Spinocerebellar ataxia type 2 has multiple ancestral origins

INTRODUCTION

Spinocerebellar ataxia type 2 (SCA2) is a dominant neurodegenerative disorder due to expansions of a CAG repeat tract (CAGexp) at the ATXN2 gene. Previous studies found only one ancestral haplotype worldwide, with a C allele at rs695871. This homogeneity was unexpected, given the severe anticipations related to SCA2. We aimed to describe informative ancestral haplotypes found in South American SCA2 families.

METHODS

Seventy-seven SCA2 index cases were recruited from Brazil, Peru, and Uruguay; 263 normal chromosomes were used as controls. The SNPs rs9300319, rs3809274, rs695871, rs1236900 and rs593226, and the STRs D12S1329, D12S1333, D12S1672 and D12S1332, were used to reconstruct haplotypes.

RESULTS

Eleven ancestral haplotypes were found in SCA2 families. The most frequent ones were A-G-C-C-C (46.7 % of families), G-C-C-C-C (24.6 %) and A-C-C-C-C (10.3 %) and their mean (sd) CAGexp were 41.68 (3.55), 40.42 (4.11) and 45.67 (9.70) (p = 0.055), respectively. In contrast, the mean (sd) CAG lengths at normal alleles grouped per haplotypes G-C-G-A-T, A-G-C-C-C and G-C-C-C-C were 22.97 (3.93), 23.85 (3.59), and 30.81 (4.27) (p < 0.001), respectively. The other SCA2 haplotypes were rare: among them, a G-C-G-A-T lineage was found, evidencing a G allele in rs695871.

CONCLUSION

We identified several distinct ancestral haplotypes in SCA2 families, including an unexpected lineage with a G allele at rs695871, a variation never found in hundreds of SCA2 patients studied worldwide. SCA2 has multiple origins in South America, and more studies should be done in other regions of the world.

A model for the dynamics of expanded CAG repeat alleles: ATXN2 and ATXN3 as prototypes

Background: Spinocerebellar ataxia types 2 (SCA2) and 3 (SCA3/MJD) are diseases due to dominant unstable expansions of CAG repeats (CAGexp). Age of onset of symptoms (AO) correlates with the CAGexp length. Repeat instability leads to increases in the expanded repeats, to important AO anticipations and to the eventual extinction of lineages. Because of that, compensatory forces are expected to act on the maintenance of expanded alleles, but they are poorly understood. Objectives: we described the CAGexp dynamics, adapting a classical equation and aiming to estimate for how many generations will the descendants of a de novo expansion last. Methods: A mathematical model was adapted to encompass anticipation, fitness, and allelic segregation; and empirical data fed the model. The arbitrated ancestral mutations included in the model had the lowest CAGexp and the highest AO described in the literature. One thousand generations were simulated until the alleles were eliminated, fixed, or 650 generations had passed. Results: All SCA2 lineages were eliminated in a median of 10 generations. In SCA3/MJD lineages, 593 were eliminated in a median of 29 generations. The other ones were eliminated due to anticipation after the 650th generation or remained indefinitely with CAG repeats transitioning between expanded and unexpanded ranges. Discussion: the model predicted outcomes compatible with empirical data - the very old ancestral SCA3/MJD haplotype, and the de novo SCA2 expansions -, which previously seemed to be contradictory. This model accommodates these data into understandable dynamics and might be useful for other CAGexp disorders.

An Exploratory Survey on the Care for Ataxic Patients in the American Continents and the Caribbean

