Autosomal recessive spinocerebellar ataxia SCAR8/ARCA1: first families detected in Spain

INTRODUCTION

Autosomal recessive spinocerebellar ataxia type 8 (ARCA1/SCAR8) is caused by mutations of the SYNE1 gene. The disease was initially described in families from Quebec (Canada) with a phenotype of pure cerebellar syndrome, but in recent years has been reported with a more variable clinical phenotype in other countries. Cases have recently been described of muscular dystrophy, arthrogryposis, and cardiomyopathy due to SYNE1 mutations.

OBJECTIVE

To describe clinical and molecular findings from 4 patients (3 men and one woman) diagnosed with ARCA1/SCAR8 from 3 Spanish families from different regions.

MATERIAL AND METHODS

We describe the clinical, paraclinical, and genetic results from 4 patients diagnosed with ARCA1/SCAR8 at different Spanish neurology departments.

RESULTS

Onset occurred in the third or fourth decade of life in all patients. After 15 years of progression, 3 patients presented pure cerebellar syndrome, similar to the Canadian patients; the fourth patient, with over 30 years' progression, presented vertical gaze palsy, pyramidal signs, and moderate cognitive impairment. In all patients, MRI studies showed cerebellar atrophy. The genetic study revealed distinct pathogenic SYNE1 mutations in each family.

CONCLUSIONS

ARCA1/SCAR8 can be found worldwide and may be caused by many distinct mutations in the SYNE1 gene. The disease may manifest with a complex phenotype of varying severity.

Autosomal recessive spinocerebellar ataxia SCAR8/ARCA1: First families detected in Spain

INTRODUCTION

Autosomal recessive spinocerebellar ataxia type 8 (ARCA1/SCAR8) is caused by mutations of the SYNE1 gene. The disease was initially described in families from Quebec (Canada) with a phenotype of pure cerebellar syndrome, but in recent years has been reported with a more variable clinical phenotype in other countries. Cases have recently been described of muscular dystrophy, arthrogryposis, and cardiomyopathy due to SYNE1 mutations.

OBJECTIVE

To describe clinical and molecular findings from 4 patients (3 men and one woman) diagnosed with ARCA1/SCAR8 from 3 Spanish families from different regions.

MATERIAL AND METHODS

We describe the clinical, paraclinical, and genetic results from 4 patients diagnosed with ARCA1/SCAR8 at different Spanish neurology departments.

RESULTS

Onset occurred in the third or fourth decade of live in all patients. After 15 years of progression, 3 patients presented pure cerebellar syndrome, similar to the Canadian patients; the fourth patient, with over 30 years' progression, presented vertical gaze palsy, pyramidal signs, and moderate cognitive impairment. In all patients, MRI studies showed cerebellar atrophy. The genetic study revealed distinct pathogenic SYNE1 mutations in each family.

CONCLUSIONS

ARCA1/SCAR8 can be found worldwide and may be caused by many distinct mutations in the SYNE1 gene. The disease may manifest with a complex phenotype of varying severity.

Spinocerebellar ataxia 36 (SCA36): «Costa da Morte ataxia»

INTRODUCTION-OBJECTIVE

To describe the history of the discovery of SCA36 and review knowledge of this entity, which is currently the most prevalent hereditary ataxia in Galicia (Spain) owing to a founder effect.

DEVELOPMENT

SCA36 is an autosomal dominant hereditary ataxia with late onset and slow progression. It presents with cerebellar ataxia, sensorineural hearing loss, and discrete motor neuron impairment (tongue atrophy with denervation, discrete pyramidal signs). SCA36 was first described in Japan (Asida River ataxia) and in Galicia(Costa da Morte ataxia). The condition is caused by a genetic mutation (intronic hexanucleotide repeat expansion) in the NOP56 gene on the short arm of chromosome 20 (20p13). Magnetic resonance image study initially shows cerebellar vermian atrophy that subsequently extends to the rest of the cerebellum and finally to the pontomedullary region of the brainstem without producing white matter lesions. Peripheral nerve conduction velocities are normal, and sensorimotor evoked potential studies show delayed conduction of stimuli to lower limbs. In patients with hearing loss, audiometric studies show a drop of >40dB in frequencies exceeding 2,500Hz. Auditory evoked potential studies may also show lack of waves I and II.

