Association of variants in the ABCB1, CYP2C19 and CYP2C9 genes for Juvenile Myoclonic Epilepsy.

Juvenile myoclonic epilepsy (JME) is the most common of the generalized genetic epilepsies, with multiple causal and susceptibility genes; however, its etiopathogenesis is mainly unknown. The toxic effects caused by xenobiotics in cells occur during their metabolic transformation, mainly by enzymes belonging to cytochrome P450. The elimination of these compounds by transporters of the ABC type protects the central nervous system, but their accumulation causes neuronal damage, resulting in neurological diseases. The present study has sought the association between single nucleotide genetic variants of the CYP2C9, CYP2C19, and ABCB1 genes and the development of JME in patients compared to healthy controls. The CC1236 and GG2677 genotypes of ABCB1 in women; allele G 2677, genotypes GG 2677 and CC 3435 in men; the CYP2C19*2A allele, and the CYP2C19*3G/A genotype in both sexes were found to be risk factors for JME. Furthermore, carriers of the TTGGCC genotype combination of the ABCB1 gene (1236/2677/3435) have a 10.5 times higher risk of developing JME than non-carriers. Using the STRING database, we found an interaction between the proteins encoded by these genes and other possible proteins. These findings indicate that the CYP450 system and ABC transporters could interact with other genes in the JME.

Unraveling the role of relative telomere length and CAG expansion on initial symptoms of juvenile Huntington disease.

BACKGROUND AND PURPOSE: Juvenile-onset Huntington disease (JHD) is defined when symptoms initiate before 20 years of age. Mechanisms explaining differences between juvenile and adult onset are not fully understood. Our aim was to analyze the distribution of initial symptoms in a cohort of JHD patients and to explore its relationship with CAG expansion and relative telomere length (RTL). METHODS: A total of 84 JHD patients and 54 neurologically healthy age and sex matched individuals were recruited. CAG length was measured by southern blot or triplet repeat primed polymerase chain reaction. RTL was measured using the Cawthon method. RESULTS: Psychiatric symptoms were most frequent when considering the entire cohort. When divided into onset before or after 10 years, cognitive symptoms were more frequent in the youngest, whilst in the older group psychiatric symptoms prevailed. Motor symptoms were rare in the youngest and epilepsy was observed only in this group as well as a larger CAG expansion. RTL analysis revealed shorter telomeres in JHD patients compared to controls. This difference is not influenced by age, initial symptoms, time of disease or CAG expansion. CONCLUSIONS: To the best of our knowledge this is the largest cohort of JHD patients reported. Psychiatric manifestations deserve special attention when JHD is suspected and epilepsy is especially important in the youngest patients. Initial symptoms seem to be influenced by CAG expansion and therefore age of onset. RTL is significantly reduced in JHD patients which can influence the characteristic neurodegeneration of JHD and contribute to the clinical discrepancy between adult and juvenile forms of Huntington disease.

Low quality of life, increased number of anti-seizure drugs, and the lack of caregiver support are associated with internalized stigma in adult Mexican patients with epilepsy.

BACKGROUND: People with epilepsy (PWE) have been subject to stigma throughout history, a factor that could compromise their performance in daily life. In Mexico, little is known about the factors that may be affecting internalized stigma. OBJECTIVE: To evaluate the internalized stigma in adult PWE, its relationship with the quality of life, cognitive and depressive symptomatology, and clinical-demographic characteristics. MATERIAL AND METHODS: We conducted a cross-sectional study with a consecutive sampling approach in patients with epilepsy treated at the National Institute of Neurology and Neurosurgery Manuel Velasco Suárez (NINNMVS). Sociodemographic and clinical data, depressive symptomatology (Beck's depression inventory, DBI), cognition (MoCA test), quality of life (QOLIE-31 scale), and internalized stigma (King's internalized stigma scale, ISS) were evaluated. Correlations were made between the continuous variables and the ISS to select those with statistical significance and include them in a multiple linear regression model, along with the dummy variables, to explain internalized stigma. RESULTS: Of 128 patients, 74 (58%) were women; 38% of the patients had more than 20 years of epilepsy evolution. In addition, 39% presented depressive symptoms, and around 60% manifested a possible cognitive impairment. The variables that showed statistical significance concerning the ISS were selected along with dummy variables for multiple linear regression analysis. The resultant model considers the QOLIE-31 total score (ß = -0.489), the number of anti-seizure drugs (ASD, ß = 0.253), and those patients without caregiver support (ß = -0.166) with an adjusted R2 value of 0.316. CONCLUSIONS: A diminishing quality of life, an increased number of ASD, and patients without caregiver support influence a slight to moderate variation of internalized stigma in Mexican PWE. Therefore, it is necessary to continue studying other possible factors that influence internalized stigma to generate effective strategies to reduce its negative effects on PWE.