Little is known about access of rare disease carriers to health care. To increase this knowledge, the Pan American Hereditary Ataxia Network (PAHAN) conducted an exploratory survey about care for hereditary ataxias in American continents and the Caribbean. A questionnaire was sent to health professionals about the hereditary ataxias identified; access to care; and local teaching and research. The number of ataxics under current care per 100,000 inhabitants was subtracted from the expected overall prevalence of 6/100,000, to estimate the prevalence of uncovered ataxic patients. Local Human Development Indexes (HDI) were used to measure socio-economic factors. Twenty-six sites participated. Twelve sites had very high, 13 had high, and one site had medium HDI. Participants reported on 2239 and 602 patients with spinocerebellar ataxias and recessive forms under current care. The number of patients under current care per inhabitants varied between 0.14 and 12/100,000. The estimated prevalence of uncovered ataxic patients was inversely proportional to HDIs (rho = 0.665, p = 0.003). Access to diagnosis, pre-symptomatic tests, and rehabilitation were associated with HDIs. More and better molecular diagnostic tools, protocols and guidelines, and professional training for ataxia care were the top priorities common to all respondents. Evidence of inequalities was confirmed. Lower HDIs were associated with high potential numbers of uncovered ataxic subjects, and with lack of molecular diagnosis, pre-symptomatic testing, and rehabilitation. More and better diagnostic tools, guidelines, and professional training were priorities to all sites. PAHAN consortium might help with the last two tasks.

Diagnostic Delay of Hereditary Ataxias in Brazil: the Case of Machado-Joseph Disease

BACKGROUND

Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is a rare disease with diagnosis offered by the Unified Health System in Brazil. Our aim was to investigate the diagnostic delay in an interval of 23 years in a public university hospital, and some potentially determining factors.

METHODS

A retrospective review of the medical records of subjects identified at our institution between 1999 and 2017 was carried out, including residents of Rio Grande do Sul. The diagnostic delay was equivalent to the difference between age at onset of symptoms and age at molecular diagnosis. Calendar years, educational level, sex, distance between the household and the clinics, age and being the index case were studied as modifying factors.

RESULTS

SCA3/MJD had a median diagnostic delay of 5 years. Index cases had delays of 6 versus 4 years (p<0.001) for subsequent family members. Delay correlated with age (rho=0.346, p<0.001), but not with age at disease onset (rho=0.005, p=0.91). No change was observed with the level of education of individuals or with the distance between household and hospital from 1999 to 2017.

DISCUSSION

The diagnostic delay of SCA3/MJD is high in our region, where its occurrence has been reported for years. Failure to change the delay over the years suggests ineffective dissemination to the population, but a smaller lag among younger people can portray the effect of digital inclusion.

FOXO1 controls protein synthesis and transcript abundance of mutant polyglutamine proteins, preventing protein aggregation

FOXO1, a transcription factor downstream of the insulin/insulin like growth factor axis, has been linked to protein degradation. Elevated expression of FOXO orthologs can also prevent the aggregation of cytosine adenine guanine (CAG)-repeat disease causing polyglutamine (polyQ) proteins but whether FOXO1 targets mutant proteins for degradation is unclear. Here, we show that increased expression of FOXO1 prevents toxic polyQ aggregation in human cells while reducing FOXO1 levels has the opposite effect and accelerates it. Although FOXO1 indeed stimulates autophagy, its effect on polyQ aggregation is independent of autophagy, ubiquitin-proteasome system (UPS) mediated protein degradation and is not due to a change in mutant polyQ protein turnover. Instead, FOXO1 specifically downregulates protein synthesis rates from expanded pathogenic CAG repeat transcripts. FOXO1 orchestrates a change in the composition of proteins that occupy mutant expanded CAG transcripts, including the recruitment of IGF2BP3. This mRNA binding protein enables a FOXO1 driven decrease in pathogenic expanded CAG transcript- and protein levels, thereby reducing the initiation of amyloidogenesis. Our data thus demonstrate that FOXO1 not only preserves protein homeostasis at multiple levels, but also reduces the accumulation of aberrant RNA species that may co-contribute to the toxicity in CAG-repeat diseases.

Free carnitine and branched chain amino acids are not good biomarkers in Huntington's disease

BACKGROUND

Huntington's disease (HD), caused by an expanded CAG repeat at HTT, has no treatment, and biomarkers are needed for future clinical trials.

OBJECTIVE

The objective of this study was to verify if free carnitine and branched chain amino acids levels behave as potential biomarkers in HD.

METHODS

Symptomatic and asymptomatic HD carriers and controls were recruited. Age, sex, body mass index (BMI), age of onset, disease duration, UHDRS scores, and expanded CAG tract were obtained; valine, leucine, isoleucine, and free carnitine were measured. Baseline and longitudinal analysis were performed.

