Reyna M. Durón

Calcific neurocysticercosis and epileptogenesis

Neurocysticercosis is responsible for increased rates of seizures and epilepsy in endemic regions. The most common form of the disease, chronic calcific neurocysticercosis, is the end result of the host’s inflammatory response to the larval cysticercus of Taenia solium. There is increasing evidence indicating that calcific cysticercosis is not clinically inactive but a cause of seizures or focal symptoms in this population. Perilesional edema is at times also present around implicated calcified foci. A better understanding of the natural history, frequency, epidemiology, and pathophysiology of calcific cysticercosis and associated disease manifestations is needed to define its importance, treatment, and prevention.

Prevalence, Incidence, and Etiology of Epilepsies in Rural Honduras: The Salamá Study

Summary:  Purpose: Determination of epilepsy etiology in population‐based studies is difficult because of the high cost of diagnostic tests. However, cost‐effectiveness may be proven if preventive public‐health strategies can be established from the test results. We report an epilepsy population‐based study using clinical and laboratory techniques.

Hyperglycosylation and Reduced GABA Currents of Mutated GABRB3 Polypeptide in Remitting Childhood Absence Epilepsy

Childhood absence epilepsy (CAE) accounts for 10% to 12% of epilepsy in children under 16 years of age. We screened for mutations in the GABA(A) receptor (GABAR) beta 3 subunit gene (GABRB3) in 48 probands and families with remitting CAE. We found that four out of 48 families (8%) had mutations in GABRB3. One heterozygous missense mutation (P11S) in exon 1a segregated with four CAE-affected persons in one multiplex, two-generation Mexican family. P11S was also found in a singleton from Mexico. Another heterozygous missense mutation (S15F) was present in a singleton from Honduras. An exon 2 heterozygous missense mutation (G32R) was present in two CAE-affected persons and two persons affected with EEG-recorded spike and/or sharp wave in a two-generation Honduran family. All mutations were absent in 630 controls. We studied functions and possible pathogenicity by expressing mutations in HeLa cells with the use of Western blots and an in vitro translation and translocation system. Expression levels did not differ from those of controls, but all mutations showed hyperglycosylation in the in vitro translation and translocation system with canine microsomes. Functional analysis of human GABA(A) receptors (alpha 1 beta 3-v2 gamma 2S, alpha 1 beta 3-v2[P11S]gamma 2S, alpha 1 beta 3-v2[S15F]gamma 2S, and alpha 1 beta 3-v2[G32R]gamma 2S) transiently expressed in HEK293T cells with the use of rapid agonist application showed that each amino acid transversion in the beta 3-v2 subunit (P11S, S15F, and G32R) reduced GABA-evoked current density from whole cells. Mutated beta 3 subunit protein could thus cause absence seizures through a gain in glycosylation of mutated exon 1a and exon 2, affecting maturation and trafficking of GABAR from endoplasmic reticulum to cell surface and resulting in reduced GABA-evoked currents.

Novel mutations in Myoclonin1/EFHC1 in sporadic and familial juvenile myoclonic epilepsy

Background: Juvenile myoclonic epilepsy (JME) accounts for 3 to 12% of all epilepsies. In 2004, the GENESS Consortium demonstrated four missense mutations in Myoclonin1/EFHC1 of chromosome 6p12.1 segregating in 20% of Hispanic families with JME. Objective: To examine what percentage of consecutive JME clinic cases have mutations in Myoclonin1/EFHC1. Methods: We screened 44 consecutive patients from Mexico and Honduras and 67 patients from Japan using heteroduplex analysis and direct sequencing. Results: We found five novel mutations in transcripts A and B of Myoclonin1/EFHC1. Two novel heterozygous missense mutations (c.755C>A and c.1523C>G) in transcript A occurred in both a singleton from Mexico and another singleton from Japan. A deletion/frameshift (C.789del.AV264fsx280) in transcript B was present in a mother and daughter from Mexico. A nonsense mutation (c.829C>T) in transcript B segregated in four clinically and seven epileptiform-EEG affected members of a large Honduran family. The same nonsense mutation (c.829C>T) occurred as a de novo mutation in a sporadic case. Finally, we found a three-base deletion (−364○%–362del.GAT) in the promoter region in a family from Japan. Conclusion: Nine percent of consecutive juvenile myoclonic epilepsy cases from Mexico and Honduras clinics and 3% of clinic patients from Japan carry mutations in Myoclonin1/EFCH1. These results represent the highest number and percentage of mutations found for a juvenile myoclonic epilepsy causing gene of any population group. GLOSSARY: CAE = childhood absence epilepsy; FS = febrile seizures in infancy/childhood; GM = grand mal tonic clonic seizure; JME = Juvenile myoclonic epilepsy; PSW = 3–6 Hz polyspike and slow wave complexes; SW = single spike and slow wave complex.

