The impact of ethnicity on the clinical presentations of spinocerebellar ataxia type 3.

BACKGROUND: For a variety of sporadic neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis, it is well-established that ethnicity does affect the disease phenotypes. However, how ethnicity contributes to the clinical symptoms and disease progressions in monogenetic disorders, such as spinocerebellar ataxia type 3 (SCA3), remains less studied. METHODS: We used multivariable linear and logistical regression models in 257 molecularly-confirmed SCA3 patients (66 Caucasians, 43 African Americans, and 148 Asians [composed of 131 Chinese and 17 Asian Americans]) to explore the influence of ethnicity on age at onset (AAO), ataxia severity, and non-ataxia symptoms (i.e. depression, tremor, and dystonia). RESULTS: We found that Asians had significantly later AAO, compared to Caucasians (ß = 4.75, p = 0.000) and to African Americans (ß = 6.64, p = 0.000) after adjusting for the pathological CAG repeat numbers in ATXN3. African Americans exhibited the most severe ataxia as compared to Caucasians (ß = 3.81, p = 0.004) and Asians (ß = 4.39, p = 0.001) after taking into consideration of the pathological CAG repeat numbers in ATXN3 and disease duration. Caucasians had a higher prevalence of depression than African Americans (ß = 1.23, p = 0.040). Ethnicity had no influence on tremor or dystonia. CONCLUSIONS: Ethnicity plays an important role in clinical presentations of SCA3 patients, which could merit further clinical studies and public health consideration. These results highlight the role of ethnicity in monogenetic, neurodegenerative disorders.

Itajaí, Santa Catarina - Azorean ancestry and spinocerebellar ataxia type 3.

The authors present a historical review of spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD), the most common form of spinocerebellar ataxia in Brazil, and consider the high frequency of cases in families from Itajaí, a city on the coast of the state of Santa Catarina with a large population of Portuguese/Azorean descent.

Itajaí, Santa Catarina - Azorean ancestry and spinocerebellar ataxia type 3 / Itajaí, Santa Catarina - descendência açoriana e ataxia espinocerebelar tipo 3

ABSTRACT The authors present a historical review of spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD), the most common form of spinocerebellar ataxia in Brazil, and consider the high frequency of cases in families from Itajaí, a city on the coast of the state of Santa Catarina with a large population of Portuguese/Azorean descent.

RESUMO Os autores apresentam uma revisão histórica sobre a ataxia spinocerebelar tipo 3/doença de Machado-Joseph (SCA3/DMJ), que representa a forma de SCA mais comum em nosso país, considerando a alta frequência de casos oriundos de famílias da cidade de Itajaí, no litoral de Santa Catarina, cidade com ascendência portuguesa-açoriana.

Machado-Joseph disease in a Nigerian family: mutational origin and review of the literature.

Machado-Joseph disease (MJD) has been described in Africans, but no cases have been reported from Nigeria. Current MJD global distribution results from both the ancestral populations-of-origin and the founder effects of mutations, some as a consequence of the Portuguese sea travels in the 15th to 16th century. Two main ancestral haplotypes have been identified: the Machado lineage, which is more recent, predominant in families of Portuguese extraction, and the Joseph lineage, which is much older and worldwide spread, postulated to have an Asian origin. We report a Nigerian family with MJD from Calabar, once settled by Portuguese slave traders, and assessed its mutational origin. The proband was a 33-year-old man with progressive unsteady gait, weakness of all limbs, dysphagia, dysarthria, urinary frequency and diaphoresis. He had end-of-gaze nystagmus, spastic quadriparesis and atrophic small muscles of the hand. He showed fibrillation potentials on EMG, and nerve conduction studies suggested a central axonopathy without demyelination. This family bears the Joseph haplotype, which has a founder effect in the island of Flores, in the Azores (and their descendants in North-America), but is also the most common in non-Portuguese populations worldwide, with an estimated mutation age of around 7000 years.

Mutational origin of Machado-Joseph disease in the Australian Aboriginal communities of Groote Eylandt and Yirrkala.