RESULTS

Seventy-four symptomatic carriers, 20 asymptomatic carriers, and 22 non-carriers were included. At baseline, valine levels were reduced in symptomatic and asymptomatic HD carriers when compared to non-carriers. No difference in free carnitine or isoleucine+leucine levels were observed between groups. BMI of symptomatic individuals was lower than those of non-carriers. Valine levels correlated with BMI. Follow-up evaluation was performed in 43 symptomatic individuals. UHDRS total motor score increased 4.8 points/year on average. No significant reductions in BMI or valine were observed, whereas free carnitine and isoleucine+leucine levels increased.

CONCLUSIONS

Although valine levels were lower in HD carriers and were related to BMI losses observed in pre-symptomatic individuals, none of these metabolites seem to be biomarkers for HD.

Correction to: Genetic Analysis of Hereditary Ataxias in Peru Identifies SCA10 Families with Incomplete Penetrance

The original version of this article unfortunately contained some mistakes in Table 2. The additional row (just above SCA2) with the following information "SCA1, 1(1), 1, 50, 74, 24, 46 and 0/1" should be inserted.

Genetic Analysis of Hereditary Ataxias in Peru Identifies SCA10 Families with Incomplete Penetrance

Relative frequency of hereditary ataxias remains unknown in many regions of Latin America. We described the relative frequency in spinocerebellar ataxias (SCA) due to (CAG)n and to (ATTCT)n expansions, as well as Friedreich ataxia (FRDA), among cases series of ataxic individuals from Peru. Among ataxic index cases from 104 families (38 of them with and 66 without autosomal dominant pattern of inheritance), we identified 22 SCA10, 8 SCA2, 3 SCA6, 2 SCA3, 2 SCA7, 1 SCA1, and 9 FRDA cases (or families). SCA10 was by far the most frequent one. Findings in SCA10 and FRDA families were of note. Affected genitors were not detected in 7 out of 22 SCA10 nuclear families; then overall maximal penetrance of SCA10 was estimated as 85%; in multiplex families, penetrance was 94%. Two out of nine FRDA cases carried only one allele with a GAA expansion. SCA10 was the most frequent hereditary ataxia in Peru. Our data suggested that ATTCT expansions at ATXN10 might not be fully penetrant and/or instability between generations might frequently cross the limits between non-penetrant and penetrant lengths. A unique distribution of inherited ataxias in Peru requires specific screening panels, considering SCA10 as first line of local diagnosis guidelines.

Minimal prevalence of Huntington's disease in the South of Brazil and instability of the expanded CAG tract during intergenerational transmissions

Huntington’s disease (HD) is due to dominant expansions of the CAG repeat of the HTT gene. Meiotic instability of the (CAG)_n might impact the disorder frequency. We report on HD minimal prevalence in Rio Grande do Sul (RS) state, Brazil, and on intergenerational instability of the (CAG)_n in HD families. Symptomatic and at-risk subjects from 179 HD families were ascertained between 2013 and 2016. Clinical, molecular and family history data were obtained. Expanded (CAG)_n length differences between parent and child (delta-expanded-(CAG)_n) were calculated. Effect of parental age on the (CAG)_n instability upon transmission was inferred by correlating delta-expanded-(CAG)_n between siblings to their age differences. HD minimal prevalence in RS state was estimated as 1.85:100,000 inhabitants. Alleles with (CAG)_27-35 were found on 21/384 non-disease associated chromosomes (5.5%); among 253 expanded alleles, four (1.6%) were within reduced penetrance range with (CAG)_36-39. In 32 direct transmissions, mean instability was larger among paternal than maternal transmissions. In direct transmissions and in 51 sibling pairs, parental age at the time of child birth were not correlated with delta-expanded-(CAG)_n. Briefly, HD prevalence in RS state was lower than those reported for European populations. Expanded (CAG)_n transmissions were unstable and not associated to parental age.

