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.

[Juvenile myoclonic epilepsy in chromosome 6p12: clinical and genetic advances]. / Epilepsia mioclónica juvenil del cromosoma 6p12: avances clínicos y genéticos.

Amongst idiopathic generalized epilepsies, juvenile myoclonic epilepsy (JME) is the most common, accounting for 12% to 30% of all epilepsies in the Western world. Classic JME consists of awakening myoclonias, grand mal convulsions and EEG 4 to 6 Hz polyspike waves that appear in adolescence. Probands and affected family members do not have pyknoleptic 3Hz spike and wave absences. However, in 10 to 30% of patients, rare or spanioleptic polyspike wave absences appear. In 1988,1995,1996,we mapped classic JME to a 7 cM locus in chromosome 6p12 11, called EJM1, using families from Los Angeles and Belize. In 2001,we studied one large family from Belize and 21 new families from Los Angeles and Mexico Cities, aided by a BAC/PAC based physical map and 6 new dinucleotide repeats, to narrow EJM1 to an interval between D6S272 and D6S1573. In 2002, we found myoclonin, the putative gene for typical JME in 6p12. At the congress, we will reveal the identity of the myoclonin gene, its putative function and discuss the significance of this discovery in the JME population at large.

Epilepsia mioclónica juvenil en el cromosoma 6p12: avances clínicos y genéticos / Juvenile myoclonic epilepsy in chromosome 6p12: clinical and genetic advances

Entre las epilepsias generalizadas idiopáticas, la epilepsia mioclónica juvenil (EMJ) es la más frecuente y representa el 12-30 por ciento de todas las epilepsias del mundo occidental. La EMJ `clásica' consiste de mioclonía al despertar, crisis convulsivas de gran mal y electroencefalogramas (EEG) con polipunta-ondas de 4 a 6 Hz, que se presentan en la adolescencia. Los probandos y los miembros afectados de la familia no presentan ausencias punta-onda picnolépticas de 3 Hz. Sin embargo, el 10-30 por ciento de los pacientes presentan ausencias polipunta-onda escasas o raras. En 1988, 1995 y 1996 realizamos el mapeo genético de la EMJ `clásica' en un locus de 7 cM en el cromosoma 6p12-11, llamado EMJ1, mediante el empleo de familias de Los Ángeles y Belice. En 2001, estudiamos una familia numerosa de Belice y 21 familias nuevas de Los Ángeles y de Ciudad de México, con la ayuda de un mapa físico basado en recursos BAC/PAC y seis repeticiones dinucleotídicas, para reducir el cromosoma EMJ1 a un intervalo entre los marcadores D6S272 y D6S1573. En 2002, hallamos mioclonín, gen putativo de la EMJ típica en el cromosoma 6p12. En el congreso revelaremos la identidad del gen mioclonín, su función putativa y discutiremos la significación de este descubrimiento en la población con EMJ en general (AU)

Mapping and positional cloning of common idiopathic generalized epilepsies: juvenile myoclonus epilepsy and childhood absence epilepsy.

Among the 40 to 100 million persons with epilepsy worldwide and the 2 to 2.5 million persons with epilepsies in the United States, approximately 50% have generalized epilepsies. Among all epilepsies, the most common are juvenile myoclonus epilepsy (JME) with 10% to 30% of cases, childhood absence epilepsy (CAE) with 5% to 15% of cases, and pure grand mal on awakening with 22% to 37% of cases. In the last decade, six different chromosomal loci for common generalized epilepsies have been identified. These include two separate loci for JME in chromosomes 6p and 15q. The epilepsy locus in chromosome 6p expresses the phenotypes of classic JME, pure grand mal on awakening, and possibly JME mixed with absences. Two separate loci also are present for pyknoleptic CAE, namely, CAE that evolves to JME in chromosome 1p and CAE with grand mal in chromosome 8q24. Pandolfo et al. from the Italian League Against Epilepsy have reported two other putative susceptibility loci for idiopathic generalized epilepsies, namely, grand mal and generalized spike waves 35l in chromosome 3p and generalized epilepsies with febrile convulsions, grand mal, JME, absences, and electroencephalographic spike waves in 8q24. This chapter reports on the debate concerning whether there may be two separate epilepsy loci in chromosome 6p, one in the HLA region and one below HLA. The chapter then discusses the progress made in our laboratories as a result of the Genetic Epilepsy Studies (GENES) International Consortium. We discuss (a) the 2 to 6 cM critical region for classic JME located some 20 cM below HLA in chromosome 6p, (b) the 7-cM area for pyknoleptic CAE that evolves to JME in chromosome 1p, and (c) the 3.2 cM area for pyknoleptic CAE with grand mal and irregular 3 to 4 Hz spike waves in chromosome 8q24. We discusses efforts underway to refine the genetic map of JME in chromosome 6p11 and the advances in physical mapping and positioning of candidate genes, such as the gamma-aminobutyric acid receptor gene, the potassium channel gene of the long-QT family (KvLQT), named KCNQ3, and the human homologue of the mouse jerky gene for CAE in chromosome 8q24 and JME in chromosome 6p11.

