Thesis (DMed (Medicine. Internal Medicine))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Progressive Myoclonic Epilepsies (PME) are characterized by progressive neurological impairment with myoclonus, seizures and dementia. In contradistinction, Familial Adult Myoclonic Epilepsy (FAME) is characterized by a benign course with rare seizures and cortical tremor. Both conditions have neurophysiological features suggestive of a cortical origin for their myoclonus. This dissertation reports on a novel form of PME. Many of those who were affected had no or minimal progression of their illness, low seizure frequency and were cognitively intact, suggestive of non-progressive disorders linked to the FAME loci. The majority of patients had features of cortical myoclonus, with generalized spike and wave discharges on electroencephalography, enlarged evoked potentials, enhanced C reflexes, and evidence of cortical excitability with magnetic stimulation. However, there was evidence of cerebellar dysfunction both pathologically and on imaging. With regard to similar conditions, dentatorubral pallidoluysian atrophy and Unverricht-Lundborg syndrome were excluded by linkage analysis. Similarly, linkage was not present for either the FAME 1 or FAME 2 loci. This syndrome is both clinically and genetically novel, and has a nosology which is difficult to characterize, in which the condition appears to lie on the spectrum between FAME and PME. The dissociation between the pathological and radiological findings which suggest subcortical dysfunction, and the neurophysiological findings of cortical myoclonus is striking. Review of the literature associated with the neurophysiology of related conditions associated with PME and FAME suggests that: 1. The assumption that generalized forms of myoclonic disorders represent multifocal forms of focal cortical discharges is an oversimplification. 2. The dissociation between initial and later components of the evoked potential is less robust than is generally supposed, and that subcortical inputs may affect later components of the evoked potential. 3. In a high proportion of cases the latency from cortical spike discharge to myoclonic jerk obtained with jerk locked averaging is incompatible with a cortical origin for the spike discharge. 4. The proposal that myoclonus is a form of long latency reflex and that myoclonus represents a reflex arising from subclinical sensory input, is unproven. / AFRIKAANSE OPSOMMING: Progressiewe Miokloniese Epilepsie (PME) word gekenmerk deur progressiewe neurologiese agteruitgang met mioklonus, konvulsies en demensie. Daarenteen word Familiële Volwasse Miokloniese Epilepsie (FAME) gekenmerk deur 'n benigne verloop met ongereelde konvulsies en kortikale tremor. Beide entiteite het neurofisiologiese kenmerke suggestief van 'n kortikale oorsprong vir die mioklonus. Hierdie manuskrip beskryf 'n nuwe vorm van PME. Baie van die aangetaste persone toon geen of min agteruitgang van die siekte oor tyd nie, met 'n lae frekwensie van konvulsies en is kognitief intak, wat suggestief is van 'n nie-progressiewe siekte gekoppel aan die FAME loci. Die oorgrote meerderheid van pasiente het kenmerke van kortikale mioklonus gehad, met algemene spits en boog ontladings op elektroensefalografie, hoë amplitude ontlokte potensiale, versterkte C-reflekse, en tekens van kortikale eksiteerbaarheid met magnetiese stimulasie. Met neurobeelding en patologie was daar egter bewyse van serebellêre disfunksie. Soortgelyke toestande, naamlik dentatorubro-pallidoluysiese atrofie en Unverricht-Lundborg sindroom is uitgeskakel deur middel van koppelingsanalise. Koppeling met die FAME1 of FAME2 loci kon ook nie aangetoon word nie. Die sindroom is beide klinies sowel as geneties nuut en het 'n nosologie wat moeilik gekaraktiseer kan word. Dit wil voorkom of die siekte op 'n spektrum lê tussen FAME en PME. Die dissosiasie tussen die patologiese en radiologiese bevindinge, wat suggestief is van subkortikale disfunksie, en die neurofisiologiese bevindinge van kortikale mioklonus is opmerklik. ’n Oorsig van die literatuur in verband met die neurofisiologie van toestande geassosieer met PME en FAME suggesteer die volgende: 1. Die aanname dat algemene vorme van miokloniese toestande multifokale vorme van fokale kortikale ontladings verteenwoordig, is ’n oorvereenvoudiging. 2. Die dissosiasie tussen inisiële en latere komponente van die ontlokte potensiaal is minder robuust as wat algemeen aanvaar word, en subkortikale invoer mag latere komponente van die ontlokte potensiaal beïnvloed. 3. In ’n groot proporsie van gevalle is die latensie van kortikale spits ontlading tot miokloniese ruk, verkry deur “jerk locked averaging”, nie verenigbaar met met ’n kortikale oorsprong vir die spits ontlading nie. 4. Geen bewyse bestaan vir die teorie dat mioklonus ’n vorm van ’n lang latensie refleks is en dat mioklonus ’n refleks is wat ontstaan uit subkliniese sensoriese invoer nie.