State biomarkers for Machado Joseph disease: Validation, feasibility and responsiveness to change

Machado-Joseph disease (SCA3/MJD) is the most common spinocerebellar ataxia worldwide, and particularly so in Southern Brazil. Due to an expanded polyglutamine at ataxin-3, SCA3/MJD presents a relentless course with no current disease modifying treatment. Clinical scales used to measure SCA3/MJD progression present moderate effect sizes, a major drawback for their use as main outcomes in clinical trials, given the rarity and slow progression of the disease. This limitation might be overcome by finding good surrogate markers. We present here a review of studies on peripheral and neurophysiological markers in SCA3/MJD that can be candidates for state biomarkers. Data on markers already studied were summarized, giving emphasis on validation against clinical scale, and responsiveness to change. While some biological fluid compounds and neurophysiological parameters showed poor responsiveness, others seemed to be good candidates. Some potential candidates that are waiting for responsiveness studies were serum levels of neuron specific enolase, vestibulo-ocular reflex and video-oculography. Candidates evaluated by RNA and microRNA expression levels need further studies to improve their measurements. Data on peripheral levels of Beclin-1 and DNAJB1 are promising but still incipient. We conclude that several potential candidates should follow onto validating studies for surrogate state biomarkers of SCA3/MJD.

Correction to: Selective Forces Related to Spinocerebellar Ataxia Type 2

The original version of this article unfortunately contained a mistake. The spelling of the surname of one co-author from the publication entitled "Selective Forces Related to Spinocerebellar Ataxia Type 2" that was recently published in the journal "The Cerebelum" was incorrect.

The progression rate of spinocerebellar ataxia type 2 changes with stage of disease

Background

Spinocerebellar ataxia type 2 (SCA2) affects several neurological structures, giving rise to multiple symptoms. However, only the natural history of ataxia is well known, as measured during the study duration. We aimed to describe the progression rate of ataxia, by the Scale for the Assessment and Rating of Ataxia (SARA), as well as the progression rate of the overall neurological picture, by the Neurological Examination Score for Spinocerebellar Ataxias (NESSCA), and not only during the study duration but also in a disease duration model. Comparisons between these models might allow us to explore whether progression is linear during the disease duration in SCA2; and to look for potential modifiers.

Results

Eighty–eight evaluations were prospectively done on 49 symptomatic subjects; on average (SD), study duration and disease duration models covered 13 (2.16) months and 14 (6.66) years of individuals’ life, respectively. SARA progressed 1.75 (CI 95%: 0.92–2.57) versus 0.79 (95% CI 0.45 to 1.14) points/year in the study duration and disease duration models. NESSCA progressed 1.45 (CI 95%: 0.74–2.16) versus 0.41 (95% CI 0.24 to 0.59) points/year in the same models. In order to explain these discrepancies, the progression rates of the study duration model were plotted against disease duration. Then an acceleration was detected after 10 years of disease duration: SARA scores progressed 0.35 before and 2.45 points/year after this deadline (p = 0.013). Age at onset, mutation severity, and presence of amyotrophy, parkinsonism, dystonic manifestations and cognitive decline at baseline did not influence the rate of disease progression.

Conclusions

NESSCA and SARA progression rates were not constant during disease duration in SCA2: early phases of disease were associated with slower progressions. Modelling of future clinical trials on SCA2 should take this phenomenon into account, since disease duration might impact on inclusion criteria, sample size, and study duration. Our database is available online and accessible to future studies aimed to compare the present data with other cohorts.

Electronic supplementary material

The online version of this article (10.1186/s13023-017-0725-y) contains supplementary material, which is available to authorized users.

Peripheral Oxidative Stress Biomarkers in Spinocerebellar Ataxia Type 3/Machado-Joseph Disease

OBJECTIVES

Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is a polyglutamine disorder with no current disease-modifying treatment. Conformational changes in mutant ataxin-3 trigger different pathogenic cascades, including reactive oxygen species (ROS) generation; however, the clinical relevance of oxidative stress elements as peripheral biomarkers of SCA3/MJD remains unknown. We aimed to evaluate ROS production and antioxidant defense capacity in symptomatic and presymptomatic SCA3/MJD individuals and correlate these markers with clinical and molecular data with the goal of assessing their properties as disease biomarkers.

METHODS

Molecularly confirmed SCA3/MJD carriers and controls were included in an exploratory case-control study. Serum ROS, measured by 2',7'-dichlorofluorescein diacetate (DCFH-DA) as well as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) antioxidant enzyme activities, levels were assessed.