Single dose pharmacokinetics of HEPP, a new anticonvulsant in normal healthy volunteers.

The pharmacokinetics and the dose proportionality of a new anticonvulsant compound, HEPP (D,L-3-hydroxy-3-ethyl-3-phenylpropionamide) was studied in healthy male volunteers as part of the pharmacological evaluation for new drugs. Study was performed administering doses of 250, 375, 500 and 625 mg of HEPP to six male volunteers. Blood and urine samples were collected for 72 h postdose and analysed by HPLC. Results showed that in man HEPP is rapidly absorbed from the gastrointestinal tract. Tmax values were between 1.5 and 6.0 h. Plasma mean terminal half-life after the different doses ranged between 15.83 and 27.62 h with an overall harmonic mean value of 22.8. The mean AUC0-infinity and Cmax increased linearly with doses of 250, 375 and 500 mg but not with the dose of 625 mg. The amount of unchanged drug excreted in urine was between 3 and 6% of administered dose which shows an extensive metabolism of the drug.

Juvenile myoclonic epilepsy in chromosome 6p12-p11: locus heterogeneity and recombinations.

We recently analyzed under homogeneity a large pedigree from Belize with classic juvenile myoclonic epilepsy (JME). After a genome wide search with 146 microsatellites, we obtained significant linkage between chromosome 6p markers, D6S257 and D6S272, and both convulsive and EEG traits of JME. Recombinations in two affected members defined a 40 cM JME region flanked by D6S313 and D6S258. In the present communication, we explored if the same chromosome 6p11 microsatellites also have a role in JME mixed with pyknoleptic absences. We allowed for heterogeneity during linkage analyses. We tested for heterogeneity by the admixture test and looked for more recombinations. D6S272, D6S466, D6S294, and D6S257 were significantly linked (Zmax > 3.5) to the clinical and EEG traits of 22 families, assuming autosomal dominant inheritance with 70% penetrance. Pairwise Zmax were 4.230 for D6S294 (theta m = f at 0.133) and 4.442 for D6S466 (theta m = f at 0.111). Admixture test (H2 vs. H1) was significant (P = 0.0234 for D6S294 and 0.0128 for D6S272) supporting the hypotheses of linkage with heterogeneity. Estimated proportion of linked families, alpha, was 0.50 (95% confidence interval 0.05-0.99) for D6S294 and D6S272. Multipoint analyses and recombinations in three new families narrowed the JME locus to a 7 cM interval flanked by D6S272 and D6S257.

Analysis of ELISA hepatitis C virus-positive blood donors population by polymerase chain reaction and recombinant immunoblot assay (RIBA). Comparison of second and third generation RIBA.