Variant Intestinal-Cell Kinase in Juvenile Myoclonic Epilepsy.

BACKGROUND: In juvenile myoclonic epilepsy, data are limited on the genetic basis of networks promoting convulsions with diffuse polyspikes on electroencephalography (EEG) and the subtle microscopic brain dysplasia called microdysgenesis. METHODS: Using Sanger sequencing, we sequenced the exomes of six members of a large family affected with juvenile myoclonic epilepsy and confirmed cosegregation in all 37 family members. We screened an additional 310 patients with this disorder for variants on DNA melting-curve analysis and targeted real-time DNA sequencing of the gene encoding intestinal-cell kinase ( ICK). We calculated Bayesian logarithm of the odds (LOD) scores for cosegregating variants, odds ratios in case-control associations, and allele frequencies in the Genome Aggregation Database. We performed functional tests of the effects of variants on mitosis, apoptosis, and radial neuroblast migration in vitro and conducted video-EEG studies in mice lacking a copy of Ick. RESULTS: A variant, K305T (c.914A→C), cosegregated with epilepsy or polyspikes on EEG in 12 members of the family affected with juvenile myoclonic epilepsy. We identified 21 pathogenic ICK variants in 22 of 310 additional patients (7%). Four strongly linked variants (K220E, K305T, A615T, and R632X) impaired mitosis, cell-cycle exit, and radial neuroblast migration while promoting apoptosis. Tonic-clonic convulsions and polyspikes on EEG resembling seizures in human juvenile myoclonic epilepsy occurred more often in knockout heterozygous mice than in wild-type mice (P=0.02) during light sleep with isoflurane anesthesia. CONCLUSIONS: Our data provide evidence that heterozygous variants in ICK caused juvenile myoclonic epilepsy in 7% of the patients included in our analysis. Variant ICK affects cell processes that help explain microdysgenesis and polyspike networks observed on EEG in juvenile myoclonic epilepsy. (Funded by the National Institutes of Health and others.).

Increased non-attendance at epilepsy clinic in patients with neuropsychiatric comorbidities: A prospective study.

BACKGROUND: In patients with epilepsy, regular follow-up is vital for adequate seizure control, antiseizure drugs' (ASDs) side effects, psychiatric comorbidities, and planning for epilepsy surgery. Non-attendance creates barriers to adequate patient care, inefficient allocation of resources, loss of income, and unnecessary emergency department visits due to lack of seizure control. This study aimed to determine the causes and sociodemographic characteristics of the non-attendant population at the Epilepsy Clinic. METHODS: A prospective and observational study was carried out on patients treated at the Epilepsy Clinic of the National Institute of Neurology and Neurosurgery (NINN) in Mexico from August 2015 to June 2016. A phone interview was made with all those patients who did not attend the epilepsy consultation. This call incorporated ad hoc questions to meet the objectives of this study. RESULTS: During the study period, 1299 patients had an appointment at the epilepsy clinic, where 233 (17.9%) patients missed their consultation, 123 (52.8%) were male, mean age was 35.9 ±â€¯14.42 years. The most frequent cause of non-attendance was forgetfulness of the appointment in 62 patients (26.6%). Two patients died; no patient was reported to have experienced SUDEP. Non-attendant patients showed statistically significant overall prevalence of psychiatric comorbidities (41.6%), particularly depression, anxiety, and interictal psychosis. CONCLUSION: Information on non-attendance at various specialist consultations is scarce, and to our knowledge, this is the first study to address non-attendance in patients with epilepsy in Latin America. Improving hospital protocols to reduce non-attendance can increase patient adherence to follow-up, ultimately improving the quality of care in the epilepsy clinic.