CONCLUSIONS

Costa da Morte ataxia or SCA36 is the most prevalent SCA in the Spanish region of Galicia. Given the region's history of high rates of emigration, new cases may be diagnosed in numerous countries, especially in Latin America. Genetic studies are now available to patients and asymptomatic carriers. Since many people are at risk for this disease, we will continue our investigations aimed at elucidating the underlying pathogenic molecular mechanisms and discovering effective treatment.

Medical genomics: The intricate path from genetic variant identification to clinical interpretation

The field of medical genomics involves translating high throughput genetic methods to the clinic, in order to improve diagnostic efficiency and treatment decision making. Technical questions related to sample enrichment, sequencing methodologies and variant identification and calling algorithms, still need careful investigation in order to validate the analytical step of next generation sequencing techniques for clinical applications. However, the main foreseeable challenge will be interpreting the clinical significance of the variants observed in a given patient, as well as their significance for family members and for other patients.

Every step in the variant interpretation process has limitations and difficulties, and its quote of contribution to false positive and false negative results. There is no single piece of evidence enough on its own to make firm conclusions on the pathogenicity and disease causality of a given variant.

A plethora of automated analysis software tools is being developed that will enhance efficiency and accuracy. However a risk of misinterpretation could derive from biased biorepository content, facilitated by annotation of variant functional consequences using previous datasets stored in the same or linked repositories. In order to improve variant interpretation and avoid an exponential accumulation of confounding noise in the medical literature, the use of terms in a standard way should be sought and requested when reporting genetic variants and their consequences. Generally, stepwise and linear interpretation processes are likely to overrate some pieces of evidence while underscoring others. Algorithms are needed that allow a multidimensional, parallel analysis of diverse lines of evidence to be carried out by expert teams for specific genes, cellular pathways or disorders.

Membranous nephropathy, leiomyoma and autoimmune myasthenia: more than a coincidence?

Membranous nephropathy (MN) has been associated with several infectious, immunological and malignant conditions, but had only rarely been reported with malignant and other immune disorders in the same patient. We describe the case of a 56-year-old male with MN who was also diagnosed with a gastrointestinal stromal tumour (GIST), myasthenia gravis (MG) and thymic hyperplasia. Thus, we report here for the first time the coincidence of these conditions in the same patient. There was a recurrence of nephrotic syndrome without impairment of renal function 5 years after removal of the GIST (3 years after thymectomy). The possible basis for the relationship between these diseases is discussed, and some common genetic and immune physiopathological pathways are hypothesized.

Cerebrotendinous xanthomatosis in Spain: clinical, prognostic, and genetic survey

BACKGROUND AND PURPOSE

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive disorder caused by mutations in the CYP27A1 gene resulting in sterol-27-hydroxylase deficiency. Current information about CTX is based mainly on case reports, with only few large series reported. Although perceived as a potentially treatable condition, efficacy of chenodeoxycholic acid plus statin therapy remains unclear. To perform a nationwide survey of confirmed cases, with a thorough analysis of genotype-phenotype data and prognostic factors.

METHODS

Retrospective review of the clinical and epidemiological aspects and mutations of all the patients diagnosed since 1992 in the main reference centers for genetic testing of CTX in Spain.

RESULTS

Twenty-five patients from 19 families were identified. An average delay of 19 years was observed between symptom onset and clinical diagnosis. Two main clinical subgroups were recognizable: a classic form (cerebellar and other supratentorial symptoms) and a spinal form (chronic myelopathy). Cholestanol levels did not correlate with clinical presentation, severity or response to therapy. Despite treatment, five patients died during follow-up, one to 4 years after diagnosis. Thirteen different mutations were identified, with a higher frequency of p.R395C in Northwestern Spain and p.R405W in Southern Spain. None of the mutations could be associated with a particular clinical feature combination or prognosis.

CONCLUSIONS

This is the first nationwide extensive series of CTX reported in Spain. The higher number of cases in some areas suggests a possible founder effect. Spinal forms had a less severe prognosis. A delayed diagnosis could contribute to the lack of significant response to treatment.

Cerebrotendinous xanthomatosis in Spain: clinical, prognostic, and genetic survey

BACKGROUND AND PURPOSE

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive disorder caused by mutations in the CYP27A1 gene resulting in sterol-27-hydroxylase deficiency. Current information about CTX is based mainly on case reports, with only few large series reported. Although perceived as a potentially treatable condition, efficacy of chenodeoxycholic acid plus statin therapy remains unclear. To perform a nationwide survey of confirmed cases, with a thorough analysis of genotype-phenotype data and prognostic factors.

