[THE ANALYSIS OF LIFE SPAN AND MORTALITY OF PATIENTS WITH SPINOCEREBELLAR ATAXIA TYPE I].

The article presents results of investigation of certain unclear aspects of mortality of patients with spinocerebellar ataxia type I including patients with the same number of CAG-repetitions. The analysis of mortality of patients observed from 1993 to nowadays was implemented. Sampling included 112 patients during that period 53 patients died. The comparative analysis was implemented concerning received data and results of analysis of mortality of patients died prior to 1980. According received data, average value of CAG-repetitions of normal allele was equal to 30.2, and ofpathologic allele--48.7. The average life span made up to 52.8 years, average age of disease onset--38 years and natural duration of disease--14.8 years. The analysis of life span of patients with equal length of repetitions demonstrated that range of life span of patients makes up to from 8 to 23 years. It is established that life of patients becomes shorter because of accidents, cancer and concomitant diseases of cardiovascular system. The presence of such concomitant disease as tuberculosis of lungs results in no shortening of life of patients. The comparative analysis of mortality during the period over 34 years demonstrated that age of disease onset turned out to be more conservative and stable indicator of morbidity. Despite of lacking of effective methods of treatment of disease, the natural duration of disease increased statistically reliable up to 1.8 times during period of observation. The analysis of life span ofpatients with spinocerebellar ataxia type I demonstrated that their life span except length of CAG-expansion depends on a number of factors accelerating and retarding development of disease. At that, life span of patients with the same number of CAG-repetitions can significantly differ The malignant neoplasms, diseases of cardiovascular system and external causes are to be referred to factors accelerating and retarding development of main disease. The addition oftuberculosis in our case resulted in no alteration of natural course of disease. The other factors exist prolonging life of patients, including factors of social economic and medical character They require additional specification and thorough investigation with the purpose of developing methods ofpreventive correction of neuro-degeneration processes.

Missense mutations in desmin associated with familial cardiac and skeletal myopathy.

Desmin-related myopathy (OMIM 601419) is a familial disorder characterized by skeletal muscle weakness associated with cardiac conduction blocks, arrhythmias and restrictive heart failure, and by intracytoplasmic accumulation of desmin-reactive deposits in cardiac and skeletal muscle cells. The underlying molecular mechanisms are unknown. Involvement of the desmin gene (DES) has been excluded in three families diagnosed with desmin-related myopathy. We report two new families with desmin-related cardioskeletal myopathy associated with mutations in the highly conserved carboxy-terminal end of the desmin rod domain. A heterozygous A337P mutation was identified in a family with an adult-onset skeletal myopathy and mild cardiac involvement. Compound heterozygosity for two other mutations, A360P and N393I, was detected in a second family characterized by childhood-onset aggressive course of cardiac and skeletal myopathy.

Fatal familial insomnia and familial Creutzfeldt-Jakob disease: disease phenotype determined by a DNA polymorphism.

Fatal familial insomnia (FFI) and a subtype of familial Creutzfeldt-Jakob disease (CJD), two clinically and pathologically distinct diseases, are linked to the same mutation at codon 178 (Asn178) of the prion protein gene. The possibility that a second genetic component modified the phenotypic expression of the Asn178 mutation was investigated. FFI and the familial CJD subtype segregated with different genotypes determined by the Asn178 mutation and the methionine-valine polymorphism at codon 129. The Met129, Asn178 allele segregated with FFI in all 15 affected members of five kindreds whereas the Val129, Asn178 allele segregated with the familial CJD subtype in all 15 affected members of six kindreds. Thus, two distinct disease phenotypes linked to a single pathogenic mutation can be determined by a common polymorphism.

Disease severity in dominant Emery Dreifuss is increased by mutations in both emerin and desmin proteins.

