FERNANDO KOK
Projetos de Pesquisa
Unidades Organizacionais
Departamento de Neurologia, Faculdade de Medicina - Docente
LIM/45 - Laboratório de Fisiopatologia Neurocirúrgica, Hospital das Clínicas, Faculdade de Medicina
LIM/15 - Laboratório de Investigação em Neurologia, Hospital das Clínicas, Faculdade de Medicina
LIM/45 - Laboratório de Fisiopatologia Neurocirúrgica, Hospital das Clínicas, Faculdade de Medicina
LIM/15 - Laboratório de Investigação em Neurologia, Hospital das Clínicas, Faculdade de Medicina
13 resultados
Resultados de Busca
Agora exibindo 1 - 10 de 13
- Clinical and genetic characterization of leukoencephalopathies in adults(2017) LYNCH, David S.; PAIVA, Anderson Rodrigues Brandao de; ZHANG, Wei Jia; BUGIARDINI, Enrico; FREUA, Fernando; LUCATO, Leandro Tavares; MACEDO-SOUZA, Lucia Ines; LAKSHMANAN, Rahul; KINSELLA, Justin A.; MERWICK, Aine; ROSSOR, Alexander M.; BAJAJ, Nin; HERRON, Brian; MCMONAGLE, Paul; MORRISON, Patrick J.; HUGHES, Deborah; PITTMAN, Alan; LAURA, Matilde; REILLY, Mary M.; WARREN, Jason D.; MUMMERY, Catherine J.; SCHOTT, Jonathan M.; ADAMS, Matthew; FOX, Nick C.; MURPHY, Elaine; DAVAGNANAM, Indran; KOK, Fernando; CHATAWAY, Jeremy; HOULDEN, HenryLeukodystrophies and genetic leukoencephalopathies are a rare group of disorders leading to progressive degeneration of cerebral white matter. They are associated with a spectrum of clinical phenotypes dominated by dementia, psychiatric changes, movement disorders and upper motor neuron signs. Mutations in at least 60 genes can lead to leukoencephalopathy with often overlapping clinical and radiological presentations. For these reasons, patients with genetic leukoencephalopathies often endure a long diagnostic odyssey before receiving a definitive diagnosis or may receive no diagnosis at all. In this study, we used focused and whole exome sequencing to evaluate a cohort of undiagnosed adult patients referred to a specialist leukoencephalopathy service. In total, 100 patients were evaluated using focused exome sequencing of 6100 genes. We detected pathogenic or likely pathogenic variants in 26 cases. The most frequently mutated genes were NOTCH3, EIF2B5, AARS2 and CSF1R. We then carried out whole exome sequencing on the remaining negative cases including four family trios, but could not identify any further potentially disease-causing mutations, confirming the equivalence of focused and whole exome sequencing in the diagnosis of genetic leukoencephalopathies. Here we provide an overview of the clinical and genetic features of these disorders in adults.
- Subacute Partially Reversible Leukoencephalopathy Expands the Aicardi-Goutieres Syndrome Phenotype(2023) BARCELOS, Isabella Peixoto de; BUENO, Clarissa; GODOY, Luis Filipe S.; PESSOA, Andre; COSTA, Larissa A.; MONTI, Fernanda C.; SOUZA-CABRAL, Katiane; LISTIK, Clarice; CASTRO, Diego; DELLA-RIPA, Bruno; FREUA, Fernando; PIRES, Lais C.; KRUGER, Lia T.; GHERPELLI, Jose Luiz D.; PIAZZON, Flavia B.; MONTEIRO, Fabiola P.; LUCATO, Leandro T.; KOK, FernandoObjective: To report a series of atypical presentations of Aicardi-Goutieres syndrome. Methods: Clinical, neuroimaging, and genetic data. Results: We report a series of six unrelated patients (five males) with a subacute loss of developmental milestones, pyramidal signs, and regression of communication abilities, with onset at ages ranging from 7 to 20 months, reaching a nadir after 4 to 24 weeks. A remarkable improvement of lost abilities occurred in the follow-up, and they remained with residual spasticity and dysarthria but preserved cognitive function. Immunization or febrile illness occurred before disease onset in all patients. CSF was normal in two patients, and in four, borderline or mild lymphocytosis was present. A brain CT scan disclosed a subtle basal ganglia calcification in one of six patients. Brain MRI showed asymmetric signal abnormalities of white matter with centrum semi-ovale involvement in five patients and a diffuse white matter abnormality with contrast enhancement in one. Four patients were diagnosed and treated for acute demyelinating encephalomyelitis (ADEM). Brain imaging was markedly improved with one year or more of follow-up (average of 7 years), but patients remained with residual spasticity and dysarthria without cognitive impairment. Demyelination relapse occurred in a single patient four years after the first event. Whole-exome sequencing (WES) was performed in all patients: four of them disclosed biallelic pathogenic variants in RNASEH2B (three homozygous p.Ala177Thr and one compound heterozygous p.Ala177Thr/p.Gln58*) and in two of them the same homozygous deleterious variants in RNASEH2A (p.Ala249Val). Conclusions: This report expands the phenotype of AGS to include subacute developmental regression with partial clinical and neuroimaging improvement. Those clinical features might be misdiagnosed as ADEM.