RESULTS

Fifty-eight early/moderate stage symptomatic SCA3/MJD, 12 presymptomatic SCA3/MJD, and 47 control individuals were assessed. The DCFH-DA levels in the symptomatic group were 152.82 nmol/mg of protein [95% confidence interval (CI), 82.57-223.08, p < 0.001] higher than in the control and 243.80 nmol/mg of protein (95% CI, 130.64-356.96, p < 0.001) higher than in the presymptomatic group. The SOD activity in the symptomatic group was 3 U/mg of protein (95% CI, 0.015-6.00, p = 0.048) lower than in the presymptomatic group. The GSH-Px activity in the symptomatic group was 13.96 U/mg of protein (95% CI, 5.90-22.03, p < 0.001) lower than in the control group and 20.52 U/mg of protein (95% CI, 6.79-34.24, p < 0.001) lower than in the presymptomatic group and was inversely correlated with the neurological examination score for spinocerebellar ataxias (R = -0.309, p = 0.049).

CONCLUSION

Early/moderate stage SCA3/MJD patients presented a decreased antioxidant capacity and increased ROS generation. GSH-Px activity was the most promising oxidative stress disease biomarker in SCA3/MJD. Further longitudinal studies are necessary to identify both the roles of redox parameters in SCA3/MJD pathophysiology and as surrogate outcomes for clinical trials.

Cytokines in Machado Joseph Disease/Spinocerebellar Ataxia 3

The aim of the present study is to describe the serum concentrations of a broad spectrum of cytokines in symptomatic and asymptomatic carriers of Machado Joseph disease (SCA3/MJD) CAG expansions. Molecularly confirmed carriers and controls were studied. Age at onset, disease duration, and clinical scales Scale for the Assessment and Rating of Ataxia (SARA), Neurological Examination Score for Spinocerebellar Ataxias (NESSCA), SCA Functional Index (SCAFI), and Composite Cerebellar Functional Score (CCFS) were obtained from the symptomatic carriers. Serum was obtained from all individuals and a cytokine panel "consisted of" eotaxin, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon (IFN)-α, IFN-γ, interleukin (IL)-1β, IL-1RA, IL-2, IL-2R, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-15, IL-17, interferon gamma-induced protein (IP)-10, monocyte chemoattractant protein (MCP)-1, monokine induced by gamma interferon (MIG), macrophage inflammatory protein (MIP)-a, MIP-b, regulated on activation, normal T cell expressed and secreted (RANTES) and tumor necrosis factor (TNF)-α was analyzed. In a subgroup of symptomatic carriers, the cytokine panel was repeated after 360 days. Cytokine distribution among groups was studied by discriminant analysis; changes in serum levels after 360 days were studied by generalized estimation equation. Sixty-six symptomatic carriers, 13 asymptomatic carriers, and 43 controls were studied. No differences in cytokine patterns were found between controls and carriers of the CAG expansions or between controls and symptomatic carriers only. In contrast, eotaxin concentrations were significantly higher in asymptomatic than in symptomatic carriers or in controls (p = 0.001, ANCOVA). Eotaxin did not correlate with age, disease duration, CAG expansion, NESSCA score, and SARA score. Among symptomatic carriers, eotaxin dropped after 360 days (p = 0.039, GEE). SCA3/MJD patients presented a benign pattern of serum cytokines. In contrast, levels of eotaxin, a peptide secreted by astrocytes, were elevated in the asymptomatic carriers, suggesting that a specific response of these cells can be related to symptom progression, in SCA3/MJD.

Spinocerebellar ataxia type 3/Machado-Joseph disease: segregation patterns and factors influencing instability of expanded CAG transmissions