OBJECTIVE: To determine whether the presence of Machado-Joseph disease (MJD, also spinocerebellar ataxia type 3 [SCA3]) among Australian aborigines was caused by a new mutational event or by the introduction of expanded alleles from other populations. DESIGN: We sequenced a region of 4 kilobases (kb), encompassing the CAG repeat within the ATXN3 gene, in 2 affected Australian aboriginal families and compared them with the Joseph and Machado lineages described before. Full-extended haplotypes (including also more distant single-nucleotide polymorphisms and flanking short tandem repeats) were assessed by segregation and allele-specific amplification. A phylogenetic tree was inferred from genetic distances, and age of the Australasian Joseph-derived lineage was estimated. SETTING: The aboriginal communities of Groote Eylandt and Yirrkala, in the Northern Territories, Australia (local ethics institutional permission was granted, and both community and individual informed consent was obtained). SUBJECTS: A convenience sample of 19 patients and unaffected relatives, from 2 Australian aboriginal families affected with MJD; 40 families with MJD of multiethnic origins and 50 unrelated Asian control subjects. RESULTS: The 2 aboriginal families shared the same full haplotype, including 20 single-nucleotide polymorphisms:TTGATCGAGC-(CAG)(Exp)-CACCCAGCGC, that is, the Joseph lineage with a G variant in rs56268847.Among 33 families with the Joseph lineage, this derived haplotype was found only in 5 of 16 Taiwanese, all 3 Indian,and 1 of 3 Japanese families analyzed. CONCLUSION: A related-extended MJD haplotype shared by Australian aborigines and some Asian families (a Joseph-derived lineage) suggests a common ancestor for all, dating back more than 7000 years.

Analysis of mitochondrial DNA variations in a Chinese family with spinocerebellar ataxia.

Mitochondrial dysfunction and mitochondrial DNA (mtDNA) variations have been shown to have a role in several neurological diseases. To determine whether there is an association between mtDNA variations and spinocerebellar ataxia (SCA), we analyzed the mtDNA main control region (D-loop), as well as mtDNA content and the prevalence of the common deletion, in blood samples from members of a large Chinese family (14 individuals with SCA and 13 healthy individuals). All 14 individuals with SCA were genotyped as SCA3. Thirteen mtDNA haplotypes were identified among the 27 subjects. We detected no mutations in the mtDNA D-loop region and found no significant differences in mtDNA copy number or common deletion level between patients and their healthy relatives. Contrary to some previous reports, our study showed that mtDNA variations seem to be a rare event in individuals with SCA3.

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.

Founder haplotype for Machado-Joseph disease in the Indian population: novel insights from history and polymorphism studies.

BACKGROUND: The ACA haplotype is associated with 72% of the expanded repeats in Machado-Joseph disease (MJD) worldwide and has been traced to a Portuguese ancestry. It is present in only 5% of the normal chromosomes in the Portuguese population. OBJECTIVE: To trace the origin of expanded alleles of MJD in the Indian population. METHODS: We performed CAG repeat size determination and haplotype analysis for 9 families with MJD and 263 unrelated chromosomes with unexpanded CAG sequences from the Indian population. RESULTS: All the expanded alleles were exclusively associated with the ACA haplotype in the Indian population. Interestingly, this haplotype was very common in normal alleles (40%) as compared with the Portuguese population (5%) and was significantly associated with large normal alleles (Pearson chi(2)1 = 87.1, P<.001) in the Indian population. We also observed a rare intermediate allele of MJD with the ACA haplotype but with a CAG variant instead of CAA at the sixth position in the repeat tract. CONCLUSIONS: Overrepresentation of the ACA haplotype in large normal alleles in India as compared with the Portuguese population suggests that the expansion-prone large normal alleles with the ACA haplotype may have been introduced in the Portuguese population through admixture with South Asian populations. Detailed haplotype analysis of a CAG variant within the repeat tract in an intermediate allele of MJD suggests a mechanism of gene conversion in the expansion.

Genetic polymorphism of MJD1 alleles and molecular analysis of SCA3 patients from Rio de Janeiro, Brazil.

Spinocerebellar ataxia type 3 is the most common form of autosomal dominant cerebellar ataxia. It is a severe progressive neurological disorder caused by an expansion of an exonic CAG repeat of the MJD1 gene. The repeated sequence is polymorphic among both normal individuals and patients. In general, expanded alleles are paternally inherited and the disorder exhibits anticipation. We performed a PCR-based study to determine polymorphisms of the number of CAG repeats of the MJD1 gene in an anonymous sample of normal Brazilian individuals. We also analyzed DNA samples from 9 patients with ataxia. We identified 29 different allele sizes ranging from 12 to 40 CAG repeats, with heterozygosity of 79%. The distribution of allele sizes showed two major peaks of 16 (7%) and 26 (10.1%) CAG repeats. When grouping normal alleles by size, we observed that the distribution varies between males and females, and a significant deviation from the Hardy-Weinberg equilibrium was observed with an excess of normal large alleles among males. We also detected expanded alleles with 68-73 CAG repeats in 3 out of 9 ataxic patients.

French Machado-Joseph disease patients do not exhibit gametic segregation distortion: a sperm typing analysis.