Electroencephalographic findings in asymptomatic relatives of patients with juvenile myoclonic epilepsy: relationship with the degree of kinship.

INTRODUCTION: A prevalence of 1 to 71% of electroencephalogram (EEG) abnormalities has been reported in asymptomatic relatives of patients with juvenile myoclonic epilepsy (JME). OBJECTIVE: To determine the frequency of EEG abnormalities in asymptomatic relatives of patients with JME according to the degree of kinship. METHODS: Prospective, analytical study. First-, second, and third-degree relatives of patients with JME who agreed to participate and signed informed consent were included. The analysis was descriptive, bivariate. RESULTS: 209 asymptomatic relatives were included, out of which 115 (55%) were females and 94 (45%) were males, with a mean age of 35.9 ± 16.9 (range between 6 and 73 years). Forty-four (21.1%) relatives had abnormal EEGs. First-degree relatives (12%) had abnormalities more frequently in comparison with second- and third-degree relatives (p = 0.007). CONCLUSIONS: EEG abnormalities were observed in one third of asymptomatic relatives. It is important to highlight that there were more alterations among first-degree relatives. In the future, these findings might enable for the risk of clinically developing the disease to be estimated and for genetic counseling to be provided.

INTRODUCCIÓN: Se ha reportado de 1 a 71 % de prevalencia de anormalidades en el electroencefalograma (EEG) de familiares asintomáticos de pacientes con epilepsia mioclónica juvenil (EMJ). OBJETIVO: Determinar la frecuencia de anormalidades en el EEG en familiares asintomáticos de pacientes con EMJ de acuerdo con el grado de parentesco. MÉTODOS: Estudio prospectivo y analítico. Se incluyeron familiares de primer, segundo y tercer grado de pacientes con EMJ, quienes aceptaron participar y firmaron el consentimiento informado. El análisis fue descriptivo bivariado. RESULTADOS: Se incluyeron 209 familiares asintomáticos, 115 (55 %) mujeres y 94 (45 %) hombres, con edad media de 35.9 ± 16.9 (rango entre seis y 73 años); 44 familiares (21.1 %) tuvieron EEG anormal. Los familiares de primer grado (12 %) cursaron con mayor frecuencia con anormalidades en comparación con los de segundo y tercer grado (p = 0.007). CONCLUSIONES: Se observaron anormalidades en el EEG de una tercera parte de los familiares asintomáticos. Es importante resaltar que existieron más alteraciones entre los familiares de primer grado. En un futuro, estos hallazgos permitirán estimar el riesgo de desarrollar la enfermedad clínicamente y brindar consejo genético.

EFHC1 variants in juvenile myoclonic epilepsy: reanalysis according to NHGRI and ACMG guidelines for assigning disease causality.

PURPOSE: EFHC1 variants are the most common mutations in inherited myoclonic and grand mal clonic-tonic-clonic (CTC) convulsions of juvenile myoclonic epilepsy (JME). We reanalyzed 54 EFHC1 variants associated with epilepsy from 17 cohorts based on National Human Genome Research Institute (NHGRI) and American College of Medical Genetics and Genomics (ACMG) guidelines for interpretation of sequence variants. METHODS: We calculated Bayesian LOD scores for variants in coinheritance, unconditional exact tests and odds ratios (OR) in case-control associations, allele frequencies in genome databases, and predictions for conservation/pathogenicity. We reviewed whether variants damage EFHC1 functions, whether efhc1-/- KO mice recapitulate CTC convulsions and "microdysgenesis" neuropathology, and whether supernumerary synaptic and dendritic phenotypes can be rescued in the fly model when EFHC1 is overexpressed. We rated strengths of evidence and applied ACMG combinatorial criteria for classifying variants. RESULTS: Nine variants were classified as "pathogenic," 14 as "likely pathogenic," 9 as "benign," and 2 as "likely benign." Twenty variants of unknown significance had an insufficient number of ancestry-matched controls, but ORs exceeded 5 when compared with racial/ethnic-matched Exome Aggregation Consortium (ExAC) controls. CONCLUSIONS: NHGRI gene-level evidence and variant-level evidence establish EFHC1 as the first non-ion channel microtubule-associated protein whose mutations disturb R-type VDCC and TRPM2 calcium currents in overgrown synapses and dendrites within abnormally migrated dislocated neurons, thus explaining CTC convulsions and "microdysgenesis" neuropathology of JME.Genet Med 19 2, 144-156.