A new RIBA-3 (Chiron-Ortho Diagnostic System) was performed for discriminating uninterpretable results of RIBA-2. Recognition of antibodies to hepatitis C virus by RIBA-2 and RIBA-3 was compared among 95 ELISA-2 (second generation ELISA) positive blood donors and correlated with alanine-aminotransferase (ALAT) levels and viremia, using polymerase chain reaction (PCR). These studies led to three important conclusions. First, all ELISA-2-positive, RIBA-2-positive and ALAT-positive samples were found viremic compared with 73% of ELISA-2-positive, RIBA-2-positive and ALAT-negative samples. Then, the comparison of the different RIBAs allowed to conclude that RIBA-3 was more sensitive but less specific than RIBA-2. RIBA-3 was interesting to discriminate undetermined RIBA-2, owing to an improved specificity of C100-3 antigen. In fact, most of the C100-3 positive, RIBA-2 undetermined samples became RIBA-3 negative whereas C22-3 positive, RIBA-2 undetermined samples became RIBA-3 positive or undetermined. Finally, a significant correlation was found between the presence of antibodies against C33-c antigen and viremia.

Comparison of therapeutic regimen of anticysticercal drugs for parenchymal brain cysticercosis.

The efficacy of different regimens of therapy for parenchymal brain cysticercosis either with praziquantel (PZQ) or with albendazole (ALB) was compared in 114 patients. Four schemes of treatment were used: PZQ 50 mg/kg per day for 15 days, PZQ 50 mg/kg per day for 8 days, ALB 15 mg/kg per day for 30 days, and ALB 15 mg/kg per day for 8 days. Three months after therapy, it was apparent that both PZQ and ALB were effective, as shown by the disappearance of cystic lesions in computed tomographic scans. Thirty-three control patients followed for a mean of 11 months had no spontaneous remission of lesions. When comparing PZQ with ALB, the latter was found to be more effective than the former for both the full and the short course of treatment: 85% vs 60% and 85% vs 48% disappearance of lesions, respectively (P less than 0.001). Comparison of the full vs the short course of PZQ showed that the short course had a further 12% reduction in drug effectiveness. In contrast, the length of ALB therapy could be shortened without lessening its efficacy. Based on these results, an 8-day course of ALB is recommended as treatment for parenchymal brain cysticercosis; a 15-day course of PZQ could be subsequently used in those patients who show only partial response to ALB.

Neurocysticercosis as the main cause of late-onset epilepsy in Mexico.

We studied 100 consecutive Mexican patients with epilepsy that started after the age of 25 years. All patients underwent clinical evaluation, computed tomography, and electroencephalography; additionally, cerebrospinal fluid analysis was performed in 82 of them. Neurocysticercosis or its sequelae were diagnosed in 50 patients (50%); 36 of these patients had partial seizures, 41 had parenchymal calcifications, and 15 had two or more lesions. Our results are in contrast with those of most studies from countries with a low incidence of neurocysticercosis, where brain tumors, cerebrovascular disease, trauma, and alcoholism are the main causes of tardive epilepsy.

Praziquantel in the treatment of neurocysticercosis: long-term follow-up.

Thirty-five patients with active neurocysticercosis were treated with praziquantel and followed for 1 year after therapy. CT and CSF analysis showed that 91% of patients with parenchymal cysts improved, and 47% of patients with chronic arachnoiditis had remission. A single treatment with praziquantel for 2 weeks, administered in a daily dose of 50 mg/kg of body weight, was highly effective in parenchymal cysticercosis but less effective in meningeal cysticercosis. The benefits were sustained for at least 1 year.

Therapy of parenchymal brain cysticercosis with praziquantel.

Twenty-six patients with cysticercosis of the brain parenchyma were treated with the antihelmintic agent praziquantel (50 mg per kilogram of body weight daily for 15 days). During treatment a strong inflammatory reaction occurred, as evidenced by increased protein and cells in the cerebrospinal fluid. This finding correlated with headache, exacerbation of neurologic symptoms, and edema and inflammation around cystic lesions. After three months of treatment all patients had improved clinically, and 13 (50 per cent) were asymptomatic. The total number of cysts on CT scans had decreased from 152 at the beginning of treatment to 51, and the mean diameter of cysts was reduced by 72 per cent. CT scans showed improvement in 25 of the 26 patients, with total remission of all cysts in nine. Seventeen control patients followed with CT studies for a mean of 9 +/- 2 months had no spontaneous remission of lesions, and in many cases the scans showed worsening during the observation period. Our results indicate that praziquantel is effective in cysticercosis of the brain parenchyma.