Segregation distortion has been reported to occur in a number of the trinucleotide repeat disorders. On the basis of a sperm typing study performed in patients of Japanese descent with Machado-Joseph disease (MJD), it was reported that disease alleles are preferentially transmitted during meiosis. We performed a sperm typing study of five MJD patients of French descent and analysis of the pooled data shows a ratio of mutant to normal alleles of 379:436 (46.5:53.5%), which does not support meiotic segregation distortion. To confirm these results, sperm typing analysis was also performed using a polymorphic marker, D14S1050, closely linked to the MJD1 gene. Among 910 sperm analyzed, the allele linked to the disease chromosome was detected in 50.3% of the samples and the allele linked to the normal chromosome was found in 49.6% of the sperm. The difference in frequency of these two alleles is not significant ( P = 0.8423). Likelihood-based analysis of segregation distortion in the single sperm data using the SPERMSEG program also showed no support for segregation distortion at the gamete level in this patient population. The previous report on the Japanese patients also suggested that disease allele stability may be influenced by a trans effect of an intragenic polymorphism (987 G/C) in the wild-type allele. All of the French patients were heterozygous for this polymorphism. However, analysis of the variance in repeat number in sperm from the French MJD patients overlapped significantly with the variance in repeat number observed in the C/C homozygous Japanese patients.

Machado-Joseph disease: clinical, molecular, and metabolic characterization in Chinese kindreds.

Machado-Joseph disease, an autosomal dominant multisystem motor degeneration, has been described mainly in people of Portuguese descent. Our report documents the presence of Machado-Joseph disease in the Chinese population, based on the specific molecular marker of a CAG repeat array in the 3' end of the MJD gene. We screened 21 Chinese families with dominant spinocerebellar ataxia. The results showed that Machado-Joseph disease with CAG expansion accounted for 52% of families with autosomal dominant cerebellar ataxia in this series. The clinical characteristics, besides the well-documented cerebellar ataxia, dysarthria, nystagmus, corticospinal dysfunctions, a variable degree of facial muscle fasciculation, and proprioceptive loss, included loss of optokinetic nystagmus and autonomic nervous system dysfunction. The CAG repeat number in the MJD gene ranged from 14 to 39 among normal alleles, and from 63 to 81 among MJD alleles. There was a strong inverse correlation (gamma = -0.77) between number of CAG repeats and age at symptom onset, accounting for 60% of the variance of age at onset. A strong clinical anticipation of age at onset existed in successive generations. Mild instabilities of expanded CAG repeat numbers during meiotic transmission occurred, with no significant difference according to the gender of the transmitting parent. Finally, brain metabolism in Machado-Joseph disease, studied with positron emission tomography, was characterized by significant progressive regional hypometabolism in the occipital cortex, as well as the cerebellar hemispheres, vermis, and brainstem.

Autosomal dominant cerebellar ataxias in the Kinki area of Japan.

The autosomal dominant cerebellar ataxias are a heterogeneous group of neurodegenerative disorders characterized by slowly progressive cerebellar ataxia. Recently, among the ataxias, spinocerebellar ataxia type 1 (SCA1), Machado-Joseph disease (MJD) and dentatorubral-pallidoluysian atrophy have been found to be caused by expansion of a CAG trinucleotide repeat in the coding region of the disease genes. We have analyzed the CAG repeats of 67 patients from 47 families with dominantly inherited ataxia who lived in the Kinki area of Japan. The following results were obtained. First, 31 patients from 22 families were found to be positive for the MJD repeat expansion, indicating that MJD is the most common dominantly inherited ataxia in the Kinki area of Japan. Second, no SCA1 repeat expansion was found among the families studied. This presents a striking contrast to the fact that there are many families with SCA1 in Hokkaido and the Tohoku area of Japan. These findings suggest geographic variation in autosomal dominant cerebellar ataxias in Japan.

Linkage disequilibrium analysis in Machado-Joseph disease patients of different ethnic origins.

Machado-Joseph disease (MJD) is an autosomal dominant spinocerebellar degeneration originally described in families of Portuguese-Azorean ancestry. The hypothesis that its present world distribution could result from the spread of an original founder mutation has been raised. To test this possibility we have conducted a linkage disequilibrium study of markers segregating with the MJD1 locus in a total of 64 unrelated families of different geographical origins. Significant association was detected between the MJD1 locus and marker alleles at loci D14S280, D14S1050 and D14S81. All affected individuals, except one Chinese family, had allele 3 (237 bp) at D14S280. This finding is consistent with a founder effect in our MJD population. However, distinct haplotypes were observed in patients originating from the two Azorean islands showing the highest disease prevalence; therefore, the possible existence of more than one founder mutation can not be excluded with the markers currently available.