High-dose versus low-dose valproate for the treatment of juvenile myoclonic epilepsy: Going from low to high.

Juvenile myoclonic epilepsy (JME) is a genetic generalized epilepsy accounting for 3-12% of adult cases of epilepsy. Valproate has proven to be the first-choice drug in JME for controlling the most common seizure types: myoclonic, absence, and generalized tonic-clonic (GTC). In this retrospective study, we analyzed seizure outcome in patients with JME using valproate monotherapy for a minimum period of one year. Low valproate dose was considered to be 1000mg/day or lower, while serum levels were considered to be low if they were at or below 50mcg/dl. One hundred three patients met the inclusion criteria. Fifty-six patients (54.4%) were female. The current average age was 28.4±7.4years, while the age of epilepsy onset was 13.6±2.9years. Most patients corresponded to the subsyndrome of classic JME. Forty-six (44.7%) patients were free from all seizure types, and 76 (73.7%) patients were free from GTC seizures. No significant difference was found in seizure freedom among patients using a low dose of valproate versus a high dose (p=0.535) or among patients with low blood levels versus high blood levels (p=0.69). In patients with JME, it seems appropriate to use low doses of valproate (500mg to 1000mg) for initial treatment and then to determine if freedom from seizures was attained.

Presymptomatic Testing for Huntington's Disease in Mexico: 28 Years of Experience.

INTRODUCTION: Huntington's disease (HD) is a genetic neurodegenerative disorder with dominant inheritance. Our center in Mexico City has offered presymptomatic testing (PT) since 1995. OBJECTIVE: To describe the main clinical and demographic characteristics of at-risk HD individuals who applied to the PT program, the reasons for seeking it, and the molecular results. METHODS: A cross-sectional study was conducted with sociodemographic and clinical data of all PT applicants from 1995-2023. Reasons for seeking PT were assessed using a modified questionnaire. In addition, anxiety, and depressive symptoms before and after PT were evaluated with Beck's instruments; cognitive impairment (CI) was assessed with the Mini-Mental State Examination (MMSE) and molecular results. RESULTS: 214 people applied for PT (2.1% of the at-risk population identified in our center); 63% were women (mean age of 37.11 years). 204 (95.3%) were accepted and 190 received results. 70% indicated that the main reason for applying for PT was to inform their offspring about the risk of inheriting HD. Significant differences were observed in the reasons for seeking PT by age group. Although some subjects received treatment, Beck's instrument scores did not indicate special attention or pharmacological treatment. The MMSE showed probable CI in 20 subjects. Of those who received results, 37% were carriers of a full penetrance allele. CONCLUSION: Our center has the only formal PT program for HD in Mexico. The reasons for seeking PT are varied and age-related. Although PT is offered to all subjects at risk for HD, uptake remains low.

Mutations in EFHC1 cause juvenile myoclonic epilepsy.

Juvenile myoclonic epilepsy (JME) is the most frequent cause of hereditary grand mal seizures. We previously mapped and narrowed a region associated with JME on chromosome 6p12-p11 (EJM1). Here, we describe a new gene in this region, EFHC1, which encodes a protein with an EF-hand motif. Mutation analyses identified five missense mutations in EFHC1 that cosegregated with epilepsy or EEG polyspike wave in affected members of six unrelated families with JME and did not occur in 382 control individuals. Overexpression of EFHC1 in mouse hippocampal primary culture neurons induced apoptosis that was significantly lowered by the mutations. Apoptosis was specifically suppressed by SNX-482, an antagonist of R-type voltage-dependent Ca(2+) channel (Ca(v)2.3). EFHC1 and Ca(v)2.3 immunomaterials overlapped in mouse brain, and EFHC1 coimmunoprecipitated with the Ca(v)2.3 C terminus. In patch-clamp analysis, EFHC1 specifically increased R-type Ca(2+) currents that were reversed by the mutations associated with JME.