METHODS

Retrospective review of the clinical and epidemiological aspects and mutations of all the patients diagnosed since 1992 in the main reference centers for genetic testing of CTX in Spain.

RESULTS

Twenty-five patients from 19 families were identified. An average delay of 19 years was observed between symptom onset and clinical diagnosis. Two main clinical subgroups were recognizable: a classic form (cerebellar and other supratentorial symptoms) and a spinal form (chronic myelopathy). Cholestanol levels did not correlate with clinical presentation, severity or response to therapy. Despite treatment, five patients died during follow-up, one to 4 years after diagnosis. Thirteen different mutations were identified, with a higher frequency of p.R395C in Northwestern Spain and p.R405W in Southern Spain. None of the mutations could be associated with a particular clinical feature combination or prognosis.

CONCLUSIONS

This is the first nationwide extensive series of CTX reported in Spain. The higher number of cases in some areas suggests a possible founder effect. Spinal forms had a less severe prognosis. A delayed diagnosis could contribute to the lack of significant response to treatment.

Call for participation in the neurogenetics consortium within the Human Variome Project

The rate of DNA variation discovery has accelerated the need to collate, store and interpret the data in a standardised coherent way and is becoming a critical step in maximising the impact of discovery on the understanding and treatment of human disease. This particularly applies to the field of neurology as neurological function is impaired in many human disorders. Furthermore, the field of neurogenetics has been proven to show remarkably complex genotype-to-phenotype relationships. To facilitate the collection of DNA sequence variation pertaining to neurogenetic disorders, we have initiated the "Neurogenetics Consortium" under the umbrella of the Human Variome Project. The Consortium's founding group consisted of basic researchers, clinicians, informaticians and database creators. This report outlines the strategic aims established at the preliminary meetings of the Neurogenetics Consortium and calls for the involvement of the wider neurogenetic community in enabling the development of this important resource.

Neurofibromatosis without Neurofibromas: Confirmation of a Genotype-Phenotype Correlation and Implications for Genetic Testing

Neurofibromatosis type 1 (NF1) is a multisystem disease with autosomal dominant inheritance and complete penetrance diagnosed by clinical findings. Cutaneous neurofibromas are present in almost all adult patients in the dermis, epidermis or along the peripheral nerves. Plexiform neurofibromas are subcutaneous or deep lesions involving nerve plexuses or roots. Neurofibromas can degenerate into malignant tumors, with important prognostic implications. NF1 shows a broad clinic variability even within a single family. Exceptions are cases reporting the in-frame microdeletion c.2970_2972delAAT, presenting with the typical pigmentary features of NF1, but no cutaneous or plexiform neurofibromas. We report a patient with a de novo c.2970_2972delAAT mutation who had few café-au-lait spots, only 2 of which measured >15 mm, axillary and submammary freckling, a flat angioma extending over the neck, arm and trunk, a high arched palate, micrognathia, macrocephaly, pes cavus and scoliosis. There was complete absence of observable cutaneous neurofibromas as well as external plexiform neurofibromas. She had had epileptic seizures since childhood; however, a diagnosis of NF1 had not been confirmed until she was 38, partly due to the paucity of characteristic cutaneous stigmata. We confirm the association of the c.2970_2972delAAT mutation in NF1 with a particular clinical phenotype, especially with lack of detectable neurofibromas. For an appropriate management of patients and family counseling, molecular study of the NF1 gene should be considered in patients not fulfilling NIH criteria when other features suggestive of NF1 are present. In the absence of neurofibromas, starting NF1 testing with the screening of exon 17 may be worthwhile.

[Usefulness of cholestanol levels in the diagnosis and follow-up of patients with cerebrotendinous xanthomatosis]

INTRODUCTION

cerebrotendinous xanthomatosis (CTX) is an autosomal recessive disease caused by a deficiency of mitochondrial enzyme sterol 27-hydrolylase. Such a deficiency results in a reduced production of chenodeoxycholic acid and in an increased formation of cholestanol. It is clinically characterized by cataracts, diarrhoea, xanthomas, premature arteriosclerosis and a number of progressive neurological symptoms. Although cholestanol levels are used for the diagnosis of CTX, their correlation with the clinical symptoms and their prognostic usefulness have not been assessed so far.

METHODS

we reviewed 14 CTX patients diagnosed between 1995 and 2008 in two reference centres for the genetic diagnosis of this disorder, whose cholestanol levels had been recorded. We studied the main demographic, clinical and therapeutical data and their correlation with plasma cholestanol levels.