Individuals with the same genetic disorder often show remarkable differences in clinical severity, a finding generally attributed to the genetic background. We identified two patients with genetically proven Emery-Dreifuss muscular dystrophy (EDMD) who followed an unusual course and had uncommon clinicopathological findings. We hypothesized digenic inheritance and looked for additional molecular explanations. Mutations in additional separate genes were identified in both patients. The first patient was a member of a family with molecularly proven X-linked EDMD. However, the clinical features were unusually severe for this condition in the propositus: he presented at 2.5 years with severe proximal weakness and markedly elevated serum creatine kinase. Muscle weakness rapidly progressed, leading to loss of independent ambulation by the age of 12. In addition, the patient developed cardiac conduction system disease requiring pacing at the age of 11 and severe dilated cardiomyopathy in the early teens. Despite pacing, he had several syncopal episodes attributed to ventricular dysrhythmias. As these resemble the cardiac features of patients with the autosomal dominant variant of EDMD, we examined the lamin A/C gene, identifying a de-novo mutation in the propositus. The second patient had a cardioskeletal myopathy, similar to his mother who had died more than 20 years previously. Because of the dominant family history, a laminopathy was suspected and a mutation in exon 11 of the LMNA gene was identified. This mutation, however, was not present in his mother, but instead, surprisingly, was identified in his virtually asymptomatic father. Unusual accumulations of desmin found in the cardiac muscle of the propositus prompted us to examine the desmin gene in this patient, and in so doing, we identified a desmin mutation, in addition to the LMNA mutation in the propositus. These cases suggest that separate mutations in related proteins that are believed to interact, or that represent different parts of a presumed functional pathway, may synergistically contribute to disease severity in autosomal dominant EDMD. Furthermore, digenic inheritance may well contribute to the clinical severity of many other neuromuscular disorders.

New insights into the protein aggregation pathology in myotilinopathy by combined proteomic and immunolocalization analyses.

INTRODUCTION: Myofibrillar myopathies are characterized by progressive muscle weakness and impressive abnormal protein aggregation in muscle fibers. In about 10 % of patients, the disease is caused by mutations in the MYOT gene encoding myotilin. The aim of our study was to decipher the composition of protein deposits in myotilinopathy to get new information about aggregate pathology. RESULTS: Skeletal muscle samples from 15 myotilinopathy patients were included in the study. Aggregate and control samples were collected from muscle sections by laser microdissection and subsequently analyzed by a highly sensitive proteomic approach that enables a relative protein quantification. In total 1002 different proteins were detected. Seventy-six proteins showed a significant over-representation in aggregate samples including 66 newly identified aggregate proteins. Z-disc-associated proteins were the most abundant aggregate components, followed by sarcolemmal and extracellular matrix proteins, proteins involved in protein quality control and degradation, and proteins with a function in actin dynamics or cytoskeletal transport. Forty over-represented proteins were evaluated by immunolocalization studies. These analyses validated our mass spectrometric data and revealed different regions of protein accumulation in abnormal muscle fibers. Comparison of data from our proteomic analysis in myotilinopathy with findings in other myofibrillar myopathy subtypes indicates a characteristic basic pattern of aggregate composition and resulted in identification of a highly sensitive and specific diagnostic marker for myotilinopathy. CONCLUSIONS: Our findings i) indicate that main protein components of aggregates belong to a network of interacting proteins, ii) provide new insights into the complex regulation of protein degradation in myotilinopathy that may be relevant for new treatment strategies, iii) imply a combination of a toxic gain-of-function leading to myotilin-positive protein aggregates and a loss-of-function caused by a shift in subcellular distribution with a deficiency of myotilin at Z-discs that impairs the integrity of myofibrils, and iv) demonstrate that proteomic analysis can be helpful in differential diagnosis of protein aggregate myopathies.

Desmin splice variants causing cardiac and skeletal myopathy.