Controversies about Mendelian segregation and CAG expansion (CAGexp) instabilities during meiosis in spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) need clarification. Additional evidence about these issues was obtained from the cohort of all SCA3/MJD individuals living in South Brazil. A survey was carried out to update information registered since 2001. Deaths were checked with the Public Information System, and data was made anonymous. Anticipation and delta-CAGexp from parent-offspring pairs, and delta-CAGexp between siblings were obtained. One hundred and fifty-nine families (94% of the entire registry) were retrieved, comprising 3725 living individuals as of 2015, 625 of these being symptomatic. Minimal prevalence was 6:100,000. Carriers of a CAGexp represented 65.6% of sibs in the genotyped offspring (p < 0.001). Median instability was larger among paternal than maternal transmissions, and instabilities correlated with anticipation (r = 0.38; p = 0.001). Age of the parent correlated to delta-CAGexp among 115 direct parent-offspring CAGexp transmissions (ρ = 0.23, p = 0.014). In 98 additional kindreds, the delta-CAGexp between 269 siblings correlated with their delta-of-age (ρ = 0.27, p < 0.0001). SCA3/MJD was associated with a segregation distortion favoring the expanded allele in our cohort. Instability of expansion during meiosis was weakly influenced by the age of the transmitting parent at the time of conception.

Spinocerebellar ataxia type 3/Machado-Joseph disease starting before adolescence

Onset of Machado-Joseph disease (SCA3/MJD) before adolescence has been rarely reported. This study aims to describe a cohort of SCA3/MJD with onset before 12 years of age, comparing their disease progression with the progression observed in patients with usual disease onset. We identified all cases from our cohort whose onset was before adolescence. After consent, patients were examined with clinical scales Scale for the Assessment and Rating of Ataxia (SARA) and Neurological Examination Score for Spinocerebellar Ataxia (NESSCA). Gender, age, age at onset, disease duration, CAG expanded repeats, transmitting parent, and anticipation of cases with infantile and adult onset were studied. Progression of NESSCA and SARA scores was estimated through a mixed model, and was compared with a historical group with onset after adolescence. Between 2000 and 2014, 461 symptomatic individuals from our region were diagnosed as SCA3/MJD. Onset of eight cases (2.2%), all heterozygotes, was before adolescence: seven were females (p = 0.054). CAG expanded repeats--75 ± 3 versus 84 ± 4--and anticipations--7 ± 9.7 versus 14.4 ± 7.2 years--were different between early childhood and adult onset groups (p < 0.03). The median survival of early childhood onset group was 23 years of age. The annual progression of SARA--2.3 and 0.6 points/year (p = 0.001)--and NESSCA--2.04 and 0.88 points/year (p = 0.043)--was faster in childhood than in adult onset group. Onset of SCA3/MJD before adolescence was related to larger expanded CAG repeats in heterozygosis; females seemed to be at higher risk. Disease progression was faster than in SCA3/MJD starting after 12 years.

Planning future clinical trials in Machado Joseph disease: Lessons from a phase 2 trial

BACKGROUND

In a recent phase 2 clinical trial in spinocerebellar ataxia type 3/Machado Joseph disease (SCA3/MJD), a neurogenetic disorder without specific therapy, benefits of lithium carbonate were found only on secondary efficacy outcomes, all related to ataxic features. In order to help designing future studies, we further analyzed the trial data searching for treatment response modifiers and metric properties of spinocerebellar ataxia (SCA) scales.

METHODS

Efficacy analysis was performed with the Neurological Examination Score for the Assessment of Spinocerebellar Ataxia (NESSCA) and the Scale for the Assessment and Rating of Ataxia (SARA) subscores and with the subgroup of patients with independent gait according to the 8-meter walking-time (8MW). Interactions of clinical/molecular findings with treatment response, minimally important differences (MIDs), and sample size estimations for NESSCA, SARA, Spinocerebellar Ataxia Functional Index (SCAFI) and Composite Cerebellar Functional Score (CCFS) were evaluated.

RESULTS

62 SCA3/MJD patients had been randomly assigned (1:1) for the double-blind, placebo-controlled trial. While cerebellar NESSCA (range: 0-7 points) differed between groups 0.64 points (95% CI 0.23 to 1.05, p<0.001) over the whole 48weeks of study, favoring lithium, no effect was found on non-ataxia subscores. Among patients able to perform the 8MW on baseline, NESSCA (p=0.010) and SCAFI (p=0.015) differed between groups favoring lithium. Finally, estimated sample sizes for the scales were provided.

CONCLUSION

Lithium efficacy on cerebellar NESSCA, and on SCAFI and CCFS in the primary analysis, together with the lack of effect on non-ataxia features suggests that lithium should be tested in phase 3 trials in SCA3/MJD and that ataxia scales should be preferred to multisystem neurological instruments as the primary outcome. The inclusion of early stage patients is advisable in future clinical trials in SCA3/MJD.

