Arginase 1 deficiency presenting as complicated hereditary spastic paraplegia

INTRODUCTION: Argininemia or arginase deficiency is a metabolic disorder caused by pathogenic variants in ARG1 and consists of a variable association of progressive spastic paraplegia, intellectual disability, and seizures. Hereditary spastic paraplegia (HSP) is a group of inherited diseases whose main feature is a progressive gait disorder characterized by lower limb spasticity. This study presents 7 patients with arginase 1 deficiency from 6 different families, all with an initial diagnosis of complicated HSP. METHODS: We evaluated the clinical data of 7 patients belonging to six independent families who were diagnosed with hyperargininemia in a neurogenetics outpatient clinic. RESULTS: All patients had lower limb spasticity and six had global developmental delay. Five individuals had intellectual disability and two had epilepsy. Psychiatric abnormalities were seen in two patients. In two participants of this study, MRI disclosed thinning of the corpus callosum. Molecular diagnosis was made by whole exome sequencing. All variants were present in homozygosis; we identified two novel missense variants, one novel frameshift variant, and one previously published missense variant. DISCUSSION: Clinical diagnosis of early onset complicated hereditary spastic paraplegia was made in all patients. Two patients were initially suspected of having SPG11 due to thinning of the corpus callosum. As argininemia may present with a highly penetrant phenotype of spastic paraplegia associated with additional symptoms, this disease may represent a specific entity amongst the complicated HSPs

Clinical and molecular characterization of a large cohort of childhood onset hereditary spastic paraplegias

The present study aimed to characterize clinical and molecular data of a large cohort of subjects with childhood-onset hereditary spastic paraplegias (HSPs). A multicenter historical cohort was performed at five centers in Brazil, in which probands and affected relatives' data from consecutive families with childhood-onset HSP (onset < 12 years-old) were reviewed from 2011 to 2020. One hundred and six individuals (83 families) with suspicion of childhood-onset HSP were evaluated, being 68 (50 families) with solved genetic diagnosis, 6 (5 families) with candidate variants in HSP-related genes and 32 (28 families) with unsolved genetic diagnosis. The most common childhood-onset subtype was SPG4, 11/50 (22%) families with solved genetic diagnosis; followed by SPG3A, 8/50 (16%). Missense pathogenic variants in SPAST were found in 54.5% of probands, favoring the association of this type of variant to childhood-onset SPG4. Survival curves to major handicap and cross-sectional Spastic Paraplegia Rating Scale progressions confirmed the slow neurological deterioration in SPG4 and SPG3A. Most common complicating features and twenty variants not previously described in HSP-related genes were reported. These results are fundamental to understand the molecular and clinical epidemiology of childhood-onset HSP, which might help on differential diagnosis, patient care and guiding future collaborative trials for these rare diseases

Clinical and genetic investigation of hereditary spastic paraplegia

O presente estudo realizou análise retrospectiva e parcialmente prospectiva de pacientes com diagnóstico de paraplegia espástica hereditária que são acompanhados no ambulatório de Neurogenética (NCL6500) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. Apresenta como objetivo principal descrever os aspectos clínicos, genéticos, laboratoriais, de neuroimagem e eletrofisiológicos destes pacientes e como objetivo secundário visa identificar características no exame clínico, nos estudos laboratoriais e eletrofisiológicos e nas diferentes técnicas de neuroimagem, além de dados epidemiológicos, que contribuam para a definição etiológica, além de relacionar achados clínicos e laboratoriais com possíveis padrões genéticos. Os pacientes incluídos foram avaliados clinicamente por meio da versão brasileira da escala SPRS (Spastic Paraplegia Rating Scale) e também com avaliação cognitiva através do mini-exame do estado mental (quando aplicável) e submetidos a estudo de ressonância magnética de encéfalo e eletrofisológicos (quando aplicáveis), além da realização da investigação genética com técnicas diversas, inclusive por meio do sequenciamento completo do exoma. Entre os 70 sujeitos incluídos na pesquisa, o estudo genético foi conclusivo em 39 . Nos casos confirmados foi realizada a descrição clínica e sociodemográficas detalhada e realizado comparação entre os resultados por meio de análise estatística descritiva. Foi realizada ainda análise estatística inferencial que revelou relação entre achado de neuroimagem de corpo caloso afilado com gravidade da escala SPRS. Conclui-se por este estudo que a apresentação demográfica dos pacientes com paraplegia espástica hereditária é fenotípica e geneticamente variável, sendo o padrão autossômico recessivo o mais encontrado nesta amostra, com destaque para SPG11. Identificamos ainda casos habitualmente não classificados entre as paraplegias espásticas hereditárias, tais como a deficiência de arginase ou que representam uma expansão fenotípica, como a forma autossômica recessiva de paraplegia espástica associada a SQSTM1The present study performed a retrospective and partially prospective analysis of all patients diagnosed with hereditary spastic paraplegia followed in the Neurogenetics Outpatient Service (NCL6500) at Hospital das Clinicas, Faculdade de Medicina, Universidade de São Paulo. Its main objective is to describe the clinical, genetic, laboratorial, neuroimaging and electrophysiological aspects of these patients and as a secondary objective it aims to identify characteristics in the clinical examination, laboratorial and electrophysiological studies and in the different neurological imaging techniques, in addition to epidemiological data that contribute for the etiological definition, as well to relate clinical and laboratory findings with possible genetic patterns. Included patients were clinically evaluated using the SPRS (Spastic Paraplegia Rating Scale) Brazilian version and a cognitive assessment through the mini mental state exam (when applicable). Additionally brain magnetic resonance imaging and whenever applicable, electrophysiological studies were done. Different techniques for genetic analysis were performed, including whole exome sequencing. Of the 70 patients included in the survey, a conclusive genetic result was achieved in 39. In confirmed cases, a detailed clinical and sociodemographic description was performed and a comparison between the results was carried out through descriptive statistical analysis. Inferential statistical analysis was also carried out, which revealed a relationship between the neuroimaging finding of the thin corpus callosum and the severity of the SPRS scale. This study concludes that the demographic presentation of patients with hereditary spastic paraplegia is phenotypic and genetically variable, with the autosomal recessive pattern being the most common in the sample and the pathogenic variants in the SPG11 gene the most prevalent. We also identified cases not habitually classified as hereditary spastic paraplegia, as arginase deficiency and a phenotypic expansion, as SQSTSM1-related autosomal recessive spastic paraplegi