A doença de Unverricht-Lundborg (DUL) é considerada uma doença rara, autossômica recessiva, sendo também denominada de Epilepsia Mioclônica Progressiva do tipo1 (emp1), causada por mutações no gene codificador (CSTB) da proteína cistatina B. A cistatina B é uma proteína essencial para a regulação dos processos fisiológicos do ser humano, e sua expressão reduzida parece ser a causa primária da EMP1. A doença em geral se inicia entre os seis e dezesseis anos, manifestando-se tanto como crises mioclônicas como por crises tônicoclônicas generalizadas. Trata-se de uma doença grave e limitante, cujo diagnóstico preciso é extremamente importante para as condutas apropriadas, incluindo aconselhamento genético. Este estudo tem como objetivo o estudo molecular e caracterização da expansão instável de repetição dodecamérica (CCCCGCCCCGCG) da região promotora 5\' não traduzida do gene CSTB entre pacientes com suspeita de EMP1 na população brasileira. No presente estudo, selecionamos 64 pacientes entre eles 54 casos índices do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto (HCFMRP-USP) com suspeita de EMP1. Os restantes 10 casos eram parentes dos casos índices. Os 54 pacientes foram seguidos no setor de Epilepsia com diagnostico clinico e eletrofisiológico de EMP1, e foram encaminhados para o setor de Neurogenética para diagnostico molecular. Destes 54 casos índices, apenas 5 foram diagnosticados através da biologia molecular com expansão dodecamera acima de 30 repetições, sugestivo de DUL. Espera-se, com este estudo, identificar a população de pacientes com EPM1 que tenham mutação no gene CSTB e com os resultados de este projeto possibilitar assim um melhor entendimento da etiopatogenia e proporcionar um diagnóstico preciso dos casos de DUL. / Unverricht-Lundborg disease (ULD) is considered a rare autosomal recessive disease, also known as Progressive Myoclonic Epilepsy Type 1 (EMP1), caused by mutations in the CSTB gene, which provides instructions for making a protein called Cystatin B. Such protein is essential for regulating a person\'s physiological processes, and its reduced expression seems to be the first cause of EMP1. Affected individuals usually begin showing signs and symptoms of the disorder between the ages of 6 and 16, which manifests both as myoclonus or as generalized tonic-clonic crises. It is a grave and limiting condition whose precise diagnosis is extremely important for appropriate conducts, including genetic counseling. This study has as a goal the molecular evaluation and characterization of the unstable expansion of the decametric repetition (CCCCGCCCCGCG) from the non-translated CSTB\'s 5\' gene promoter region among Brazilian patients with suspected EMP1. In this study, 64 patients were selected, among them 54 key figures from Hospital das Clínicas of Faculdade de Medicina de Ribeirão Preto (HCFMRP-USP) with suspected EMP1. The other 10 figures were related to the key figures. The 54 patients were followed in the Epilepsy sector with EMP1 clinical and electrophysiological diagnostics and were forwarded to the neurogenetics sector for a molecular diagnostic. From such 54 key figures, only 5 were diagnosed through molecular biology with decametric expansion above 30 repetitions, suggestive of ULD. This study is aimed to identify the EPM1 patients with CSTB genetic mutation and hopefully the results of this identification will enable a better understanding of the etiopathogeny and provide with a exact diagnosis of ULD cases.

Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME), Farber Lipogranulomatosis (FL), and a rare variant form of Neonatal Progeroid Syndrome (NPS) are three monogenetic rare disorders caused by pathogenic variation in genes encoding lipid modifying proteins. FL and SMA-PME are caused by loss of function mutations in ASAH1, encoding the acid ceramidase (aCDase) enzyme. It is not, however, known how aCDase deficiency can produce either the isolated neurological symptoms of SMA-PME or the predominantly systemic symptoms of FL. Further, a recently identified variant form of NPS has been attributed to variants in ANO6, encoding a dual function calcium-activated chloride channel and glycerophosphoserine (GPS) scramblase. Here, it is not known how ANO6 mutation causes the premature aging phenotype that defines NPS. To address these questions, I sought to elucidate pathogenic changes in lipid metabolism that associate clinical phenotype. I show here that the different patient mutations in ANO6 cause a non-physiological gain of channel function and either a loss or gain of scramblase function depending on the variant expressed. Both variants, however, alter GPS metabolic homeostasis suggesting a common mechanism of action. To provide in vivo insight, I characterized a novel mouse model based on our NPS patient genetics, showing extremely low penetrance of disease symptoms in terms of live births yet confirming that affected animals show impaired GPS metabolism in affected organs. Next, I characterized the clinical presentation of six new patients with SMA-PME and identified distinct sphingolipid metabolic fingerprints in FL and SMA-PME cells. I show that FL is defined by a hypometabolic sphingolipid phenotype with cellular and molecular features of a classic lysosomal storage disorder. By contrast, SMA-PME has a hypermetabolic sphingolipid phenotype with features of non-classic lysosomal trafficking disorders. To provide clinical insight, I assessed the potential of enzyme replacement therapy, demonstrating a rescue of sphingolipid metabolism in SMA-PME patient cells. Together, this thesis identified changes in the cellular and tissue lipid profiles of patients with ANO6-NPS, SMA-PME, or FL, elucidating some of the lipid-centric pathomechanisms of these diseases.