RESULTS

the average cholestanol level at diagnosis was 105.8 μmol/l. These levels did not correlate with any neurological symptoms or with disability at diagnosis scored by the EDSS. After treatment, all patients achieved a significant reduction in plasma cholestanol levels (average reduction of 91 μmol/l in an average follow-up of 34 months), although only one patient remained clinically stable.

CONCLUSIONS

high cholestanol levels are very useful for diagnosis of CTX but they do not have a prognostic value (they do not correlate with severity). Normalisation of cholestanol levels is not always associated with clinical stabilisation. However, follow-up of cholestanol levels can be useful for the dose adjustment.

Genetic counselling in neurology: a complex problem that requires regulation

INTRODUCTION

The generalization of genetic studies is transforming the practice of Neurology and confronts the clinical departments with new challenges, such as the organization of genetic counseling. The requirement of specialized knowledge, both clinical and molecular, as well as the need for psychological evaluation and family support, especially for predictive testing and reproductive planning, makes a multidisciplinary approach mandatory.

DEVELOPMENT

The main characteristics of genetic neurodegenerative diseases are the high level of required specialization - since these disorders are often rare and of difficult diagnosis - together with a generally progressive course, unavailability of effective treatment, the issues generated by predictive testing and the interpretation of genetic testing. The aim of genetic counseling is to provide sufficient and objective information for each individual to make their own decision on genetic testing. It must touch upon psychological aspects and family communication. The PICOGEN program from the Clinic Hospital in Barcelona for genetic testing and counseling of dementias is a good example of integrated strategy capable of managing this new clinical scenario in neurology. Unfortunately, this program is an exception in Spain and the patients with neurogenetic disorders and their families usually do not have guaranteed access to an appropriate care.

CONCLUSIONS

Genetic counseling is a unique clinical activity that requires provision of enough time, space and resources to be developed. It implies multidisciplinary participation, due attention to psychological and family issues, and cannot be carried out adequately in a routine Neurology clinic. Legislation is needed to promote a correct articulation of genetic counseling in our country with guarantee of quality and equity. This includes training of the necessary health professionals, clarification of competences and provision of resources to the institutions for the development of such programs.

Practical guidelines addressing ethical issues pertaining to the curation of human locus-specific variation databases (LSDBs)

More than 1,000 Web-based locus-specific variation databases (LSDBs) are listed on the Website of the Human Genetic Variation Society (HGVS). These individual efforts, which often relate phenotype to genotype, are a valuable source of information for clinicians, patients, and their families, as well as for basic research. The initiators of the Human Variome Project recently recognized that having access to some of the immense resources of unpublished information already present in diagnostic laboratories would provide critical data to help manage genetic disorders. However, there are significant ethical issues involved in sharing these data worldwide. An international working group presents second-generation guidelines addressing ethical issues relating to the curation of human LSDBs that provide information via a Web-based interface. It is intended that these should help current and future curators and may also inform the future decisions of ethics committees and legislators. These guidelines have been reviewed by the Ethics Committee of the Human Genome Organization (HUGO). Hum Mutat 31:–6, 2010. © 2010 Wiley-Liss, Inc.

[Disorders affecting the emotional sphere and impulse control in Parkinson's disease]

INTRODUCTION

Parkinson's disease (PD) is associated with mood and behavioral symptoms contributing to morbidity and reduced quality of life of the patients. Most characteristic are depression, anxiety and impulse control disorder.

DEVELOPMENT

Identification and treatment of neuropsychiatric symptoms is necessary for an appropriate management of PD. Affective symptoms may be the initial manifestation of PD, are highly prevalent and pathogenically complex. Impulse control disorders are usually not a spontaneous complaint, so asking about these symptoms may be the only way to detect and treat a serious socio-familial problem. Pharmacological treatment of these manifestations is difficult to balance with an adequate control of motor symptoms. Psychological support from early stages and throughout the evolution of PD is fundamental.

CONCLUSIONS

Neurologist and other healthcare professionals treating PD patients need to be aware of behavioral and emotional manifestations of the disease. This will lead to an appropriate patient management and better adaptation of the familial and social situation.