Relations between genotype and phenotype in German patients with the Machado-Joseph disease mutation.

OBJECTIVE: Machado-Joseph disease (MJD) is an autosomal dominant cerebellar ataxia with extensive phenotypic variability originally described in families of Portuguese ancestry. Recently, the mutation causing the disease has been identified as an expanded CAG trinucleotide repeat. In this study relations between genotype and phenotype were investigated. METHODS: A series of 180 German patients with degenerative forms of ataxia were clinically and genetically examined. Patients bearing the MJD mutation were assigned to three phenotypes: phenotype 1 characterised by early onset and dystonia or pronounced rigidity associated with ataxia and spasticity. Main symptoms in phenotype 2 were ataxia and spasticity. In phenotype 3 onset was relatively late and peripheral neuropathy accompanied ataxia. Clinical and molecular data were correlated. RESULTS: An expanded CAG array was found in 42 patients from 22 families. Repeat length of CAG varied between 67 and 80 CAG motifs and showed an inverse correlation with the age of onset. For the development of phenotype 1 early onset (< 20 years) seemed more decisive than extensive repeat length. Phenotype 2 was present in all patients with more than 73 CAG motifs and onset between 20 and 40. Phenotype 3 developed in most patients with less than 73 CAG motifs and onset was regularly beyond the age of 40. Intrafamilial variability of both repeat length and phenotype was large reflecting meiotic instability of the expanded CAG repeat. CONCLUSIONS: The MJD mutation is the most frequent cause of dominantly inherited ataxia in Germany. Variations in repeat lengths substantially influence age of onset as well as phenotype but cannot explain why MJD characteristics of Portuguese families such as "bulging eyes", dystonia, and rigidity are essentially missing in German families. Despite the genotypic and phenotypic relations found in this study a reliable individual prognosis of the course of the disease is not possible at a presymptomatic stage.

Intergenerational instability of the CAG repeat of the gene for Machado-Joseph disease (MJD1) is affected by the genotype of the normal chromosome: implications for the molecular mechanisms of the instability of the CAG repeat.

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder caused by unstable expansion of a CAG repeat in the MJD1 gene at 14q32.1. To identify elements affecting the intergenerational instability of the CAG repeat, we investigated whether the CGG/GGG polymorphism at the 3' end of the CAG repeat affects intergenerational instability of the CAG repeat. The [expanded (CAG)n-CGG]/[normal (CAG)n-GGG] haplotypes were found to result in significantly greater instability of the CAG repeat compared to the [expanded (CAG)n-CGG]/[normal (CAG)n-CGG] or [expanded (CAG)nGGG]/[normal (CAG)n-GGG] haplotypes. Multiple stepwise logistic regression analysis revealed that the relative risk for a large intergenerational change in the number of CAG repeat units (< -2 or > 2) is 7.7-fold (95% CI: 2.5-23.9) higher in the case of paternal transmission than in that of maternal transmission and 7.4-fold (95% CI: 2.4-23.3) higher in the case of transmission from a parent with the [expanded (CAG)n-CGG]/[normal (CAG)n-GGG] haplotypes than in that of transmission from a parent with the [expanded (CAG)n-CGG]/[normal (CAG)n-CGG] or [expanded (CAG)n-GGG]/[normal (CAG)n-GGG] haplotypes. The combination of paternal transmission and the [expanded (CAG)n-CGG]/[normal (CAG)n-GGG] haplotypes resulted in a 75.2-fold (95% CI: 9.0-625.0) increase in the relative risk compared with that of maternal transmission and the [expanded (CAG)n-CGG]/[normal (CAG)n-CGG] or [expanded (CAG)n-GGG]/[normal (CAG)n-GGG] haplotypes. The results suggest that an inter-allelic interaction is involved in the intergenerational instability of the expanded CAG repeat.

Machado-Joseph (Azorean) disease in a Yemenite Jewish family in Israel.

Machado-Joseph disease (MJD), an autosomal dominant, progressive, multisystem degeneration with cerebellar ataxia as the cardinal manifestation, usually affects individuals of Portuguese ancestry from the Azorean Islands. Cases have been reported in families from Japan, India, China, Brazil, and Australia. We report the first Israeli Jewish family with MJD, originating from a remote village near Ta'izz in Yemen.

A dominant hereditary ataxia resembling Machado-Joseph disease in Arnhem Land, Australia.

A dominant ataxia among four families of the Arnhem Land Aboriginal people of Northern Australia has many clinical features in common with Machado-Joseph disease. Neuropathology on one case showed multiple system involvement, with sparing of the inferior olives and cerebellar cortex, consistent with Machado-Joseph disease. Portuguese ancestry is possible, although not proven.