Hereditary ataxias: epidemiological aspects

Hereditary ataxias, hereditary spastic paraplegia and Charcot-Marie-Tooth syndrome (HA) are chronic progressive neurological diseases. Epidemiologic studies of these disorders are few. In a geographically well-defined Danish population, we present incidence rates, cumulated incidence rates and prevalence for patients with HA based on modern continuous-time survival analysis techniques. From these, prevalence has been estimated to be 6.06 per 10(5) in the 10 to 50-year-old population. Combined risk of HA was found to be 0.16% for women and 0.20% for men up to their 51st birthday.     

A genetic epidemiological study of spinocerebellar ataxias in Tottori prefecture, Japan

We investigated the genotype frequencies of patients with spinocerebellar ataxias (SCA), using a community-based prevalence study among 613,349 inhabitants in Tottori prefecture, Japan. Prevalence date was April 1, 1998. On this date, 109 SCA patients were identified in this community. The prevalence of SCA was 17.8 per 100,000 individuals. The most common cause of inherited SCA was a mutation at the SCA6 locus (25%), followed by mutation at the SCA1 locus (15%), SCA3 locus (5%) and dentatorubral-pallidoluysian atrophy locus (5%). None of the expanded alleles was found in SCA2, SCA7 or Friedreich's ataxia. Mutation at SCA6 was also the most common form of sporadic SCA at 11%. Prevalences per 100,000 individuals were as follows: SCA6, 2.40; SCA1, 0.48; DRPLA, 0.32, and SCA3, 0.16.     

Hereditary ataxias, spastic parapareses and neuropathies in Eastern Canada

It has been demonstrated, for many inherited diseases, that historical events have shaped the various regional gene pools of Eastern Canada. In so doing, it has given rise to the increased prevalence of some rare diseases due, to founder effects. The following neurogenetic disorders were first identified in patients from Eastern Canada: AOA-2, Arsacs, HSN-2, Arca-1, HMSN/ACC and Arsal. The population of Eastern Canada, we are convinced, will still allow the identification of new rare forms of hereditary ataxias, spastic parapareses and neuropathies as well as contribute to the uncovering of their mutated genes. We have summarized our current knowledge of the various hereditary ataxias, spastic parapareses and neuropathies in Eastern Canada. The study of the more common and homogenous features of these diseases has been largely completed.     

Sleep habits of students attending elementary schools,and junior and senior high schools in Akita prefecture

It is widely accepted that students in Japan sleep fewer hours than what they actually need. However, epidemiological data on sleep habits among students are scarce. The sleep habits and related problems among 1650 students in Akita prefecture were studied. The results revealed that schoolchildren attending elementary schools seemed to sleep for a sufficient number of hours, whereas students attending junior or senior high schools were not sleeping enough. In particular, approximately half of the students attending senior high schools answered that they slept 6 h or less on weekdays and nodded off during classes more than twice a week.     

Hereditary chorea--update]

Understanding molecular genetical background of hereditary chorea has recently been progressed so far. Triplet repeat expansion diseases including, Huntington disease, in which CAG expansion has been identified in the IT-15 or Huntingtin gene, and Huntington disease like-2, in which CTG expansion in junctophilin-3 (JPH3) gene occurs, causes selective degeneration of striatum in the brain. Octapeptide repeat expansion in the prion gene in Huntington disease like-1 has been also identified. Neuroacanthocytosis syndromes including McLeod syndrome and chorea-acanthocytosis cause acanthocytosis in the red blood cells and chorea due to the degeneration of caudate nucleus in the brain. The XK gene on the X chromosome is mutated to lose its function in McLeod syndrome. CHAC gene coding chorein is mutated to lead loss of function in chorea-acanthocytosis. Selective degeneration in the striatum, especially in the caudate nucleus might be associated with the molecular cascade of expanded polyglutamine or polyleucine or octapeptide and the loss of function of the XK protein and of chorein protein.     

Hereditary ataxias-overview]

Many of autosomal dominant spinocerebellar ataxias (SCA) are now shown to result from the expansion of unstable trinucleotide repeats. In most SCAs, these repeats are present within coding sequences of the causative genes and translated into polyglutamine tracts. In this overview clinical and molecular genetic features of newly identified group of diseases in this category are briefly summarized. Expanded polyglutamine repeats are supposed to mediate some toxic effects on a certain population of neurons that result in neuronal dysfunction. The current progress in these molecular biological studies on their pathophysiology is also reviewed. In Japan, Friedreich ataxia with intoronic GAA repeat expansions has not been known. Instead, early onset ataxia with Friedreich phenotype, associated with ocular motor apraxia in childhood and with hypoalbuminemia in adult, is the predominant ataxia with Friedreich phenotype, the causative mutation of which was very recently identified.     