Association study of the serotoninergic system in migraine in the Spanish population

In order to evaluate the contribution of 19 serotonin-related genes to the susceptibility to migraine in a Spanish population we performed a case-control association study of 122 single nucleotide polymorphisms (SNPs), selected according to genetic coverage parameters, in 528 migraine patients -308 with migraine without aura (MO) and 220 with migraine with aura (MA)- and 528 sex-matched migraine-free controls. The single-marker analysis identified nominal associations with the migraine phenotype or with the MO or MA subtypes. The multiple-marker analysis revealed risk haplotypes in three genes that remained significantly associated with migraine after correction by permutations. Two-marker risk haplotypes were identified in the HTR2B (rs16827801T-rs10194776G) and MAOA (rs3027400G-rs2072743C) genes conferring susceptibility to MO, and a four-marker haplotype in DDC was specific of MA (rs2329340A-rs11974297C-rs2044859T-rs11761683G). The present study supports the involvement of HTR2B and MAOA genes in the genetic predisposition to MO, while DDC might confer susceptibility to MA. These results suggest a differential involvement of serotonin-related genes in the genetic background of MO and MA.

Clinical picture of a patient with a novel PSEN1 mutation (L424V)

Young onset dementia raises concern about familial and non degenerative dementias. We describe a patient with early dementia. At the age of 26, a woman developed symptoms of anorexia nervosa, at 30 a memory and attention deficit, and at 34 abnormal behavior with impulsivity, aggression, and dysexecutive disorder. At 36 she showed aphasia, stereotyped behavior, hyperreflexia, grasping reflex, urinary incontinence, myoclonus, and seizures. Blood and cerebrospinal fluid were normal. Brain computed tomography and single photon emission computed tomography showed diffuse cortico-subcortical atrophy and frontotemporoparietal hypoperfusion. A Leu424Val mutation was present in PSEN1 gene. PSEN1 mutations can produce Alzheimer's disease, frontotemporal dementia, and dementia with Lewy bodies phenotypes, or a combination of them. It has been proposed that the mutation type and location may influence the molecular pathogenesis and thus PSEN1 would represent a molecular connexion between these entities. This case shows a novel PSEN1 mutation with outstanding amnesic and frontal symptoms.

[Behavioral disorders in Parkinson's disease. Genetic, pharmacological and medico-legal aspects]

INTRODUCTION

Patients with Parkinson's disease (PD) may present neuropsychiatric and conduct disorders at different stages of the development of the disease that make treatment even more difficult.

DEVELOPMENT

The neurologist must be on the lookout for the possible appearance of alterations affecting impulse control, even from the early stages of the disease, so as to be able to prevent them or to plan a suitable adjustment of treatment. Some of the most common impulsivity disorders include hypersexuality, compulsive gambling and other addictive behaviours which, if left undetected and untreated, can end up having a destructive effect on the patient's socio-familial surroundings. Psychotic disorders (hallucinations, delusions) are often associated to advanced phases of PD and to the effect of dopamine therapy, and they are associated to a higher morbidity and mortality rate. Factors of a genetic or pharmacogenetic nature or a gene-environment interaction may account for the different individual susceptibility to disorders in the neuropsychiatric realm among patients with PD. It is wise to bear in mind the possible medico-legal implications that may stem from behavioral disorders, both for the patient and his or her family and for the physician, because situations could arise that trigger conflicts between confidentiality and preventing third parties from being harmed, as well as harm that can be attributed to the side effects of medicines.

CONCLUSIONS

The specialist must be familiar with, foresee and propose suitable treatment for behavioral and neuropsychiatric disorders in PD with potential medico-legal implications.

Analysis of candidate genes at the IBGC1 locus associated with idiopathic basal ganglia calcification ("Fahr's disease")

Basal ganglia calcification (striatopallidodentate calcifications) can be caused by several systemic and neurological disorders. Familial Idiopathic Basal Ganglia Calcification (IBGC, "Fahr's disease"), is characterized by basal ganglia and extrabasal ganglia calcifications, parkinsonism and neuropsychiatric symptoms. Because of an increased use of neuroimaging procedures, calcifications of the basal ganglia are visualized more often and precociously. In 1999, a major American family with IBGC was linked to a locus on chromosome 14q (IBGC1). Another small kindred, from Spain, has also been reported as possibly linked to this locus. Here we report the main findings of the first 30 candidate genes sequenced at the IBGC1 locus during the process of searching for a mutation responsible for familial IBGC. During the sequencing process, we identified a heterozygous nonsynonymous single nucleotide polymorphism (exon 20 of the MGEA6/c-TAGE gene) shared by the affected and not present in the controls. This SNP was randomly screened in the general population (348 chromosomes) in a minor allele frequency to 0.0058 (two heterozygous among 174 subjects). Another variation in this gene, in the exon 9, was found in the Spanish family. However, this variation was extremely common in the general population. Functional and population studies are necessary to fully access the implications of the MGEA6 gene in familial IBGC, and a complete sequencing of the IBGC1 locus will be necessary to define a gene responsible for familial IBGC.

