TABLE 3.

Simplified sum‐up of the syndromic conditions defined as PMEs. ³⁸

Name	Gene/inheritance	Seizures	Commonly associated signs	Onset age	Progression
Lafora; EPM2 (EPM2A& NHLRC1)	6p22.3 6p24.3 AR	Generalized tonic–clonic, myoclonic, and visual (frequent)	Frequently severe dementia	Late childhood, adolescence	Fast (less severe in some cases)
Unverricht‐ Lundborg: EPM1 (CSTB)	21q22.3 AR	Myoclonic, tonic–clonic (rare, often responsive to treatment)	Ataxia (variable but not severe cognitive decay)	Late childhood, adolescence	Slow, often stabilization
Sialidoses, I (NEU1)	6p21.33 AR	Myoclonic, tonic–clonic (rare)	Cherry red spots, visual loss (can be lacking), urinary sialyloligosaccharides	Second to third decades of life	Slow
Sialidoses, II (NEU1)	6p21.33 AR	Myoclonic, tonic–clonic	Dysmorphisms, hepatosplenomegaly, early cognitive impairment, ataxia	Early childhood (rarely later)	Variable, often fast
NCL AR (KCTD7)	7q11.21 AR	Myoclonic, tonic–clonic	Mental retardation, dysarthria, ataxia	Early childhood	Variable
NCL AR (CLN6)	15q23 AR	Myoclonic, tonic–clonic	Cognitive deterioration, extrapyramidal, ataxia	Adults	Intermediate
EPM1B PRICKLE1	12q12 AR	Myoclonic, tonic–clonic	Ataxia, mild mental retardation	Late childhood–adolescence	Slow
EPM4 SCARB2	4q21.1 AR	Rare (or absent) tonic–clonic	Ataxia; with or without renal failure	Adolescence‐juvenile	Fast (death at around 30 years)
EPM6 GOSR2	17q21.32 AR	Absence, or tonic–clonic (not predominant)	Ataxia, preceding myoclonus, neuropathy dementia	Early childhood	Variable
EPM7 MEAK KCNC1	11p15.1 AD	Tonic–clonic Severe myoclonus	Ataxia, mild cognitive impairment	Childhood to adolescence	Fast (wheel‐chair bound since late teen‐age)
EPM8 CERS1	19p13.11 AR	Tonic–clonic	Ataxia, other movement disorders, dementia	Early childhood	Variable (few affected)
EPM9 LMNB2	19p13.3 AR	Tonic–clonic	Cognitive delay, scoliosis, muscle atrophy	Childhood	Variable (few affected)
EPM10 PRDM8	4q21.21 AR	Undefined	Ataxia, spasticity, and cognitive decay	Childhood	Variable (few affected)
EPM11 SEMA6B	19p13.3 AR	Various types	Developmental regression	Childhood	Variable (few affected)
EPM12 SLC7A6OS	16q22.1 AR	Tonic–clonic	Ataxia, mild cognitive impairment	Juvenile	Slow (few affected)
MERRF MERRF/MELAS overlap	Various mitochondrial genes Mutations at nucleotide 8344 in most Maternal	Mostly Tonic–clonic	Ataxia, migraine, hearing loss, (short stature, pes cavus, ophthalmoparesis, myopathy)	Adolescent‐adult	Variable
FAME BAFME	Intronic TTTCA and TTTTA repeat in different loci AD	Rare (or absent) tonic–clonic	Late mild cognitive deficits or psychiatric symptoms	Adult (juvenile)	Very slow

Abbreviations: AD, autosomal dominant; AR, autosomal recessive; BAFME, Benign adult familial myoclonic epilepsy; FAME, adult familial myoclonic epilepsy; MEAK, Myoclonic epilepsy and ataxia due to KCNC1 mutation; NCL, neuronal Ceroid Lipofuscinoses.