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Introduction: Late infantile neuronal ceroid lipofuscinosis type 2 (CLN2), is a neurodegenerative autosomal recessive disease caused by TPP1 gene variants, with a spectrum of classic and atypical phenotypes. The aim of treatment is to slow functional decline as early as possible in an attempt to improve quality of life and survival. This study describes the clinical characteristics as well as the response to treatment with cerliponase alfa. Materials and methods: A retrospective study was conducted in five Latin-American countries, using clinical records from patients with CLN2. Clinical follow-up and treatment variables are described. A descriptive and bivariate statistical analysis was performed. Results: A total of 36 patients were observed (range of follow-up of 61-110 weeks post-treatment). At presentation, patients with the classic phenotype (n = 16) exhibited regression in language (90%), while seizures were the predominant symptom (87%) in patients with the atypical phenotype (n = 20). Median age of symptom onset and time to first specialized consultation was 3 (classical) and 7 (atypical) years, while the median time interval between onset of symptoms and treatment initiation was 4 years (classical) and 7.5 (atypical). The most frequent variant was c.827 A > T in 17/72 alleles, followed by c.622C > T in 6/72 alleles. All patients were treated with cerliponase alfa, and either remained functionally stable or had a loss of 1 point on the CLN2 scale, or up to 2 points on the Wells Cornel and Hamburg scales, when compared to pretreatment values. Discussion and conclusion: This study reports the largest number of patients with CLN2 currently on treatment with cerliponase alfa in the world. Data show a higher frequency of patients with atypical phenotypes and a high allelic proportion of intron variants in our region. There was evidence of long intervals until first specialized consultation, diagnosis, and enzyme replacement therapy. Follow-up after the initiation of cerliponase alfa showed slower progression or stabilization of the disease, associated with adequate clinical outcomes and stable functional scores. These improvements were consistent in both clinical phenotypes.
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BACKGROUND: Diagnostic trajectories for neurogenetic disorders frequently require the use of considerable time and resources, exposing patients and families to so-called "diagnostic odysseys". Previous studies have provided strong evidence for increased diagnostic and clinical utility of whole-exome sequencing in medical genetics. However, specific reports assessing its utility in a setting such as ours- a neurogeneticist led academic group serving in a low-income country-are rare. OBJECTIVES: To assess the diagnostic yield of WES in patients suspected of having a neurogenetic condition and explore the cost-effectiveness of its implementation in a research group located in an Argentinean public hospital. METHODS: This is a prospective study of the clinical utility of WES in a series of 40 consecutive patients selected from a Neurogenetic Clinic of a tertiary Hospital in Argentina. We evaluated patients retrospectively for previous diagnostic trajectories. Diagnostic yield, clinical impact on management and economic diagnostic burden were evaluated. RESULTS: We demonstrated the clinical utility of Whole Exome Sequencing in our patient cohort, obtaining a diagnostic yield of 40% (95% CI, 24.8%-55.2%) among a diverse group of neurological disorders. The average age at the time of WES was 23 (range 3-70). The mean time elapsed from symptom onset to WES was 11 years (range 3-42). The mean cost of the diagnostic workup prior to WES was USD 1646 (USD 1439 to 1853), which is 60% higher than WES cost in our center. CONCLUSIONS: WES for neurogenetics proved to be an effective, cost- and time-saving approach for the molecular diagnosis of this heterogeneous and complex group of patients.