Genetic heterogeneity in familial idiopathic basal ganglia calcification (Fahr disease)

Familial idiopathic basal ganglia calcification (IBGC, Fahr disease) is an inherited neurologic condition characterized by basal ganglia and extra-basal ganglia brain calcifications, parkinsonism, and neuropsychiatric symptoms. The authors examined six families for linkage to the previously identified genetic locus (IBGC1) located on chromosome 14q. The authors found evidence against linkage to IBGC1 in five of the six families supporting previous preliminary studies demonstrating genetic heterogeneity in familial IBGC.

Autosomal dominant congenital fibre type disproportion: a clinicopathological and imaging study of a large family

Congenital fibre type disproportion (CFTD) is considered a non-progressive or slowly progressive muscle disease with relative smallness of type 1 fibres on pathological examination. Although generally benign, CFTD has a variable natural course and severe progression has been observed in some patients. The pathogenesis of the disorder is unknown and many authors consider CFTD a syndrome with multiple aetiologies rather than a separate clinical entity. A positive family history has been reported in about 40% of cases, but the inheritance pattern is not clear. Both autosomal recessive and dominant modes of inheritance have been suggested. The present paper describes a large, multigenerational kindred that has an inherited myopathy fulfilling the histological criteria of CFTD, with autosomal dominant transmission and high penetrance. The clinical picture, remarkably similar in all affected family members, started in early infancy with mild limb muscle weakness. There was slow progression of symptoms into adulthood, with moderate to severe, mainly proximal, muscle weakness without loss of ambulation. Muscle biopsy from two affected individuals demonstrated predominance of small type 1 muscle fibres without other significant findings. Nerve conduction studies were normal and needle electromyography showed a myopathic pattern. MRI examination performed on three patients from successive generations showed involvement of proximal limb and paraspinal muscles. The clinical and pathological homogeneity in the present family, together with the lack of additional histological abnormalities after decades of disease progression in two affected individuals, supports this being a distinct myopathy with fibre type disproportion. Whether the disease in this family can be regarded as a form of the congenital myopathy known as CFTD or rather a unique condition sharing histological features with CFTD needs further investigation. This is, to our knowledge, the largest kindred with muscle fibre type disproportion reported to date. Our data confirm autosomal dominant inheritance, and this is the first MRI document of this disorder.

Rare HRAS1 alleles are a risk factor for the development of brain tumors

BACKGROUND

The highly polymorphic HRAS1 minisatellite locus, located 1 kilobase downstream from the H-ras1 gene, has been associated with increased susceptibility to a variety of cancers. Microsatellite instability (MI), another molecular abnormality observed in human neoplasms, most likely reflects an increased mutation rate and also is thought to underlie cancer predisposition. The purpose of this study was to investigate the association between rare HRAS1 alleles and brain tumors and to correlate the HRAS1 allelotype with MI and clinicopathologic features.

METHODS

Ninety-four patients with primary brain tumors (52 gliomas, 32 meningiomas, and 10 schwannomas) and 109 healthy control individuals were studied. The size of HRAS1 alleles was determined by fluorescent detection in an automated DNA sequencer. The interspersion pattern was assessed by the minisatellite variant repeat-polymerase chain reaction technique.

RESULTS

Twenty of 94 (21.28%) patients with brain tumors had at least one rare allele, compared with 13 of 109 (11.92%) in the control population (Fisher exact test; P = 0.0329). The presence of rare alleles was associated with an increased risk of brain tumors (odds ratio, 1.99; 95% confidence interval, 0.93-4.27). The overrepresentation of rare alleles in tumor patients mainly reflects the higher frequency observed in the glioma group (P = 0.0086). The authors did not detect association between the presence of rare HRAS1 alleles and MI in their series. No significant difference in the distribution of these alleles was found when tumors were compared according to other clinicopathologic variables.

CONCLUSIONS

The presence of rare HRAS1 alleles is associated with an increased risk for the development of glial neoplasms (OR = 2.72; 95% CI, 1.17-6.32). The lack of association between rare HRAS1 polymorphisms and MI suggests that these two genetic factors are not likely to be expression of the same underlying defect.