Desmin myopathy is a hereditary or sporadic cardiac and skeletal myopathy characterised by intracytoplasmic accumulation of desmin reactive deposits in muscle cells. We have characterised novel splice site mutations in the gene desmin resulting in deletion of the entire exon 3 during the pre-mRNA splicing. Sequencing of cDNA and genomic DNA identified a heterozygous de novo A to G change at the +3 position of the splice donor site of intron 3 (IVS3+3A-->G) in a patient with sporadic skeletal and cardiac myopathy. A G to A transition at the highly conserved -1 nucleotide position of intron 2 affecting the splice acceptor site (IVS2-1G-->A) was found in an unrelated patient with a similar phenotype. Expression of genomic DNA fragments carrying the IVS3+3A-->G and IVS2-1G-->A mutations confirmed that these mutations cause exon 3 deletion. Aberrant splicing leads to an in frame deletion of 32 complete codons and is predicted to result in mutant desmin lacking 32 amino acids from the 1B segment of the alpha helical rod. Functional analysis of the mutant desmin in SW13 (vim-) cells showed aggregation of abnormal coarse clumps of desmin positive material dispersed throughout the cytoplasm. This is the first report on the pathogenic potentials of splice site mutations in the desmin gene.

Genetic studies in relation to kuru: an overview.

Kuru is a subacute neurodegenerative disease presenting with limb ataxia, dysarthria, and a shivering tremor. The disease progress to complete motor and mental incapacity and death within 6 to 24 months. Neuropathologically, a typical pattern of neuronal loss, astrocytic and microglial proliferation, characteristic "kuru-type" amyloid plaques, and PrP deposits in the cerebral cortex and cerebellum are observed. Kuru is the prototype of a group of human transmissible spongiform encephalopathies (TSEs), or "prion" diseases, that include hereditary, sporadic and infectious forms. The latest member of this group, the variant Creutzfeldt-Jakob disease (vCJD), linked to transmission of bovine spongiform encephalopathy (BSE) to humans, shows features similar to kuru. Kuru has emerged at the beginning of the 1900s in a small indigenous population of New-Guinean Eastern Highlands, reached epidemic proportions in the mid-1950s and disappeared progressively in the latter half of the century to complete absence at the end of the 1990s. Early studies made infection, the first etiologic assumption, seem unlikely and led to a hypothesis that kuru might be a genetically determined or genetically mediated illness. After transmissibility of kuru had been discovered and all major epidemiologic phenomena adequately explained by the spread of an infectious agent with long incubation period through the practice of cannibalism, the pattern of occurrence still continued to suggest a role for genetic predisposition. Recent studies indicate that individuals homozygous for Methionine at a polymorphic position 129 of the prion protein were preferentially affected during the kuru epidemic. The carriers of the alternative 129Met/Val and 129Val/Val genotypes had a longer incubation period and thus developed disease at a later age and at a later stage of the epidemic. Observations made during the kuru epidemic are helpful in the understanding of the current vCJD outbreak, and vice versa clinical and experimental data accumulated in studies of other TSE disorders contribute to better understanding of the documented kuru phenomena.

Mutational spectrum of the CHAC gene in patients with chorea-acanthocytosis.

Chorea-acanthocytosis (ChAc) is an autosomal recessive neurological disorder whose characteristic features include hyperkinetic movements and abnormal red blood cell morphology. Mutations in the CHAC gene on 9q21 were recently found to cause chorea-acanthocytosis. CHAC encodes a large, novel protein with a yeast homologue implicated in protein sorting. In this study, all 73 exons plus flanking intronic sequence in CHAC were screened for mutations by denaturing high-performance liquid chromatography in 43 probands with ChAc. We identified 57 different mutations, 54 of which have not previously been reported, in 39 probands. The novel mutations comprise 15 nonsense, 22 insertion/deletion, 15 splice-site and two missense mutations and are distributed throughout the CHAC gene. Three mutations were found in multiple families within this or our previous study. The preponderance of mutations that are predicted to cause absence of gene product is consistent with the recessive inheritance of this disease. The high proportion of splice-site mutations found is probably a reflection of the large number of exons that comprise the CHAC gene. The CHAC protein product, chorein, appears to have a certain tolerance to amino-acid substitutions since only two out of nine substitutions described here appear to be pathogenic.

Molecular genetic studies of Creutzfeldt-Jakob disease.