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Análise Custo-Benefício , Sequenciamento do Exoma/economia , Testes Genéticos/economia , Sequenciamento de Nucleotídeos em Larga Escala/economia , Doenças do Sistema Nervoso/diagnóstico , Adolescente , Adulto , Idoso , Argentina , Criança , Pré-Escolar , Exoma , Feminino , Predisposição Genética para Doença , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Doenças do Sistema Nervoso/economia , Doenças do Sistema Nervoso/genética , Estudos Prospectivos , Sequenciamento do Exoma/métodos , Adulto JovemRESUMO
BACKGROUND: GenIO is a novel web-server, designed to assist clinical genomics researchers and medical doctors in the diagnostic process of rare genetic diseases. The tool identifies the most probable variants causing a rare disease, using the genomic and clinical information provided by a medical practitioner. Variants identified in a whole-genome, whole-exome or target sequencing studies are annotated, classified and filtered by clinical significance. Candidate genes associated with the patient's symptoms, suspected disease and complementary findings are identified to obtain a small manageable number of the most probable recessive and dominant candidate gene variants associated with the rare disease case. Additionally, following the American College of Medical Genetics and Genomics and the Association of Molecular Pathology (ACMG-AMP) guidelines and recommendations, all potentially pathogenic variants that might be contributing to disease and secondary findings are identified. RESULTS: A retrospective study was performed on 40 patients with a diagnostic rate of 40%. All the known genes that were previously considered as disease causing were correctly identified in the final inherit model output lists. In previously undiagnosed cases, we had no additional yield. CONCLUSION: This unique, intuitive and user-friendly tool to assists medical doctors in the clinical genomics diagnostic process is openly available at https://bioinformatics.ibioba-mpsp-conicet.gov.ar/GenIO/ .
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Doenças Raras/genética , Interface Usuário-Computador , Estudos de Associação Genética , Genótipo , Humanos , Internet , Fenótipo , Doenças Raras/patologiaRESUMO
Neuronal migration disorders are a clinically and genetically heterogeneous group of malformations of cortical development, frequently responsible for severe disability. Despite the increasing knowledge of the molecular mechanisms underlying this group of diseases, their genetic diagnosis remains unattainable in a high proportion of cases. Here, we present the results of 38 patients with lissencephaly, periventricular heterotopia and subcortical band heterotopia from Argentina. We performed Sanger and Next Generation Sequencing (NGS) of DCX, FLNA and ARX and searched for copy number variations by MLPA in PAFAH1B1, DCX, POMT1, and POMGNT1. Additionally, somatic mosaicism at 5% or higher was investigated by means of targeted high coverage NGS of DCX, ARX, and PAFAH1B1. Our approach had a diagnostic yield of 36%. Pathogenic or likely pathogenic variants were identified in 14 patients, including 10 germline (five novel) and 4 somatic mutations in FLNA, DCX, ARX and PAFAH1B1 genes. This study represents the largest series of patients comprehensively characterized in our population. Our findings reinforce the importance of somatic mutations in the pathophysiology and diagnosis of neuronal migration disorders and contribute to expand their phenotype-genotype correlations.
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Mutação em Linhagem Germinativa , Malformações do Desenvolvimento Cortical do Grupo II/genética , Estudos de Coortes , Variações do Número de Cópias de DNA , Feminino , Genótipo , Humanos , Masculino , Malformações do Desenvolvimento Cortical do Grupo II/diagnóstico , Fenótipo , Adulto JovemAssuntos
Ataxia/diagnóstico , Ataxia/genética , Cerebelo/metabolismo , Predisposição Genética para Doença , Mutação , Semântica , Ubiquitina-Proteína Ligases/genética , Adulto , Ataxia/fisiopatologia , Atrofia , Cerebelo/patologia , Cerebelo/fisiopatologia , Cognição , Estudos de Associação Genética , Humanos , Masculino , Atividade Motora , NeuroimagemRESUMO
As a whole neurogenetic diseases are a common group of neurological disorders. However, the recognitionand molecular diagnosis of these disorders is not always straightforward. Besides, there is a paucity of informationregarding the diagnostic yield that specialized neurogenetic clinics could obtain. We performed a prospective,observational, analytical study of the patients seen in a neurogenetic clinic at a tertiary medicalcentre to assess the diagnostic yield of a comprehensive diagnostic evaluation that included a personalizedclinical assessment along with traditional and next-generation sequencing diagnostic tests. We included a cohortof 387 patients from May 2008 to June 2014. For sub-group analysis we selected a sample of patientswhose main complaint was the presence of progressive ataxia, to whom we applied a systematic moleculardiagnostic algorithm. Overall, a diagnostic mutation was identified in 27·4% of our cohort. However, if weonly considered those patients where a molecular test could be performed, the success rate rises to 45%. Weobtained diagnostic yields of 23·5 and 57·5% in the global group of ataxic patients and in the subset of ataxicpatients with a positive family history, respectively. Thus, about a third of patients evaluated in a neurogeneticclinic could be successfully diagnosed.