The SCA12 mutation as a rare cause of spinocerebellar ataxia

BACKGROUND

Spinocerebellar ataxias are a group of phenotypically and genetically heterogeneous disorders characterized by progressive degeneration of the cerebellum. The expansion of a CAG repeat upstream of the PP2APR55beta gene has been recently reported as a novel cause of a dominantly inherited ataxia (SCA12) in a kindred with limb tremor as an early feature.

OBJECTIVE

To explore the relative frequency of SCA12 among familial and sporadic spinocerebellar ataxias in an ethnically diverse patient population.

METHODS

We used polymerase chain reaction to analyze CAG repeat size in a series of patients presenting to an ataxia clinic in California.

RESULTS

The SCA12 expansion was not detected in any of the cases investigated. The largest allele found had 22 repeats, a finding within the proposed nonpathogenic range. Distribution of repeat size and heterozygosity were similar to that described previously.

CONCLUSIONS

These results, coupled with findings in other populations, indicate that the SCA12 mutation is a rare cause of spinocerebellar degeneration. Diagnostic testing for SCA12 should be considered in patients with cerebellum disorders and an atypical clinical phenotype, especially when tremor is initially present.

SCA8 repeat expansions in ataxia: a controversial association

The observation of large SCA8 alleles in healthy control subjects and nonataxic patients, together with a lack of segregation of the expanded repeat with ataxia in several families, has raised questions about the pathogenic role of the SCA8 expansion. The authors found allele sizes within the proposed pathogenic range in three patients with ataxia of unknown etiology, in two individuals from pedigrees with either SCA2 or Friedreich's ataxia, and in two patients with Alzheimer's disease. Sizing of SCA8 alleles should not be a routine diagnostic test until its etiologic role is clarified and the pathogenic threshold is determined.

Analysis of 2 antiapoptotic factors in gliomas: bcl-2 overexpression and p53 mutations

BACKGROUND

p53 mutations and immunoreactivity have been described in human gliomas. During the past few years, some authors have found bcl-2 overexpression in astrocytomas, although their correlation with histological grade is a matter of disagreement. A relation between bcl-2 overexpression and p53 immunoreactivity has also been suggested.

OBJECTIVES

To analyze the frequency of presentation of bcl-2 and p53, their clinicopathologic implications, and their possible coexpression.

METHODS

We studied p53 and bcl-2 with immunohistochemical and molecular methods in 61 gliomas (including 21 astrocytomas, 9 anaplastic astrocytomas, 29 glioblastomas, 1 oligodendroglioma, and 1 mixed glioma).

RESULTS

We discovered a high level of bcl-2 overexpression (57%). Overexpression of bcl-2 can be an early event in gliomas tumorigenesis, although no correlation was found with any of the clinicopathologic parameters studied. p53 mutations were present in a small proportion of gliomas (17%). p53 immunoreactivity was present in 34 cases (57%), and it was related to histological grade and a supratentorial location. A high percentage of tumors (26 cases, 42%) presented p53 immunoreactivity without p53 mutations.

CONCLUSIONS

Since there was no relation between bcl-2 overexpression and p53 mutations or p53 immunoreactivity, both factors may not act together in the genesis and evolution of gliomas.

Value of MIB-1 labelling index (LI) in gliomas and its correlation with other prognostic factors. A clinicopathologic study

BACKGROUND

In recent years, the monoclonal antibody MIB-1 has become the main factor to measure the proliferative potential of glial tumors. This antibody is equivalent to Ki-67, which is used in frozen sections, and reacts with a nuclear protein that is expressed through the cell cycle. We have investigated the value of MIB-1 Labelling Index (LI) as an independent prognostic factor in gliomas and its relationship with clinical and pathological parameters.

METHODS

MIB-1 LI was determined in 139 gliomas by using the Streptavidin-Biotin Complex (SBC) immunohistochemical method. MIB-1 LI immunoreactivity was measured with an automatic cell counting system. Survival was studied by using the Kaplan-Meier bivariant analysis and Cox multivariant regression.

RESULTS

In bivariant analysis MIB-1 LI increased with age, histological grade and a supratentorial lateral location. Only size and tumor grade were significant in Cox regression.

CONCLUSIONS

Perhaps this proliferation marker is influenced by many factors which reduce its value as an isolated prognostic parameter.

Low frequency of replication errors in primary nervous system tumours

OBJECTIVES

Automated DNA technology was used to analyze the incidence of microsatellite instability (MIN) among the most frequent types of adult primary CNS tumours and to determine its relation with clinicopathological characteristics.