Genetic study of over 200 cases of Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker disease (GSS), fatal familial insomnia (FFI), and kuru have brought a reliable body of evidence that the familial forms of CJD and all known cases of GSS and FFI are linked to germline mutations in the coding region of the PRNP gene on chromosome 20, either point substitutions or expansion of the number of repeat units. No pathogenic mutations have so far been found in sporadic or infectious forms of CJD, although there are features of genetic predisposition in iatrogenic CJD and kuru. In FFI and familial CJD, clinically and pathologically distinct syndromes that are both linked to the 178Asp-->Asn substitution, phenotypic expression is dependent on a polymorphism at codon 129. Synthetic peptides homologous to several regions of PrP spontaneously form insoluble amyloid fibrils with unique morphological characteristics and polymerization tendencies. Peptides homologous to mutated regions of PrP exhibit enhanced fibrilogenic properties and, if mixed with the wild-type peptide, produce even more abundant and larger fibrous aggregates. A similar process in vivo may lead to amyloid accumulation and disease, and transmission of "baby fibrils" may induce disease in other hosts.

A novel mechanism of phenotypic heterogeneity demonstrated by the effect of a polymorphism on a pathogenic mutation in the PRNP (prion protein gene).

Fatal familial insomnia (FFI) is a subacute dementing illness originally described in 1986. The phenotypic characteristics of this disease include progressive untreatable insomnia, dysautonomia, endocrine and motor disorders, preferential hypometabolism in the thalamus as determined by PET scanning, and selective thalamic atrophy. These characteristics readily distinguish FFI from other previously described neurodegenerative conditions. Recently, FFI was shown to be linked to a mutation in the prion protein gene (PRNP) at codon 178, which results in the substitution of asparagine for aspartic acid. As such, FFI represents the most recent addition to the growing family of prion protein-related diseases. The mutation that results in FFI had previously been linked to a subtype of familial Creutzfeld-Jakob disease (178Asn CJD). The genotypic basis for the difference between FFI and 178AsnCJD lies in a polymorphism at codon 129 of the mutant prion protein gene: 129Met 178Asn results in FFI, 129Val 178Asn in CJD. The finding that the combination of a polymorphism and a single pathogenic mutation result in two distinct conditions represents a significant advance in our understanding of phenotypic variability.

Spinocerebellar ataxia type 1 in China: molecular analysis and genotype-phenotype correlation in 5 families.

BACKGROUND: Twelve genetic types of autosomal dominant hereditary ataxia have been recently identified and the genes responsible for most of them cloned. Molecular identification of the type of ataxia is important to determine the disease prevalence and its natural history in various populations. OBJECTIVES: To perform molecular analysis of 75 Chinese families affected with spinocerebellar ataxia (SCA) and to evaluate the spectrum of mutations in these genes and the correlation between genotypes and phenotypes in Chinese patients. SETTING: Neurogenetics Unit, China-Japan Friendship Hospital, Beijing, China. METHODS: One hundred nine patients from 75 kindreds diagnosed as having autosomal dominant SCA, 16 patients with sporadic SCA or spastic paraplegia, 280 control chromosomes of the Chinese population, and 120 control chromosomes of the Sakha population were selected for this study. We conducted detailed mutational analysis by direct sequencing of polymerase chain reaction products amplified from genomic DNA. RESULTS: Spinocerebellar ataxia type 1 (SCA1) was identified in 5 families with 12 studied patients. All affected family members were heterozygous for a CAG repeat expansion in the SCA1 gene containing 51 to 64 trinucleotide repeats. Normal alleles had 26 to 35 repeats. Spinocerebellar ataxia type 1 accounted for 7% of the studied Chinese families with ataxia. In addition, we determined the frequency of a single vs double CAT interruption in 120 control chromosomes of the Siberian Sakha population, which has the highest known prevalence of SCA1, and compared this with 280 control chromosomes from the Chinese populations. The results show that 64.7% of the Siberian normal alleles contain a single CAT interruption, whereas 92% of the Chinese had more than 1 interruption. CONCLUSIONS: Spinocerebellar ataxia type 1 is responsible for 7% of affected families in the Chinese population. A correlation between the prevalence of SCA1 and the number of CAT interruptions in the trinucleotide chain suggests that a CAT-to-CAG substitution may have been the initial event contributing to the generation of expanded alleles and influencing relative prevalence of SCA1.