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.

circRNA Regulates Dopaminergic Synapse, MAPK, and Long-term Depression Pathways in Huntington Disease.

Huntington disease (HD) is the most common neurogenetic disorder caused by expansion of the CAG repeat in the HTT gene; nevertheless, the molecular bases of the disease are not fully understood. Non-coding RNAs have demonstrated to be involved in the physiopathology of HD. However, the role of circRNAs has not been investigated. The aim of this study was to identify the circRNAs with differential expression in a murine cell line model of HD and to identify the biological pathways regulated by the differentially expressed circRNAs. CircRNA expression was analyzed through a microarray, which specifically detects circular species of RNA. The expression patterns between a murine cell line expressing mutant Huntingtin and cells expressing wild-type Huntingtin were compared. We predicted the miRNAs with binding sites for the differentially expressed circRNAs and the corresponding target genes for those miRNAs. Using the target genes, we performed a function enrichment analysis. We identified 23 circRNAs differentially expressed, 19 downregulated and four upregulated. Most of the downregulated circRNAs derive from the Rere gene. The dopaminergic synapse, MAPK, and long-term depression pathways were significantly enriched. The three identified pathways have been previously associated with the physiopathology of HD. The understanding of the circRNA-miRNA-mRNA network involved in the molecular mechanisms driving HD can lead us to identify novel biomarkers and potential therapeutic targets. To the best of our knowledge, this is the first study analyzing circRNAs in a model of Huntington disease.

Telomere length analysis on leukocytes derived from patients with Huntington Disease.

INTRODUCTION: Huntington´s disease (HD) is a neurodegenerative disorder characterized by neuropsychiatric, motor and cognitive manifestations. It is caused by expansion of the trinucleotide CAG on HTT. The molecular bases are not completely understood, DNA damage, such as double and single strand breaks and oxidative stress (OS) have been implicated. At telomeres, DNA breaks are less efficiently repaired. Double strand breaks evoke the break induced replication (BIR) mechanism. BIR, plus inefficient repair can produce telomere shortening and cellular senescence. Our aim was to investigate the correlation between leukocyte relative telomeric length (RTL) and HD. METHODS: 206 samples were analyzed, 71 patients with molecular diagnosis and symptomatology (HD), 29 individuals with positive molecular test but asymptomatic (PP) and 106 healthy individuals (NP). RESULTS: We found a significant difference in RTL between HD patients compared with both, PP and NP, independently of subjects' age. DISCUSSION: Here we present evidence supporting an association between telomere shortening and HD. Telomere shortening could be related to DNA damage caused by ROS and defective DNA repair mechanism. Both events have been probed to occur in the presence of a mutant Huntingtin. This study contributes with current evidence suggesting a potential role of telomere shortening as HD biomarker.

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. METHODS: We screened using denaturing high-performance liquid chromatography (DHPLC) and then directly sequenced the 11 exons of EFHC1 in 130 unrelated JME probands, their 352 family members, and seven exons of EFHC1 in 400-614 ethnically matched controls. We carried out case-control association studies between 124 unrelated Hispanic JME probands and 552-614 ethnically matched controls using four SNPs, rs3804506, rs3804505, rs1266787, and rs17851770. We also performed family-based association on SNPs rs3804506 and rs3804505 in 84 complete JME families using the Family-Based Association Test (FBAT) program. RESULTS: We found no statistically significant differences between JME probands and controls in case-control association and no genetic transmission disequilibria in family-based association for the tested SNPs. In addition, we identified four new DNA variants in the coding region of EFHC1. CONCLUSION: The four coding SNPs, rs3804506, rs3804505, rs1266787, and rs17851770, of EFHC1 may not be susceptibility alleles for JME.

Mutation analyses of genes on 6p12-p11 in patients with juvenile myoclonic epilepsy.