METHODS

Fifty six gliomas, 32 meningiomas and 11 schwannomas were screened for size changes at eight microsatellite loci using fluorescent polymerase chain reaction (PCR) followed by fragment analysis in an automated sequencer. A tumour was considered as MIN+ when a different electrophoretic pattern between constitutional and tumour DNA was evidenced in one or more microsatellite markers and as replication error positive (RER+) when at least 25% of the markers analyzed (2/8) showed instability. The MIN phenotype was correlated with relevant clinical and pathological parameters.

RESULTS

Globally, instability was found in 19/767 analyses (2.47%), with a higher rate among tetranuceotide than dinucleotide repeats (chi(2) test, p=0.018). Ten gliomas (17.9%), two meningiomas (6.3%), and two schwannomas (18.2%) were MIN+, whereas one glioma (1.8%), two meningiomas (6.3%), and one schwannoma (9.1%) were classified as RER+. A possible association between microsatellite instability and a shorter duration of clinical course was found in meningiomas. The MIN+ phenotype was more frequent in spinal than intracranial schwannomas (Fisher's exact test, p=0.018). No other significant association with clinical or histological features was detected.

CONCLUSIONS

Although microsatellite instability can be demonstrated at a low rate in some primary CNS tumours, a true replication error phenotype (revealed by widespread microsatellite instability at numerous loci) is uncommon and unlikely to play an important part in the pathogenesis of these neoplasms. This form of instability was more frequent in tetranucleotide than in dinucleotide repeats. To our knowledge, this is the first report of MIN in schwannomas, where it was associated with the spinal localisation of the tumour.

Assessing microsatellite instability with semiautomated fluorescent technology: application to the analysis of primary brain tumors

The replication error phenotype, revealed by the observation of widespread microsatellite instability (MIN), has been identified as a new mechanism of cancer susceptibility, and the comparison of the allele sizes of polymorphic microsatellite repeats between normal and tumor DNA is now frequently undertaken in colorectal and other human neoplasias. The lack of precise characterization of the electrophoretic profiles of microsatellites is one of the main sources of discord between the rate of MIN reported for the same type of tumor by different investigators. The recent introduction of fluorescent-based semiautomated microsatellite analysis allows a more accurate size comparison, but one or more artificial peaks, generated during polymerase chain reaction (PCR) and/or electrophoresis, are frequently detected along with the true allele peaks. The aim of this study was to characterize the most frequent artificial extra peaks in the short tandem repeats (STRs) used by us to assess MIN in human cancers. We analyzed eight microsatellite loci in 113 primary brain tumors. HumFibra/FGA exhibited the most frequent extra peak formation. For each microsatellite there is a characteristic pattern of artifact formation which must be recognized to avoid a false-positive diagnosis of MIN.

[Familial strio-pallido++-dentate calcification]

INTRODUCTION

Calcification of the dentate nucleus of the cerebellum may be seen on cerebral CT in 0.3-0.5% of patients with no symptoms or extra-pyramidal signs. Although there are many causes, some cases show a family incidence. Clinical cases. We present two cases, mother and son, in whom the predominant clinical findings were poor language and a bilateral extrapyramidal syndrome. Laboratory tests, hormone and immunological studies were normal. In both patients cerebral CT showed bilateral calcification of the basal nuclei and dentate nuclei of the cerebellum.

DISCUSSION

Our patients fulfilled the clinical and neuro-imaging criteria described in familial strio-pallido-dentate calcification. There is no relationship between the duration and intensity of symptoms, and the extension of the calcification. However, all patients with calcification show clinical features. The predominant features are poor language and a bilateral extra-pyramidal syndrome. These observations indicate that in patients with calcification of the basal ganglia and dentate nuclei of the cerebellum it is necessary to study first degree relatives in order to identify the condition.

[Cerebral hemorrhage and migraine]

The connection between migraine and brain haemorrhage is controversial. We present the case of eight nonhypertense patients all aged under 57 with migraine antecedents who suffered brain haemorrhage during an attack. All underwent analytical study, chest X-ray, electrocardiography, computerized tomography scan and brain panangiography. The study was completed in six cases with an immunological analysis and in a further five with brain magnetic resonance. Seven patients habitually took vasoactive drugs to relieve migraine. The results do not show any other cause of brain haemorrhage. It is possible haemorrhage may be related to vascular lesion brought about by ischaemia secondary to vasospasms.