Rumiko Takayama

Loss-of-function mutation of collybistin is responsible for X-linked mental retardation associated with epilepsy

Microarray-based comparative genomic hybridization analysis identified a 737-kb microdeletion of Xq11.1, including the cell division cycle 42 guanine nucleotide exchange factor (GEF)-9 gene (ARHGEF9), encoding collybistin, which has a pivotal role in formation of postsynaptic glycine and γ-aminobutyric acid receptor clusters, in a male patient with severe mental retardation and epilepsy. No overlapping deletion with this was identified in the database of genomic copy number variations. A cohort study of ARHGEF9 nucleotide sequence identified a nonsense mutation in another male patient with severe mental retardation and epilepsy. This mutation affects one of the three transcript variants of ARHGEF9, which was confirmed to be expressed in the brain by reverse transcription-PCR. Although this nonsense mutation was shared with the patients mother, it was not observed in 100 normal individuals. Both male patients suffered epileptic seizures after 1 year of age. Brain magnetic resonance imaging revealed mild frontal atrophy in the first patient and right frontal polymicrogyria in the second patient. Three previously reported mutations of ARHGEF9 consisted of a missense mutation in a male patient with hyperekplexia and two chromosomal disruptions in two female patients. The common phenotypic effects of all ARHGEF9 mutations were mental retardation and epilepsy. Therefore, ARHGEF9 is likely to be responsible for syndromic X-linked mental retardation associated with epilepsy.

Ambroxol chaperone therapy for neuronopathic Gaucher disease: A pilot study

Gaucher disease (GD) is a lysosomal storage disease characterized by a deficiency of glucocerebrosidase. Although enzyme‐replacement and substrate‐reduction therapies are available, their efficacies in treating the neurological manifestations of GD are negligible. Pharmacological chaperone therapy is hypothesized to offer a new strategy for treating the neurological manifestations of this disease. Specifically, ambroxol, a commonly used expectorant, has been proposed as a candidate pharmacological chaperone. The purpose of this study was to evaluate the safety, tolerability, and neurological efficacy of ambroxol in patients with neuronopathic GD.

CDKL5 alterations lead to early epileptic encephalopathy in both genders

Purpose:  Genetic mutations of the cyclin‐dependent kinase‐like 5 gene (CDKL5) have been reported in patients with epileptic encephalopathy, which is characterized by intractable seizures and severe‐to‐profound developmental delay. We investigated the clinical relevance of CDKL5 alterations in both genders.

Retrospective multiinstitutional study of the prevalence of early death in Dravet syndrome.

Purpose:  A questionnaire survey was conducted in Japan to investigate the causes and prevalence of death related to Dravet syndrome.

Long‐term course of Dravet syndrome: A study from an epilepsy center in Japan

This study attempted to clarify the long‐term course of Dravet syndrome (DS).

Mortality in Dravet syndrome: Search for risk factors in Japanese patients

A questionnaire survey was conducted in Japan to investigate the causes and prevalence of death related to Dravet syndrome. The questionnaire was delivered to 246 hospitals at which physicians were treating childhood epilepsy to gain information about the total number of patients with Dravet syndrome and the prevalence of early death due to the disorder. Responses to the survey were collected from 91 hospitals, and a total of 63 of 623 patients with Dravet syndrome had died. Data from 59 of these patients were analyzed. The age at death for these patients ranged from 13 months to 24 years and 11 months, with a median age of 6 years and 8 months. The causes of mortality included sudden death in 31 patients (53%), acute encephalopathy with status epilepticus (SE) in 21 patients (36%), drowning in 6 patients (10%), and other causes in one patient (1%). The incidence of sudden death reached a first peak at 1–3 years of age and a second peak at 18 years and older. In contrast, the incidence of acute encephalopathy with SE reached a peak at 6 years of age. Seven of the 10 patients who underwent SCN1A mutation analysis exhibited positive mutations but exhibited no consistent phenotype. The prevalence of Dravet syndrome–related mortality was 10.1%. The incidence of sudden death and acute encephalopathy with SE was higher in infancy (1–3 years) and at early school ages (with a peak at 6 years), respectively. Neither the treatment nor the number of seizures was associated with any cause of mortality. Factors leading to a fatal outcome are difficult to predict.

Rufinamide as an adjunctive therapy for Lennox—Gastaut syndrome: A randomized double-blind placebo-controlled trial in Japan

PURPOSE To evaluate the efficacy, safety, and pharmacokinetics of rufinamide as an adjunctive therapy for patients with Lennox-Gastaut syndrome (LGS) in a randomized, double-blind, placebo-controlled trial. METHODS We conducted a multicenter clinical trial with a 4-week baseline, a 2-week titration, a 10-week maintenance, and either a follow-up visit or entry into an open-label extension. Patients with LGS (4 to 30 years old) taking between one and three antiepileptic drugs were recruited. After the baseline period, patients were randomly assigned to rufinamide or placebo. The primary efficacy variable was the percent change in the tonic-atonic seizure frequency per 28 days. KEY FINDINGS Of the 59 patients, 29 were randomized to the rufinamide group and 30 to the placebo group. The frequency of epileptic seizures was significantly decreased in the rufinamide group than in the placebo group; the median percent change in frequency of tonic-atonic seizures was -24.2% and -3.3%, respectively, (p=0.003) and that of total seizures was -32.9% and -3.1%, respectively (p<0.001). Subgroup analyses indicated that the efficacy of rufinamide was consistent independent of clinical background characteristics. The common treatment-related adverse events in the rufinamide group were decreased appetite (17.2%), somnolence (17.2%), and vomiting (13.8%). Transient seizure aggravations were observed in 13 (22.0%) of the 59 patients, though a causal relationship with rufinamide was suspected in only one patient. All adverse events were mild to moderate in severity. The mean plasma concentration of rufinamide between 1 and 9 within 12h after administration was 17.2 μg/mL. SIGNIFICANCE The present results showed a favorable risk-benefit profile for rufinamide as an adjunctive therapy for patients with LGS.