Juvenile myoclonic epilepsy (JME) is a distinct form of idiopathic generalized epilepsy (IGE). One of the candidate regions for human JME has been mapped on chromosome band 6p11-p12 by linkage analyses and is termed EJM1 (MIM 254770). Recently, we reported the reduction of the EJM1 region to 3.5cM that contains 18 genes, the exclusion of three genes (LRRC1, GCLC, KIAA0057) by mutation analyses, and the identification of Myoclonin1/EFHC1 as the EJM1 gene. Here, we describe detailed physical and transcriptome maps of the 3.5cM EJM1 region, and detailed results of mutation analyses for the remained 14 genes (HELO1, GCMA, KIAA0936, FBXO9, GSTA3, GSTA4, PTD011, KIAA0576, LMPB1, IL17F, MCM3, PKHD1, KIAA0105, TFAP2B) in patients with JME. We identified 49 single nucleotide changes in eight genes. Twelve amino acid substitutions occurred in two genes, 11 silent mutations in seven genes, and 26 in the non-coding or intronic regions of seven genes. Twelve amino acid substitutions in the two genes (IL17F, PKHD1) were also observed in healthy control individuals or did not co-segregate with the disease phenotypes in other family members. Thus, the absence of significant and potentially functional mutations in the remaining 14 genes further supports the concept that Myoclonin1/EFHC1 is the EJM1 gene in chromosome 6p12.

TGFBR2 mutation and MTHFR-C677T polymorphism in a Mexican mestizo population with cervico-cerebral artery dissection.

Spontaneous cervico-cerebral artery dissection (CCAD) is a common condition found among young patients with ischemic stroke. We examined the possible association between the polymorphism of methylenetetrahydrofolate reductase (MTHFR)-C677T and the gene mutation in transforming growth factor beta receptor II (TGFBR2) in a cohort of CCAD patients. One-hundred CCAD cases (65 males; mean age: 38.08 ± 10.68 years) and 100 matching controls were included. Ancestry informative markers (AIMs) were used to increase internal validity of the genetic analysis. Genotypes of the C677T polymorphism in the MTHFR gene were determined by polymerase chain reaction and restriction fragment length polymorphism; direct sequencing was used for a mutation analysis of the TGFBR2 gene. Associations were evaluated using a multivariate statistics, and Hardy-Weinberg equilibrium was analyzed. We also incorporated our data into a meta-analysis of the MTHFR-C677T. Sixty-three patients presented with vertebral and 37 with carotid artery dissection. Ancestry markers found a call rate on each over 95 %. All AIMs did not deviate from Hardy-Weinberg equilibrium (p > 0.05). The homozygous TT genotype was more frequent in cases (OR 2.04, CI 95 % 1.53-2.72, p = 0.005), whereas no significant difference was found on heterozygous CT genotype. TGFBR2 mutation was not present in our samples. In the meta-analysis of MTHFR/C677T variant, a total 613 cases and 1547 controls were analyzed; we found a moderate association for the recessive model genotype (OR 2.04, CI 95 % 1.53-2.72; p = 0.342; Z = 4.83; I (2) = 11.3). This study supports a positive association between the MTHFR-C677T polymorphism and genetically confirmed Mexican mestizo CCAD patients.

Chromosome loci vary by juvenile myoclonic epilepsy subsyndromes: linkage and haplotype analysis applied to epilepsy and EEG 3.5-6.0 Hz polyspike waves.