A three-sister sibship of Gerstmann-Sträussler-Scheinker disease with a CJD phenotype.

OBJECTIVE: To describe a rare phenotypic variant of P102L Gerstmann-Sträussler-Scheinker disease (GSS). BACKGROUND: Classic GSS is characterized by an early age at onset, prominent cerebellar signs with a slowly evolving dementia, and a neuropathology including multifocal PrP-positive plaques and variable but usually modest spongiform change. METHODS: Clinical, neuropathologic, immunohistochemical, and molecular genetic analysis of three sisters in a Hungarian family was performed. RESULTS: The clinical course of all three sisters was indistinguishable from sporadic Creutzfeldt-Jakob disease (CJD). Neuropathologic examination revealed spongiform changes, PrP (prion)-positive unicentric "kuru" or multicentric plaques, and abundant beta-A4-positive senile plaques. Molecular genetic analysis of the PRNP gene showed the heterozygous codon P102L mutation of classic GSS, with the methionine encoding allele of a heterozygous codon 129 coupled to the mutant 102 allele. CONCLUSION: The authors report the second recorded example of a sporadic CJD phenotype occurring in association with the P102L GSS genotype, and the first instance in which the phenotype was the rule rather than the exception, or was associated with prominent beta-A4 plaque formation.

Olivopontocerebellar atrophy in a large Iakut kinship in eastern Siberia.

One-hundred cases of olivopontocerebellar atrophy, type 1, were found and studied in the Iakut population of Eastern Siberia. The disease followed a slowly progressive course of cerebellar insufficiency caused by degeneration in the cerebellar cortex, nuclei pontis, and inferior oliva. The disorder shows an autosomal dominant pattern of inheritance with a lower penetrance in females. The disease spread from a small region in the Aldan valley 200 to 300 years ago.

Inherited prion encephalopathy associated with the novel PRNP H187R mutation: a clinical study.

OBJECTIVE: To describe a variant of prion encephalopathy associated with the recently identified H187R mutation in the prion protein (PRNP) gene. METHODS: The authors studied a multigenerational American family with nine affected individuals. Clinical examination included imaging, EEG, and CSF analysis with 14-3-3 protein testing. Histopathology was characterized by examination of a brain biopsy from an H187R mutation-positive patient. RESULTS: The disease in this family is caused by the PRNP H187R mutation and characterized by autosomal dominant inheritance, median age at disease onset of 42 years (range 33 to 50 years), and median duration of illness of 12 years (range 8 to 19 years). Clinical signs include progressive dementia, ataxia, myoclonus, and seizures. Histopathologic features consist of distinctive "curly" prion protein deposits with a strictly laminar distribution in the cerebral cortex and minimal astrogliosis in the absence of amyloid plaques or spongiosis. CONCLUSION: A variant of prion encephalopathy associated with the novel H187R mutation in the PRNP gene displays distinctive clinical and immunostaining characteristics that further expand the boundaries of human prion disease.

A new (two-repeat) octapeptide coding insert mutation in Creutzfeldt-Jakob disease.

We report a family in which the proband died of clinically typical, neuropathologically verified Creutzfeldt-Jakob disease; her still-living mother suffers from a progressive dementia of many years' duration, and her maternal grandfather died after a similar illness. The proband, her mother, and two of three young first-degree relatives all have an identical insert mutation in the PRNP gene consisting of a twice-repeated 24-nucleotide sequence in the region between codons 51 and 91.

Mutations in American families with spinocerebellar ataxia (SCA) type 3: SCA3 is allelic to Machado-Joseph disease.

