Mitochondrial Diseases in Childhood

Clinical, imaging, biochemical and molecular features in Leigh syndrome: a study from the Italian network of mitochondrial diseases

BACKGROUND

Leigh syndrome (LS) is a progressive neurodegenerative disorder associated with primary or secondary dysfunction of mitochondrial oxidative phosphorylation and is the most common mitochondrial disease in childhood. Numerous reports on the biochemical and molecular profiles of LS have been published, but there are limited studies on genetically confirmed large series. We reviewed the clinical, imaging, biochemical and molecular data of 122 patients with a diagnosis of LS collected in the Italian Collaborative Network of Mitochondrial Diseases database.

RESULTS

Clinical picture was characterized by early onset of several neurological signs dominated by central nervous system involvement associated with both supra- and sub-tentorial grey matter at MRI in the majority of cases. Extraneurological organ involvement is less frequent in LS than expected for a mitochondrial disorder. Complex I and IV deficiencies were the most common biochemical diagnoses, mostly associated with mutations in SURF1 or mitochondrial-DNA genes encoding complex I subunits. Our data showed SURF1 as the genotype with the most unfavorable prognosis, differently from other cohorts reported to date.

CONCLUSION

We report on a large genetically defined LS cohort, adding new data on phenotype-genotype correlation, prognostic factors and possible suggestions to diagnostic workup.

Central precocious puberty may be a manifestation of endocrine dysfunction in pediatric patients with mitochondrial disease

We retrospectively reviewed the data of 140 female pediatric patients with rare mitochondrial diseases (MDs) confirmed using muscle biopsy. We evaluated patients who were diagnosed with central precocious puberty (PP) with early pubertal development to determine whether PP is a clinical manifestation of MDs. We also examined the clinical, auxiological, laboratory, and radiological parameters after 1 year of gonadotropin-releasing hormone treatment for central PP. Among the 140 girls with MDs, 29 had early pubertal development and underwent endocrine evaluation. Ten (7.1%) patients were diagnosed with central PP; the prevalence of central PP was higher than was that previously thought. Patients with central PP exhibited bone age advancement over 1 year and increased sex hormone levels despite their young age at diagnosis. Serum estradiol levels were significantly higher in younger patients than in older patients (P = 0.004). Patients with central PP treated with gonadotropin-releasing hormone had favorable outcomes, and their pubertal development was suppressed for 1 year.Conclusion: Central PP may be a manifestation of endocrine dysfunction in young girls with MDs. What is Known: • The general characteristics of mitochondrial diseases include developmental delays and retarded growth. • Precocious puberty has rarely been suggested as a clinical manifestation of mitochondrial diseases. What is New: • Among the 140 girls with mitochondrial diseases, 10 (7.1%) were diagnosed with central precocious puberty. • Serum estradiol levels were significantly higher in younger patients than in older patients.

The Newcastle Pediatric Mitochondrial Disease Scale: translation and cultural adaptation for use in Brazil

ABSTRACT Objective The aim of this study was to translate and adapt the Newcastle Paediatric Mitochondrial Disease Scale (NPMDS) to Portuguese for use in Brazil. Methods The scale was applied in 20 pediatric patients with mitochondrial disease, in three groups: myopathy (n = 4); Leigh syndrome (n = 8); and encephalomyopathy (n = 8). Scores were obtained for the various dimensions of the NPMDS, and comparisons were drawn between the groups. Results There was a statistically significant difference between the myopathy group and the Leigh syndrome group (p = 0.0085), as well as between the myopathy and encephalomyopathy groups (p = 0.01). Conclusions The translation of the NPMDS, and its adaptation to the socioeconomic and cultural conditions in Brazil, make the NPMDS score useful as an additional parameter in the evaluation and monitoring of pediatric patients with MD in Brazil.