Juvenile myoclonic epilepsy (JME), the most common genetic epilepsy, remains enigmatic because it is considered one disease instead of several diseases. We ascertained three large multigenerational/multiplex JME pedigrees from Honduras with differing JME subsyndromes, including Childhood Absence Epilepsy evolving to JME (CAE/JME; pedigree 1), JME with adolescent onset pyknoleptic absence (JME/pA; pedigree 2), and classic JME (cJME; pedigree 3). All phenotypes were validated, including symptomatic persons with various epilepsies, asymptomatic persons with EEG 3.5-6.0 Hz polyspike waves, and asymptomatic persons with normal EEGs. Two-point parametric linkage analyses were performed with 5185 single-nucleotide polymorphisms on individual pedigrees and pooled pedigrees using four diagnostic models based on epilepsy/EEG diagnoses. Haplotype analyses of the entire genome were also performed for each individual. In pedigree 1, haplotyping identified a 34 cM region in 2q21.2-q31.1 cosegregating with all affected members, an area close to 2q14.3 identified by linkage (Z max = 1.77; pedigree 1). In pedigree 2, linkage and haplotyping identified a 44 cM cosegregating region in 13q13.3-q31.2 (Z max = 3.50 at 13q31.1; pooled pedigrees). In pedigree 3, haplotyping identified a 6 cM cosegregating region in 17q12. Possible cosegregation was also identified in 13q14.2 and 1q32 in pedigree 3, although this could not be definitively confirmed due to the presence of uninformative markers in key individuals. Differing chromosome regions identified in specific JME subsyndromes may contain separate JME disease-causing genes, favoring the concept of JME as several distinct diseases. Whole-exome sequencing will likely identify a CAE/JME gene in 2q21.2-2q31.1, a JME/pA gene in 13q13.3-q31.2, and a cJME gene in 17q12.

Identification and mutational analysis of candidate genes for juvenile myoclonic epilepsy on 6p11-p12: LRRC1, GCLC, KIAA0057 and CLIC5.

Juvenile myoclonic epilepsy (JME) is one of the most frequent hereditary epilepsies characterized by myoclonic and tonic-clonic convulsions beginning at 8-20 years of age. Genetic studies have revealed four major chromosomal loci on 6p21.3, 6p11-12, 6q24, and 15q14 as candidate regions harboring genes responsible for JME. Previously we reported the region on 6p11-p12 (EJM1), and here we report the identification and mutational analysis of candidate genes for EJM1. One of those is a leucine-rich repeat-containing 1 (LRRC1) gene that is composed of 14 exons and codes for 524 amino acid residues. In Northern analysis, 7 kb transcripts of LRRC1 gene were detected in multiple tissues, most strongly, in heart, lung, and kidney. Mutation analysis of LRRC1 gene in 20 JME patients from ten families revealed one nucleotide substitution that lead to amino acid exchange (c.577 A>G; Ile193Val). This variation, however, did not co-segregate with the disease phenotype. We further performed mutational analyses of CLIC5, KIAA0057 and GCLC genes in or flank to the EJM1 region. These analyses did not provide any evidences that these genes are responsible for the JME phenotype, and suggested that these may not be the EJM1 gene.

Homocysteine-induced brain lipid peroxidation: effects of NMDA receptor blockade, antioxidant treatment, and nitric oxide synthase inhibition.

The effect of homocysteine (HCY) on lipid peroxidation (LP), a current mechanism of oxidative neurotoxicity, was investigated in rat brain synaptosomes. LP was assessed by measuring the amount of thiobarbituric acid-reactive substances (TBARS) formed from synaptosomal fractions following HCY treatment. Increasing HCY concentrations (5-1000 micro M) enhanced the TBARS formation in brain synaptosomes in a concentration-dependent manner. When compared at equimolar concentrations (100 micro M), the oxidative potency of HCY was lower than that of the oxidant ferrous sulfate, similar to that produced by glutamate (Glu) and the mitochondrial toxin 3-nitropropionic acid, and higher than that of the Glu agonists, kainate and quinolinate. The N-methyl-D-aspartate receptor (NMDAr) antagonist dizocilpine (MK-801) completely blocked the HCY-induced LP at concentrations between 5 to 1000 micro M, whereas the well-known antioxidant N-acetylcysteine (NAC) was less effective, but still protective against the HCY oxidative toxicity at higher concentrations (400 and 1000 micro M). Three nitric oxide synthase (NOS) inhibitors, 7-nitroindazole (7-NI), Nomega-nitro-L-arginine (L-NARG) and Nomega-nitro-L-arginine methyl ester (L-NAME), were also tested on HCY-induced LP at increasing concentrations. Both nonspecific NOS inhibitors (L-NARG and L-NAME) decreased more effectively the HCY-induced LP than did the selective neuronal NOS inhibitor, 7-NI. These results show that submillimolar concentrations of HCY can induce oxidative injury to nerve terminals, and this effect involves NMDAr stimulation, NOS activation, and associated free radicals formation.