receptors that are localized outside of the synapse). Among the mutations that have been reported in this in this gene, one (R220H) has been identified in a small family with JME. This mutation affects GABAergic transmission by altering the surface expression of the receptor as well as reducing the channel – opening duration. Myoclonin1/EFHC1
The final known associated gene is EFHC1. Myoclonin1/EFHC1 encodes for a protein that has been known to play a wide range of wild-type cell division, neuroblast migration and synapse/dendrite formation. EFHC1 is expressed in many tissues, including the brain, where it is localized to the soma and dendrites of neurons, particularly the hippocampal CA1 region, pyramidal neurons in the cerebral cortex, and Purkinje cells in the cerebellum.There are four JME-causing mutations discovered (D210N, R221H, F229L and D253Y). The mutations do not seem to alter the ability of the protein to colocalize with centrosomes and mitotic spindles but induce mitotic spindle defects. Moreover, the mutations impact radial and tangential migration during brain development. As such a theory has been put forward that JME may be the result of a brain developmental disorder. Other loci
Three SNP alleles in BRD2, Cx-36 and ME2 and microdeletions in 15q13.3, 15q11.2 and 16p.13.11 also contribute risk to JME. Diagnosis
Diagnosis is typically made based on patient history. The physical examination is usually normal. The primary diagnosis for JME is a good knowledge of patient history  and the neurologists familiarity with the myoclonic jerks, which are the hallmark of the syndrome.
A long-term population-based study suggested that at 25 years from seizure onset all seizure types in JME resolved in 17% and in 13% only myoclonus remained despite discontinuing medication. Thus, disabling seizures resolve in around one-third of patients. Signs and symptoms
There are three principle seizures types which may occur in JME: myoclonus, generalized tonic-clonic seizures and absence seizures. Approximately one-third of patients have all three seizure types. The majority of patients (58.2%) have frequent myoclonic jerks and uncommon generalized tonic-clonic seizures. Absence seizures are believed to be the least common with studies estimating a prevalence of 10% to as high as 38%. Myoclonic status epilepticus may occur as a complication but it is uncommon. Patient’s typically initially present to medical providers following their first generalized tonic-clonic seizure. It is often subsequently reported that the patient was having myoclonus for several years prior. The first generalized tonic-clonic seizure usually occurs in the context of a particular provoking factor such as sleep deprivation, stress or alcohol consumption. There are other potential provoking factors such as praxis induction which refers to the precipitation of seizures or epileptiform discharges in the context of a complex cognitive tasks. Patients with JME tend to perform worse on neuropsychological assessments in multiple cognitive domains and are also more likely to have psychiatric comorbidities such as depression and anxiety when compared to control populations. The majority of patients with JME report satisfaction with their health, work, friendships and social life.