic accident, a year ago, the symtoms were more aggravated, and he visted our hospital. The boy showed slow saccades, decreased DTR, ataxic gait and limb ataxia. We analyzed DNA repetition, which revealed positive for the SCA2 expanded repeat.