Leigh syndrome caused by mitochondrial DNA-maintenance defects revealed by whole exome sequencing.

Leigh syndrome represents a complex inherited neurometabolic and neurodegenerative disorder associated with different clinical, genetic and neuroimaging findings in the context of bilateral symmetrical lesions involving the brainstem and basal ganglia. Heterogeneous neurological manifestations such as spasticity, cerebellar ataxia, dystonia, choreoathetosis and parkinsonism are associated with multisystemic and ophthalmological abnormalities due to >75 different monogenic causes. Here, we describe the clinical and genetic features of a Brazilian cohort of patients with Leigh Syndrome in which muscle biopsy analysis showed mitochondrial DNA defects and determine the utility of whole exome sequencing for a final genetic diagnostic in this cohort.

Leukodystrophy with disorders of sex development due to WT1 mutations.

BACKGROUND: Hypomyelinating leukodystrophies represent an expanding group of neurogenetic disorders characterized primarily by central nervous system hypomyelination and variable neurological and non-neurological involvement. Hypomyelinating disorders have been rarely associated with gonadal dysfunction, being mainly represented by hypogonadotrophic hypogonadism in 4H syndrome. WT1 gene-associated disorders are classically associated with complex phenotypes including early carcinogenic risk for gonadoblastoma and Wilms' tumor, chronic renal failure, nephrotic syndrome and sex developmental disorders in intersex disorders and ambiguous genitalia. METHODS: The authors describe three non-related Brazilian patients with hypomyelinating leukodystrophy associated with complex neurological and systemic dysfunction with WT1 gene mutations. RESULTS: All described patients presented with similar neuroimaging features including thin corpus callosum, mild to moderate cerebellar atrophy and diffuse periventricular and profound hypomyelinating leukodystrophy involving supratentorial white matter with classical compromise linked to inherited non-somatic WT1 gene mutations in a similar pattern to Denys-Drash syndrome, including nephrotic syndrome with different glomerular disease, chronic renal failure, intersex disorder with ambiguous genitalia, and early occurrence of specific tumors, such as Wilms' tumor and gonadoblastoma. CONCLUSIONS: Clinicians must include WT1 gene mutations in the differential diagnosis of hypomyelinating leukodystrophy with nephrotic syndrome, chronic renal failure, ambiguous genitalia or sex developmental disorders.

New genetic causes for complex hereditary spastic paraplegia.

INTRODUCTION: Hereditary Spastic Paraplegia (HSP) represents a complex and heterogeneous group of rare neurodegenerative disorders that share a common clinical feature of weakness and lower limb spasticity that can occur alone or in combination with a constellation of other neurological or systemic signs and symptoms. Although the core clinical feature of weakness and lower limb spasticity is virtually universal, the genetic heterogeneity is almost uncountable with more than 70 genetic forms described so far. We performed review of medical records from twenty-one patients from seventeen Brazilian families with complex phenotype of HSP. All cases have previously negative mutations in SPG11/KIAA1840 and SPG7 gene and were evaluated by whole-exome sequencing. An extensive description of systemic and neurological signs has been described. RESULTS: Whole-exome sequencing was unremarkable in eight patients and established a definite genetic diagnosis in thirteen patients of twelve non-related families. Mutations were found in genes previously implicated in other neurodegenerative disorders such as Amyotrophic Lateral Sclerosis, Hereditary Neuropathy, Spastic Ataxias, Neurodegeneration with Brain Iron Accumulation, Glycogen Metabolism, Congenital Lipodystrophy and aminoacyl-tRNA synthetases disorders. CONCLUSIONS: We report thirteen new genetically-proven cases of complex HSP, expanding the clinical spectrum of presentations of HSP, providing new pathophysiological mechanisms and disclosing new potential therapeutic targets.