We identified an expansion of the CAG trinucleotide repeat in the coding region of the Machado-Joseph disease gene in 7 of 24 American families diagnosed with autosomal dominant ataxia. All affected individuals were heterozygous for an expanded allele that ranged from 67 to more than 200 CAG repeats, whereas the normal allele had 14 to 33 repeats. In contrast to the Azorean-Portuguese origins of Machado-Joseph disease, the two largest American families were of German and Dutch-African descent. Clinical, pathologic, and genetic evaluations suggest that American families with spinocerebellar ataxia type 3 differ from those with Machado-Joseph disease by their ethnic origins, predominant spinopontine atrophy, lack of dystonic features, and larger CAG repeat expansion.

Iatrogenic Creutzfeldt-Jakob disease: an example of the interplay between ancient genes and modern medicine.

We tested DNA from 15 centrally infected cases of iatrogenic Creutzfeldt-Jakob disease (CJD) (dura mater or corneal homografts and stereotactic EEG electrodes), 11 peripherally infected cases (native human growth hormone or gonadotrophin), and 110 control individuals for the presence of mutations in the chromosome 20 amyloid gene. No patient or control had any of the known pathogenic point or insert mutations found in familial disease, but allelic homozygosity at polymorphic codon 129 was present in all but two (92%) of the 26 patients, compared with 54 (50%) of the 110 controls (p < 0.001). Pooled data from all identified and tested cases of iatrogenic disease yielded a worldwide total of 56 patients, of whom all but four were homozygous at codon 129 (p < 0.001). These findings support the thesis that homozygosity at codon 129 enhances susceptibility to iatrogenic infections of both central and peripheral origin, with evident implications for the population of dura mater homograft and pituitary hormone recipients whose lives have been complicated by the possibility of exposure to the infectious agent of CJD.

Familial Creutzfeldt-Jakob disease with a five-repeat octapeptide insert mutation.

We report a familial form of Creutzfeldt-Jakob disease, associated with a unique insert mutation of the PRNP gene in an American family of Ukrainian origin. Ten family members exhibited early age at onset and long-duration illnesses characterized primarily by personality changes, cognitive impairment, and spasticity. The proband, presenting at age 42 years, exhibited a fairly stable, nonprogressive course over 7 years, followed by precipitous decline and death in the eighth year. Other affected family members exhibited marked clinical heterogeneity. Each tested affected member had an insert mutation consisting of five extra octapeptide repeats between codons 51 and 91 of the PRNP gene on chromosome 20. Examination of two autopsy cases showed classic spongiform change, neuronal loss and astrocytosis in one case, and minimal pathologic abnormality in the other case. This report documents a new insert mutation of the PRNP gene, and confirms the early age of onset, characteristically prolonged clinical course, and clinical and pathologic heterogeneity seen in such mutations.

Fatal insomnia in a case of familial Creutzfeldt-Jakob disease with the codon 200(Lys) mutation.

Fatal familial insomnia (FFI) has been exclusively associated with a pathogenic mutation at codon 178 in the PRNP gene coupled with methionine (Met) at codon 129. We now describe a subject with familial Creutzfeldt-Jakob disease, heterozygous for the pathogenic lysine (Lys) mutation at codon 200 and homozygous for Met at codon 129 of the PRNP gene, who was affected by severe insomnia. At autopsy the patient had significant involvement of the thalamus, as previously described in subjects affected by FFI with the codon 178 mutation. This case demonstrates the wide variability of the clinical expressions in patients with the codon 200 mutation, that may include insomnia and thalamic pathology.

Creutzfeldt-Jakob disease in a husband and wife.

A 53-year-old man died of sporadic Creutzfeldt-Jakob disease (CJD) after a 1.5-year clinical course. Four and a half years later, his then 55-year-old widow died from CJD after a 1-month illness. Both patients had typical clinical and neuropathologic features of the disease, and pathognomonic proteinase-resistant amyloid protein ("prion" protein, or PrP) was present in both brains. Neither patient had a family history of neurologic disease, and molecular genetic analysis of their PrP genes was normal. No medical, surgical, or dietary antecedent of CJD was identified; therefore, we are left with the unanswerable alternatives of human-to-human transmission or the chance occurrence of sporadic CJD in a husband and wife.