TRIAL REGISTRATION

clinicaltrials.gov identifier: NCT01096082.

Spinocerebellar ataxias in Brazil--frequencies and modulating effects of related genes

This study describes the frequency of spinocerebellar ataxias and of CAG repeats range in different geographical regions of Brazil, and explores the hypothetical role of normal CAG repeats at ATXN1, ATXN2, ATXN3, CACNA1A, and ATXN7 genes on age at onset and on neurological findings. Patients with symptoms and family history compatible with a SCA were recruited in 11 cities of the country; clinical data and DNA samples were collected. Capillary electrophoresis was performed to detect CAG lengths at SCA1, SCA2, SCA3/MJD, SCA6, SCA7, SCA12, SCA17, and DRPLA associated genes, and a repeat primed PCR was used to detect ATTCT expansions at SCA10 gene. Five hundred forty-four patients (359 families) were included. There were 214 SCA3/MJD families (59.6 %), 28 SCA2 (7.8 %), 20 SCA7 (5.6 %), 15 SCA1 (4.2 %), 12 SCA10 (3.3 %), 5 SCA6 (1.4 %), and 65 families without a molecular diagnosis (18.1 %). Divergent rates of SCA3/MJD, SCA2, and SCA7 were seen in regions with different ethnic backgrounds. 64.7 % of our SCA10 patients presented seizures. Among SCA2 patients, longer ATXN3 CAG alleles were associated with earlier ages at onset (p < 0.036, linear regression). A portrait of SCAs in Brazil was obtained, where variation in frequencies seemed to parallel ethnic differences. New potential interactions between some SCA-related genes were presented.

A randomized, phase 2 clinical trial of lithium carbonate in Machado-Joseph disease

BACKGROUND

Because lithium exerts neuroprotective effects in preclinical models of polyglutamine disorders, our objective was to assess the safety and efficacy of lithium carbonate (0.5-0.8 milliequivalents per liter) in patients with Machado-Joseph disease (spinocerebellar ataxia type 3 [MJD/SCA3]).

METHODS

For this phase 2, single-center, double-blind, parallel, placebo-controlled trial (ClinicalTrials.gov identifier NCT01096082), 62 patients who had MJD/SCA3 with a disease duration ≤10 years and an independent gait were randomly assigned (1:1) to receive either lithium or placebo.

RESULTS

After 24 weeks, 169 adverse events were reported, including 50.3% in the lithium group (P = 1.00; primary safety outcome). Sixty patients (31 in the placebo group and 29 in the lithium group) were analyzed for efficacy (intention-to-treat analysis). Mean progression between groups did not differ according to scores on the Neurological Examination Score for the Assessment of Spinocerebellar Ataxia (NESSCA) after 48 weeks (-0.35; 95% confidence interval, -1.7 to 1.0; primary efficacy outcome). The lithium group exhibited minor progression on the PATA speech-rate (P = 0.002), the nondominant Click Test (P = 0.023), the Spinocerebellar Ataxia Functional Index (P = 0.003), and the Composite Cerebellar Functional Score (P = 0.029).

CONCLUSIONS

Lithium was safe and well tolerated, but it had no effect on progression when measured using the NESSCA in patients with MJD/SCA3. This slowdown in secondary outcomes deserves further clarification.