Hereditary ataxias and paraplegias in Valle ďAosta, Italy: a study of prevalence and disability

Introduction - a study was conducted in the Valle ďAosta Region, Italy, (115270 inhabitants) to determine the prevalence of hereditary ataxias (HA) and hereditary spastic paraplegias (HSP), and the degree of disability they cause. Methods - we identified all patients with suspected HA or HSP referred from 1981 to 1991 to in- and out-patient departments, EEG, EMG, and CT-scan services, and centres for the handicapped. Harding's criteria were followed for diagnosis and classification. Results - at the prevalence day, 17 patients were alive, with a prevalence ratio of 14.8/100000 population. There were 2 cases of Friedreich's ataxia (FA), 1 of early onset cerebellar ataxia with retained tendon reflexes (EOCA), 1 of autosomal dominant cerebellar ataxia (ADCA), 8 of sporadic idiopathic late onset cerebellar ataxias, and 5 of HSP. Conclusions - epidemiological studies on HA and HSP show higly variable prevalence ratios, which could be due in part to the inclusion of sporadic cases. FA, EOCA and ADCA have similar prevalence ratios in most studies.     

Spinocerebellar ataxias

Conventional MRI in patients presenting with progressive ataxia demonstrates the three main patterns of macroscopic damage, namely spinal atrophy, olivopontocerebellar atrophy and cortical cerebellar atrophy. Moreover it contributes to the diagnosis of fragile-X tremor ataxia syndrome and siderosis of the CNS. Non conventional MRI techniques detect nervous tissue abnormalities before development of atrophy which are correlated with the severity of the clinical deficit.     

Hereditary motor and sensory neuropathy]

The report consisted of 10 cases of hereditary motor and sensory neuropathy (HMSN). There were 7 males and 3 females. Their ages ranged from 11 to 42 (average 24.6) years, ages of onset varied from 7 to 34 (average 17.3) years. Hereditary history was showed in 4 cases. The clinical features of all 10 cases had peroneal muscular atrophy, 8 of 10 cases also had involvement of the upper limbs, 7 of 10 cases had pes arcuatus. The conduction velocity was obviously slow in 5 cases and slightly slow in the others. Oion-bulb hypertrophic neuropathy was demonstrated in sural nerve biopsies of 5 cases. Neuronal axonal degeneration were found in the remaining 5 cases. Clinical classification, clinical features and pathological characteristics were discussed.     

The inherited ataxias

Diagnosis and classification of the inherited ataxias are reviewed with emphasis on recognizing treatable disorders. Even when basic defects are untreatable, many complications of the degenerative process are amenable to therapy.     

Physostigmine in familial ataxias

Physostigmine was given to 12 patients with various spincerebellar degenerations, and neurologic examinations were recorded on video tapes and assessed on a semiquantitative scale. Forty minutes after a single dose, the scores improved by 35.7 +/- 4.7 percent (means +/- SEM). Eight patients were then studied over sequential 3-month periods by a randomized double-blind trial of physostigmine versus placebo. With physostigmine, scores were 33.9 +/- 8.3 percent better than before treatment or with placebo. Further investigations of cholinergic drugs seem warranted in patients with these diseases.     

Electroretinographic findings in inherited ataxias

Electroretinogram was performed in 18 patients with inherited ataxias. Eight had Friedreich's disease, 9 autosomal dominant cerebellar ataxia and one early onset cerebellar ataxia with retained tendon reflexes. Abnormalities were found in one patient for each group. The most frequent were decreased b-wave amplitude in photopic and scotopic conditions and prolonged implicit time.     

Movement disorders in spinocerebellar ataxias

Autosomal dominant spinocerebellar ataxias (SCAs) can present with a large variety of noncerebellar symptoms, including movement disorders. In fact, movement disorders are frequent in many of the various SCA subtypes, and they can be the presenting, dominant, or even isolated disease feature. When combined with cerebellar ataxia, the occurrence of a specific movement disorder can provide a clue toward the underlying genotype. There are reasons to believe that for some coexisting movement disorders, the cerebellar pathology itself is the culprit, for example, in the case of cortical myoclonus and perhaps dystonia. However, movement disorders in SCAs are more likely related to extracerebellar pathology, and imaging and neuropathological data indeed show involvement of other parts of the motor system (substantia nigra, striatum, pallidum, motor cortex) in some SCA subtypes. When confronted with a patient with an isolated movement disorder, that is, without ataxia, there is currently no reason to routinely screen for SCA gene mutations, the only exceptions being SCA2 in autosomal dominant parkinsonism (particularly in Asian patients) and SCA17 in the case of a Huntington's disease–like presentation without an HTT mutation. © 2011 Movement Disorder Society     

Network to support patients with ALS in the Hyogo prefecture]

The author reports network to support patients with amyotrophic lateral sclerosis in the Hyogo prefecture. Three types of network are working, which are the network in the multidisciplinary team in the hospital, the medico-welfare network in the area and the network intra-hospitals in the prefecture. We have to establish effective network with a passion, a mission and an action.     

Dominantly inherited ataxias

The autosomal dominant ataxias continue to bewilder us as the enormity of their genetic heterogeneity continues to unfold. The Human Genome Organization website now lists 22 such ataxias, not including dentatorubral-pallidoluysian atrophy. The early genetic discoveries in this field included several disorders caused by CAG repeat expansions within coding regions of the respective genes. More recent discoveries have included unstable expansions of nucleotide repeats in noncoding regions of genes as well as point mutations that have formed the basis of progressive dominant ataxias. This article summarizes the clinical and genetic features of the currently identified dominant ataxias.