Autosomal dominant cortical tremor, myoclonus, and epilepsy (ADCME) in a unique south Indian community

Abstract

Summary Autosomal dominant cortical tremor, myoclonus, and epilepsy (ADCME)/familial adult onset myoclonic epilepsy (FAME) is a nonprogressive disorder characterized by (1) distal tremors that are usually precipitated by posture and action; (2) stimulus‐sensitive myoclonus that is predominantly seen in the upper limb and is precipitated by photic stimuli, fatigue, emotional stress, and sleep deprivation; (3) seizures that were predominantly of the generalized tonic–clonic type that showed significant response to antiepileptic drugs (AEDs). ADCME has been reported worldwide with different genetic loci in Japanese families (8q23.3‐q24.1), Italian families (2p11.1‐q12.2), a French family (5p15.3.1‐p15.1), and a Thai family (3q26.32‐q28). ADCME has not been reported in South India and is still not recognized as an independent entity under the International League Against Epilepsy (ILAE). We report 241 patients with ADCME identified belonging to 48 families. The 48 families are domiciled in two southern districts of Tamilnadu in India, belonging to a community called “Nadar” whose nativity is confined to these southern districts, with reported unique genetic characteristics. This study is reported for the presentation of this rare disease in a unique ethnic group, and is the largest single report on ADCME worldwide.

Autosomal dominant cortical tremor, myoclonus and epilepsy

“…The 48 families are domiciled in 2 southern districts of Tamilnadu, India, which belongs to the Nadar community, and their origin is confined to these southern districts, with reported unique genetic characteristics. This is the largest single report of ADCME worldwide (Mahadevan et al ., ).…”

Clinical and neurophysiological features of familial cortical myoclonic tremor with epilepsy

“…Characterized by the cortical origin and tremulous movement, we will term this involuntary finger movement as “cortical tremor” in the rest of the text. FCMTE has been reported worldwide, including China, Japan, Italy, France, The Netherlands, South Africa, Spain, Turkey, Thailand, and India . However, it is still a rare epilepsy syndrome, involving a limited number of patients reported and unknown genetic etiology.…”

Familial Cortical Myoclonic Tremor and Epilepsy, an Enigmatic Disorder: From Phenotypes to Pathophysiology and Genetics. A Systematic Review

“…Stimulus-sensitive myoclonus, frequently present in FCMTE, may be triggered or worsened by alcohol, emotional stress, sleep deprivation, tactile stimuli, and photic/phonic stimulation. 16 , 17 , 21 , 37 , 47 , 56 , 57 , 62 Twitching movements can involve facial/axial muscles. 16 , 21 , 57 , 58 Alcohol responsiveness has been reported in two pedigrees.…”

“…Epileptic seizures are usually generalized tonic–clonic seizures, but can also be complex partial seizures. 8 , 37 , 46 , 56 Recently the latter were renamed as focal seizures with impaired awareness (International League Against Epilepsy [ILAE] 2017 classification). 64 Moreover, they can be drug resistant.…”

“… 16 , 46 Generalized seizures mostly start without a warning sign but sometimes are preceded by severe myoclonus. 16 , 56 Also, myoclonic seizures have been described. 11 , 17 , 18 Seizures are reported to be induced by sleep deprivation, photic stimulation, stress, excitement, 16 , 37 , 47 , 62 or snow.…”