Huntington disease and Huntington disease-like in a case series from Brazil

The aim of this study was to identify the relative frequency of Huntington's disease (HD) and HD-like (HDL) disorders HDL1, HDL2, spinocerebellar ataxia type 2 (SCA2), SCA17, dentatorubral-pallidoluysian degeneration (DRPLA), benign hereditary chorea, neuroferritinopathy and chorea-acanthocytosis (CHAC), in a series of Brazilian families. Patients were recruited in seven centers if they or their relatives presented at least chorea, besides other findings. Molecular studies of HTT, ATXN2, TBP, ATN1, JPH3, FTL, NKX2-1/TITF1 and VPS13A genes were performed. A total of 104 families were ascertained from 2001 to 2012: 71 families from South, 25 from Southeast and 8 from Northeast Brazil. There were 93 HD, 4 HDL2 and 1 SCA2 families. Eleven of 104 index cases did not have a family history: 10 with HD. Clinical characteristics were similar between HD and non-HD cases. In HD, the median expanded (CAG)n (range) was 44 (40-81) units; R(2) between expanded HTT and age-at-onset (AO) was 0.55 (p=0.0001, Pearson). HDL2 was found in Rio de Janeiro (2 of 9 families) and Rio Grande do Sul states (2 of 68 families). We detected HD in 89.4%, HDL2 in 3.8% and SCA2 in 1% of 104 Brazilian families. There were no cases of HDL1, SCA17, DRPLA, neuroferritinopathy, benign hereditary chorea or CHAC. Only six families (5.8%) remained without diagnosis.

Structure-mutagenicity relationship of kaurenoic acid from Xylopia sericeae (Annonaceae)

Kaurane diterpenes are considered important compounds in the development of new highly effective anticancer chemotherapeutic agents. Genotoxic effects of anticancer drugs in non-tumour cells are of special significance due to the possibility that they induce secondary tumours in cancer patients. In this context, we evaluated the genotoxic and mutagenic potential of the natural diterpenoid kaurenoic acid (KA), i.e. (-)-kaur-16-en-19-oic acid, isolated from Xylopia sericeae St. Hill, using several standard in vitro and in vivo protocols (comet, chromosomal aberration, micronucleus and Saccharomyces cerevisiae assays). Also, an analysis of structure-activity relationships was performed with two natural diterpenoid compounds, 14-hydroxy-kaurane (1) and xylopic acid (2), isolated from X. sericeae, and three semi-synthetic derivatives of KA (3-5). In addition, considering the importance of the exocyclic double bond (C16) moiety as an active pharmacophore of KA cytotoxicity, we also evaluated the hydrogenated derivative of KA, (-)-kauran-19-oic acid (KAH), to determine the role of the exocyclic bond (C16) in the genotoxic activity of KA. In summary, the present study shows that KA is genotoxic and mutagenic in human peripheral blood leukocytes (PBLs), yeast (S. cerevisiae) and mice (bone marrow, liver and kidney) probably due to the generation of DNA double-strand breaks (DSB) and/or inhibition of topoisomerase I. Unlike KA, compounds 1-5 and KAH are completely devoid of genotoxic and mutagenic effects under the experimental conditions used in this study, suggesting that the exocyclic double bond (C16) moiety may be the active pharmacophore of the genetic toxicity of KA.

DNA damage in tissues and organs of mice treated with diphenyl diselenide

Diphenyl diselenide (DPDS) is an organoselenium compound with interesting pharmacological activities and various toxic effects. In previous reports, we demonstrated the pro-oxidant action and the mutagenic properties of this molecule in bacteria, yeast and cultured mammalian cells. This study investigated the genotoxic effects of DPDS in multiple organs (brain, kidney, liver, spleen, testes and urinary bladder) and tissues (bone marrow, lymphocytes) of mice using in vivo comet assay, in order to determine the threshold of dose at which it has beneficial or toxic effects. We assessed the mechanism underlying the genotoxicity through the measurement of GSH content and thiobarbituric acid reactive species, two oxidative stress biomarkers. Male CF-1 mice were given 0.2-200 micromol/kg BW DPDS intraperitonially. DPDS induced DNA damage in brain, liver, kidney and testes in a dose response manner, in a broad dose range at 75-200 micromol/kg with the brain showing the highest level of damage. Overall, our analysis demonstrated a high correlation among decreased levels of GSH content and an increase in lipid peroxidation and DNA damage. This finding establishes an interrelationship between pro-oxidant and genotoxic effects. In addition, DPDS was not genotoxic and did not increase lipid peroxidation levels in any organs at doses < 50 micromol/kg. Finally, pre-treatment with N-acetyl-cysteine completely prevented DPDS-induced oxidative damage by the maintenance of cellular GSH levels, reinforcing the positive relationship of DPDS-induced GSH depletion and DNA damage. In summary, DPDS induces systemic genotoxicity in mammals as it causes DNA damage in vital organs like brain, liver, kidney and testes.