Influence of CYP2C19 polymorphism and concomitant antiepileptic drugs on serum clobazam and N-desmethyl clobazam concentrations in patients with epilepsy.

Objective: The aims of this study were to identify the factors influencing the metabolism of clobazam (CLB) and its active metabolite [N-desmethyl clobazam (NCLB)] and to evaluate the NCLB concentration as an indicator for CYP2C19 polymorphism in epileptic patients. Methods: A total of 302 serum samples from 238 Japanese patients were evaluated. The ratios of the serum CLB and NCLB concentrations to the CLB dose (CD ratios) were calculated and compared with CYP2C19 phenotypes. Results: The mean CD ratio of NCLB in extensive metabolizers (EM: *1/*1), intermediate metabolizers (IM: *1/*2 or *1/*3), and poor metabolizers (PM: *2/*2, *3/*3, or *2/*3) was 3.1, 4.9, and 21.6 (&mgr;g/mL)/(mg/kg), respectively. In the EM and IM groups, the concomitant use of hepatic enzyme inducers (phenytoin and carbamazepine) reduced the CD ratio of CLB and increased that of NCLB. In the PM group, these inducers also decreased the CD ratio for CLB but did not elevate the CD ratio for NCLB. Using multiple regression analysis, body weight showed a positive correlation with an increased CD ratio for NCLB. The concomitant use of zonisamide and stiripentol also elevated the CD ratio for NCLB in the EM and IM groups, but that of the PM group was almost unchanged. When the cut-off value of the CD ratio for NCLB was set as 10.0 (&mgr;g/mL)/(mg/kg) for predicting the CYP2C19 PM status, the sensitivity and specificity were 94.4% and 95.7%, respectively. Conclusions: The interaction between NCLB and other antiepileptic drugs showed marked differences among CYP2C19 phenotypes. Measurement of the serum NCLB concentration is clinically useful for identifying the PM phenotype.

Schinzel–Giedion syndrome: A further cause of early myoclonic encephalopathy and vacuolating myelinopathy

Here, we report a male child with Schinzel-Giedion syndrome associated with intramyelinic edema detected on brain magnetic resonance imaging (MRI) and persistent suppression-burst pattern on electroencephalography (EEG) with erratic myoclonus of the extremities and face. Similar to nonketotic hyperglycinemia, Schinzel-Giedion syndrome may be recognized as another causative genetic disease of early myoclonic encephalopathy and vacuolating myelinopathy.

Developmental outcome after surgery in focal cortical dysplasia patients with early-onset epilepsy

The purpose of this study was to investigate the developmental outcome after surgery for early-onset epilepsy in patients with focal cortical dysplasia (FCD). Among 108 patients with histopathologically confirmed FCD operated between 1985 and 2008, we selected 17 patients with epilepsy onset up to 3 years of age. Development was evaluated by the developmental quotient or intelligence quotient (DQ-IQ) and mental age was measured by the Mother-Child Counseling baby test or the Tanaka-Binet scale of intelligence. Postsurgical development outcome was evaluated by the changes in DQ-IQ and mental age as well as rate of increase in mental age (RIMA) after surgery. RIMA was calculated as the increase in mental age per chronological year (months/year; normal average rate: 12 months/year). Age at epilepsy onset of 17 patients ranged from 15 days to 36 months (mean±SD, 11.0±10.0 months). Age at surgery ranged from 18 to 145 months (75.1±32.4 months). Evaluation just before surgery showed that 13 of 17 (76.4%) patients had DQ-IQ below 70. Ten patients (58.8%) were seizure-free throughout the postsurgical follow-up period. After surgery, DQ-IQ was maintained within 10 points of the presurgical level in 13 patients (76.4%), and increased by more than 10 points in one patient (5.9%). After surgery, RIMA in patients with Engels class I (7.5±3.8) was higher than patients with Engels class II-IV (2.6±3.4) (unpaired t-test with Welchs correction, t=2.99, df=15, p=0.0092). RIMA was particularly low in two patients with spasm. In four patients with presurgical DQ-IQ<70, seizure-free after surgery and without spasm, DQ-IQ did not increase but RIMA improved from 3.6±2.8 before surgery to 6.9±2.5 months/year after surgery. RIMA became better from 2 years after surgery. In four patients with presurgical DQ-IQ≥70 and no spasm, two showed the same or higher RIMA than normal average after surgery. In 58.8% of FCD patients with early onset epilepsy, epilepsy surgery effectively controlled seizures, and in 82.3% of patients, epilepsy surgery preserved or improved development. Residual seizures after surgery and lower DQ-IQ before surgery might be potential risk factors for poor development after surgery. In patients of Engels class I with lower presurgical DQ-IQ, catch-up increase in mental age was observed after two years following surgery.