Sigrid Jusélius Foundation, Jane and Aatos Erkko Foundation, Molecular Medicine Institute of Finland, University of Helsinki, Helsinki University Central Hospital, Academy of Finland, Novo Nordisk, Arvo and Lea Ylppö Foundation.

BackgroundLeigh syndrome is a progressive neurodegenerative disorder, associated with primary or secondary dysfunction of the mitochondrial oxidative phosphorylation. Despite the fact that Leigh syndrome is the most common phenotype of mitochondrial disorders in children, longitudinal natural history data is missing. This study was undertaken to assess the phenotypic and genotypic spectrum of patients with Leigh syndrome, characterise the clinical course and identify predictors of survival in a large cohort of patients.MethodsThis is a retrospective study of patients with Leigh syndrome that have been followed at eight centers specialising in mitochondrial diseases in Europe; Gothenburg, Rotterdam, Helsinki, Copenhagen, Stockholm, Brussels, Bergen and Oulu.ResultsA total of 130 patients were included (78 males; 52 females), of whom 77 patients had identified pathogenic mutations. The median age of disease onset was 7 months, with 80.8% of patients presenting by the age of 2 years. The most common clinical features were abnormal motor findings, followed by abnormal ocular findings. Epileptic seizures were reported in 40% of patients. Approximately 44% of patients experienced acute exacerbations requiring hospitalisation during the previous year, mainly due to infections. The presence of pathological signs at birth and a history of epileptic seizures were associated with higher occurrence of acute exacerbations and/or relapses. Increased lactate in the cerebrospinal fluid was significantly correlated to a more severe disease course, characterised by early onset before 6 months of age, acute exacerbations and/or relapses, as well as brainstem involvement. 39% of patients had died by the age of 21 years, at a median age of 2.4 years. Disease onset before 6 months of age, failure to thrive, brainstem lesions on neuroimaging and intensive care treatment were significantly associated with poorer survival.ConclusionsThis is a multicenter study performed in a large cohort of patients with Leigh syndrome. Our data help define the natural history of Leigh syndrome and identify novel predictors of disease severity and long-term prognosis.

While data on the health-related quality of life (HRQOL) of adults are accumulating, very little is known about the HRQOL--and especially the perceived HRQOL--of children. In our study we introduced a 16-dimensional, generic self-assessment measure of HRQOL (16D) for early adolescents, and demonstrated its use with four populations of children aged 12-15: (1) 239 normal schoolchildren, (2) patients waiting for organ transplantation (n = 5), (3) patients with genetic skeletal dysplasias (n = 19), and (4) patients with epilepsy (n = 32). The HRQOL profiles of the patients differed significantly according to the diagnosis, giving support to its construct validity. The reliability of the measure was high: its repeatability coefficient was 91%. The quality of life ratings of the healthy boys and their parents differed on the dimensions of distress, vitality, speech, mental function, and discomfort and symptoms (p < 0.05). In addition, there were significant differences in the health-related valuations between the girls, boys and their parents. We conclude that the assessment of quality of life of adolescents should be based on data collected from the adolescents themselves. Further, the 16D is so far the only generic HRQOL measure designed specifically for this purpose. It is capable of differentiating the HRQOL of healthy adolescents as well as patients with various diagnoses. Our experience also indicates that it is easy to use, yet it seems comprehensive, reliable, and valid.