- A novel GFAP mutation in a type II (late-onset) Alexander disease patient(2016) PAIVA, Anderson Rodrigues Brandao de; FREUA, Fernando; LUCATO, Leandro Tavares; PARMERA, Jacy; DORIA, Denise; NOBREGA, Paulo Ribeiro; OLAVIO, Thiago Rosa; MACEDO-SOUZA, Lucia Ines; KOK, Fernando
- Typical clinical and neuroimaging features in Sjogren-Larsson syndrome(2018) PAIVA, Anderson Rodrigues Brandao de; MELO, Uira Souto; FREUA, Fernando; DORIA, Denise; CABRAL, Katiane Sayao Souza; MACEDO-SOUZA, Lucia Ines; LUCATO, Leandro Tavares; KOK, Fernando
- A homozygous loss-of-function mutation in inositol monophosphatase 1 (IMPA1) causes severe intellectual disability(2016) FIGUEIREDO, T.; MELO, U. S.; PESSOA, A. L. S.; NOBREGA, P. R.; KITAJIMA, J. P.; RUSCH, H.; VAZ, F.; LUCATO, L. T.; ZATZ, M.; KOK, F.; SANTOS, S.The genetic basis of intellectual disability (ID) is extremely heterogeneous and relatively little is known about the role of autosomal recessive traits. In a field study performed in a highly inbred area of Northeastern Brazil, we identified and investigated a large consanguineous family with nine adult members affected by severe ID associated with disruptive behavior. The Genome-Wide Human SNP Array 6.0 microarray was used to determine regions of homozygosity by descent from three affected and one normal family member. Whole-exome sequencing (WES) was performed in one affected patient using the Nextera Rapid-Capture Exome kit and Illumina HiSeq2500 system to identify the causative mutation. Potentially deleterious variants detected in regions of homozygosity by descent and not present in either 59 723 unrelated individuals from the Exome Aggregation Consortium (Browser) or 1484 Brazilians were subject to further scrutiny and segregation analysis by Sanger sequencing. Homozygosity-by-descent analysis disclosed a 20.7-Mb candidate region at 8q12.3-q21.2 (lod score: 3.11). WES identified a homozygous deleterious variant in inositol monophosphatase 1 (IMPA1) (NM_005536), consisting of a 5-bp duplication (c.489_493dupGGGCT; chr8: 82,583,247; GRCh37/hg19) leading to a frameshift and a premature stop codon (p.Ser165Trpfs*10) that cosegregated with the disease in 26 genotyped family members. The IMPA1 gene product is responsible for the final step of biotransformation of inositol triphosphate and diacylglycerol, two second messengers. Despite its many physiological functions, no clinical phenotype has been assigned to this gene dysfunction to date. Additionally, IMPA1 is the main target of lithium, a drug that is at the forefront of treatment for bipolar disorder.
- Chronic stage of Marchiafava-Bignami disease(2015) LUCATO, Leandro Tavares; FREUA, Fernando; KOK, Fernando
- Imaging of adult leukodystrophies(2014) LEITE, Claudia Costa; LUCATO, Leandro Tavares; SANTOS, Germano Titoneli; KOK, Fernando; BRANDAO, Anderson Rodrigues; CASTILLO, MauricioLeukodystrophies are genetically determined white matter disorders. Even though leukodystrophies essentially affect children in early infancy and childhood, these disorders may affect adults. In adults, leukodystrophies may present a distinct clinical and imaging presentation other than those found in childhood. Clinical awareness of late-onset leukodystrophies should be increased as new therapies emerge. MRI is a useful tool to evaluate white matter disorders and some characteristics findings can help the diagnosis of leukodystrophies. This review article briefly describes the imaging characteristics of the most common adult leukodystrophies.