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Sequenciamento de Nucleotídeos em Larga Escala/métodos , Doenças do Sistema Nervoso/diagnóstico , Doenças do Sistema Nervoso/genética , Medicina de Precisão/métodos , Adolescente , Adulto , Idoso , Argentina , Ataxia/diagnóstico , Ataxia/genética , Criança , Análise Mutacional de DNA , Saúde da Família , Feminino , Predisposição Genética para Doença/genética , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Estudos Prospectivos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Centros de Atenção Terciária , Adulto JovemRESUMO
We described a case of a patient with autosomal dominant progressive external ophthalmoplegia (PEO) who presented with the acute onset dysphagia, quadriparesis, ptosis and respiratory insufficiency following a cardiac procedure and mimicking a myasthenic crisis. A pathogenic mutation in the C10orf2 (PEO1) gene was confirmed. The unusual presentation of our patient contributes to expand the clinical phenotype of PEO1 mutations and reinforces the need to consider mitochondrial myopathy as differential diagnosis of myasthenia gravis even in the case of acute onset symptoms.
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Miastenia Gravis/diagnóstico , Oftalmoplegia Externa Progressiva Crônica/diagnóstico , DNA Helicases/genética , Diagnóstico Diferencial , Humanos , Masculino , Pessoa de Meia-Idade , Proteínas Mitocondriais/genética , Mutação , Oftalmoplegia Externa Progressiva Crônica/genéticaRESUMO
Huntington's disease (HD) is a neurodegenerative disorder of the central nervous system characterised by the presence of choreic abnormal movements, behavioural or psychiatric disturbances and dementia. Noteworthy, despite atypical motor symptoms other than chorea have been reported as initial presentation in some patients, a very few number of HD patients, presenting at onset mostly cerebellar dysfunction masquerading dominant spinocerebellar ataxias (SCA), were occasionally reported. We report the case of a 42-year-old man with a 5-year history of gait disturbance, dysarthria and cognitive impairment and familial antecedents of dementia and movement disorders. Initially the clinical picture suggested the diagnosis of a dominant SCA, but finally a diagnosis of HD was made based on the molecular evidence of abnormal 39 Cytosine-Adenine-Guanine (CAG) repeats in exon 1 of Huntingtin gene. The authors highlight the importance of suspecting HD in the aetiology of spinocerebellar ataxias when dementia is a prominent feature in the proband or their family.
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Doença de Huntington/diagnóstico , Ataxias Espinocerebelares/diagnóstico , Adulto , Diagnóstico Diferencial , Humanos , Doença de Huntington/genética , Imageamento por Ressonância Magnética , Masculino , LinhagemRESUMO
There seems to be a role for serotoninergic neuro-transmission in the pathophysiology of the epilepsies. Different groups have studied the role of regulatory variants in the SLC6A4 gene, which code for the central serotonin transporter, in the complex genetics of temporal lobe epilepsy (TLE) obtaining contradictory findings. Therefore, a systematic review and critical analysis of this topic seem to be timely. Published studies up to October 2011 of TLE and the SLC6A4 promoter and intron 2 variant number repeat polymorphisms (VNTR) were identified by searches of Medline, Scopus and ISI-Web of Sciences databases. Meta-analysis of TLE case-control data were performed to assess the association of SLC6A4 VNTRs with TLE susceptibility. Pooled odds ratios were estimated by means of a genetic-model-free approach. The quality of the included studies was assessed by a score. The studies included compared a total of 991 TLE cases and 1,202 controls. We did not find synthetic evidence of association between SLC6A4 promoter and intron 2 variants and the risk of TLE. However, the intron 2 VNTR seems to have opposite effects in different populations. In this meta-analysis our findings were inconclusive in order to associate any of the 5-HT receptor gene variants with the risk of TLE.