Seizures of Idiopathic Generalized Epilepsies

Summary:  Idiopathic generalized epilepsies (IGEs) comprise at least 40% of epilepsies in the United States, 20% in Mexico, and 8% in Central America. Here, we review seizure phenotypes across IGE syndromes, their response to treatment and advances in molecular genetics that influence nosology. Our review included the Medline database from 1945 to 2005 and our prospectively collected Genetic Epilepsy Studies (GENESS) Consortium database. Generalized seizures occur with different and similar semiologies, frequencies, and patterns, ages at onset, and outcomes in different IGEs, suggesting common neuroanatomical pathways for seizure phenotypes. However, the same seizure phenotypes respond differently to the same treatments in different IGEs, suggesting different molecular defects across syndromes. De novo mutations in SCN1A in sporadic Dravet syndrome and germline mutations in SCN1A, SCN1B, and SCN2A in generalized epilepsies with febrile seizures plus have unraveled the heterogenous myoclonic epilepsies of infancy and early childhood. Mutations in GABRA1, GABRG2, and GABRB3 are associated with absence seizures, while mutations in CLCN2 and myoclonin/EFHC1 substantiate juvenile myoclonic epilepsy as a clinical entity. Refined understanding of seizure phenotypes, their semiology, frequencies, and patterns together with the identification of molecular lesions in IGEs continue to accelerate the development of molecular epileptology.

Reduction in rate of epilepsy from neurocysticercosis by community interventions: The Salamá, Honduras Study

Purpose:  Epilepsy is highly prevalent in developing countries like Honduras, with few studies evaluating this finding. This population‐based study evaluated the impact of an 8‐year public health and educational intervention program in reducing symptomatic epilepsies in rural Salamá, Honduras.

Multiple sclerosis care in Latin America

Before the advent of diagnostic criteria for multiple sclerosis (MS), it was reported that the prevalence of MS in Mexico was “one of the lowest in the world” (1.6/100,000).1 The notion that MS was a rare neurologic disease among those living in the tropics of the Americas and Southern latitudes was widely accepted. The geopolitical boundaries of the region identified as Latin America (LA) extend from the southern border of United States with Mexico (32° North latitude) to the Argentinian and Chilean Patagonia in South America (56° South latitude). The largest Spanish-speaking island countries in the Caribbean—Cuba, Dominican Republic, and Puerto Rico—are also traditionally considered part of LA. The continental mass includes 17 countries with a population of more than 550 million. Due to centuries of racial intermixing, it is a heterogeneous and genetically complex population. The blended cultures of native Amerindians with white Caucasian Europeans and black Africans has resulted in the predominant ethnic Latin American Mestizo. The influence of African genetics is notable in many areas of the subcontinent and the Caribbean. A common observation across LA is the absence of identification of MS in non-mixed Amerindians2; the reason for this phenomenon is unclear.

Developing a neurology training program in Honduras: A joint project of neurologists in Honduras and the World Federation of Neurology

One of the major barriers to the provision of quality care for patients with neurological disorders in developing countries is a low ratio of neurologists per inhabitants, the World Health Organization recommends one neurologist per 100,000. In 1998 Honduras had one neurologist per 325,000 inhabitants and all the neurologists were trained outside the country. The Education Committee of the World Federation of Neurology (WFN), in collaboration with the Postgraduate Direction of the National Autonomous University of Honduras, the Honduran Neurological Association, and the Honduran Secretary of Health helped establish the countrys first Neurology Training Program in 1998. This program was established using a problem- and epidemiological-oriented methodology with oversight by an external WFN review board. By 2006 the program has resulted in a 31% increase in the national neurologist ratio per inhabitant, significantly improved the quality of patient care and promoted research in the neurosciences. The Honduras Neurology Training Program has provided a valuable model for other developing countries with similar needs for neurological care. Based on this Honduras experience, members of the Education Committee of the WFN have established guidelines for neurology training programs in developing countries.

DNA variants in coding region of EFHC1: SNPs do not associate with juvenile myoclonic epilepsy

Purpose:  Juvenile myoclonic epilepsy (JME) accounts for 3 to 12% of all epilepsies. In 2004, we identified a mutation‐harboring Mendelian gene that encodes a protein with one EF‐hand motif (EFHC1) in chromosome 6p12. We observed one doubly heterozygous and three heterozygous missense mutations in EFHC1 segregating as an autosomal dominant gene with 21 affected members of six Hispanic JME families from California and Mexico. In 2006, similar and three novel missense mutations were reported in sporadic and familial Caucasian JME from Italy and Austria. In this study, we asked if coding single nucleotide polymorphisms (SNPs) of EFHC1 also contribute as susceptibility alleles to JME with complex genetics.

Adherence and complementary and alternative medicine use among Honduran people with epilepsy

Adherence to antiepileptic drugs (AEDs) and use of complementary and alternative medicine (CAM) among Hondurans with epilepsy were evaluated. Our epilepsy cohort of 274 outpatients was surveyed to determine demographics, epilepsy treatment history, adherence, and use of CAM. Nonadherence to epilepsy therapy was reported by 121, with unavailability of AEDs (48%) the most common reason. CAM was reportedly used by 141, with prayer, herbs, and potions being common. Forty-nine rural Miskito Hondurans without epilepsy were also interviewed to gain an understanding of their beliefs and longstanding practices regarding epilepsy. Seventeen (34.7%) attributed epilepsy to the supernatural; only three knew of an AED. Widespread nonadherence to evidence-based epilepsy treatments in Honduras can be attributed to inadequate education, AED unavailability, insufficient resources, cultural beliefs, and wide use of CAM. A comprehensive epilepsy education program and improved access to evidence-based AEDs represent initial priorities to improve the Honduran epilepsy treatment gap.