- Arginase 1 deficiency presenting as complicated hereditary spastic paraplegia(2022) FREUA, Fernando; ALMEIDA, Mariana Espindola de Castro; NOBREGA, Paulo Ribeiro; PAIVA, Anderson Rodrigues Brandao de; DELLA-RIPA, Bruno; CUNHA, Paulina; MACEDO-SOUZA, Lucia Ines; BUENO, Clarissa; LYNCH, David S. S.; HOULDEN, Henry; LUCATO, Leandro Tavares; KOK, FernandoArgininemia 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 seven patients with arginase 1 deficiency from six different families, all with an initial diagnosis of complicated HSP. We evaluated the clinical data of seven patients belonging to six independent families who were diagnosed with hyperargininemia in a neurogenetics outpatient clinic. 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, magnetic resonance imaging (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. A clinical diagnosis of early-onset complicated hereditary spastic paraplegia was made in all patients. Two patients were initially suspected of having SPG11 because of 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 among the complicated HSPs.
- Adult Leukodystrophies: A Step-by-Step Diagnostic Approach(2019) RESENDE, Lucas Lopes; PAIVA, Anderson Rodrigues Brandao de; KOK, Fernando; LEITE, Claudia da Costa; LUCATO, Leandro TavaresLeukodystrophies usually affect children, but in the last several decades, many instances of adult leukodystrophies have been reported in the medical literature. Because the clinical manifestation of these diseases can be nonspecific, MRI can help with establishing a diagnosis. A step-by-step approach to assist in the diagnosis of adult leukodystrophies is proposed in this article. The first step is to identify symmetric white matter involvement, which is more commonly observed in these patients. The next step is to fit the symmetric white matter involvement into one of the proposed patterns. However, a patient may present with more than one pattern of white matter involvement. Thus, the third step is to evaluate for five distinct characteristics-including enhancement, lesions with signal intensity similar to that of cerebrospinal fluid, susceptibility-weighted MRI signal intensity abnormalities, abnormal peaks at MR spectroscopy, and spinal cord involvement-to further narrow the differential diagnosis. (C) RSNA, 2019
- A novel complex neurological phenotype due to a homozygous mutation in FDX2(2018) GURGEL-GIANNETTI, Juliana; LYNCH, David S.; PAIVA, Anderson Rodrigues Brandao de; LUCATO, Leandro Tavares; YAMAMOTO, Guilherme; THOMSEN, Christer; BASU, Somsuvro; FREUA, Fernando; GIANNETTI, Alexandre Varella; ASSIS, Bruno Della Ripa de; RIBEIRO, Mara Dell Ospedale; BARCELOS, Isabella; SOUZA, Katiane Sayao; MONTI, Fernanda; MELO, Uira Souto; AMORIM, Simone; SILVA, Leonardo G. L.; MACEDO-SOUZA, Lucia Ines; VIANNA-MORGANTE, Angela M.; HIRANO, Michio; KNAAP, Marjo S. Van der; LILL, Roland; VAINZOF, Mariz; OLDFORS, Anders; HOULDEN, Henry; KOK, FernandoDefects in iron-sulphur [Fe-S] cluster biogenesis are increasingly recognized as causing neurological disease. Mutations in a number of genes that encode proteins involved in mitochondrial [Fe-S] protein assembly lead to complex neurological phenotypes. One class of proteins essential in the early cluster assembly are ferredoxins. FDX2 is ubiquitously expressed and is essential in the de novo formation of [2Fe-2S] clusters in humans. We describe and genetically define a novel complex neurological syndrome identified in two Brazilian families, with a novel homozygous mutation in FDX2. Patients were clinically evaluated, underwent MRI, nerve conduction studies, EMG and muscle biopsy. To define the genetic aetiology, a combination of homozygosity mapping and whole exome sequencing was performed. We identified six patients from two apparently unrelated families with autosomal recessive inheritance of a complex neurological phenotype involving optic atrophy and nystagmus developing by age 3, followed by myopathy and recurrent episodes of cramps, myalgia and muscle weakness in the first or second decade of life. Sensory-motor axonal neuropathy led to progressive distal weakness. MRI disclosed a reversible or partially reversible leukoencephalopathy. Muscle biopsy demonstrated an unusual pattern of regional succinate dehydrogenase and cytochrome c oxidase deficiency with iron accumulation. The phenotype was mapped in both families to the same homozygous missense mutation in FDX2 (c. 431C > T, p. P144L). The deleterious effect of the mutation was validated by real-time reverse transcription polymerase chain reaction and western blot analysis, which demonstrated normal expression of FDX2 mRNA but severely reduced expression of FDX2 protein in muscle tissue. This study describes a novel complex neurological phenotype with unusual MRI and muscle biopsy features, conclusively mapped to a mutation in FDX2, which encodes a ubiquitously expressed mitochondrial ferredoxin essential for early [Fe-S] cluster biogenesis.