CLN3
CLN5
CLN6
CLN8
CTSD
CTSF
DNAJC5
GRN
KCTD7
MFSD8
PPT1
TPP1
| Neuronal ceroid lipofuscinoses (OMIM PS256730) | AR
(AD) 1 | A subset of lysosomal storage disorders classified into infantile, late-infantile, juvenile, & adult forms based on age of onset. All forms typically incl progressive visual deterioration, cognitive impairment, motor impairment (incl ataxia & spasticity), & myoclonic seizures w/early-onset photosensitivity on EEG, also at very low frequencies. |
| CSTB 2 | EPM1 (Unverricht-Lundborg disease) | AR | Neurodegenerative disorder characterized by onset age 6-15 yrs, stimulus-sensitive myoclonus, & tonic-clonic epileptic seizures. Some yrs after onset, ataxia, incoordination, intentional tremor, & dysarthria develop. Persons w/EPM1 may show emotional lability & depression. Seizures are usually well controlled by ASM, but myoclonic jerks are progressive, action activated, & treatment resistant. |
EPM2A
NHLRC1
|
PME, Lafora type
| AR | Focal occipital seizures presenting as transient blindness or visual hallucinations & fragmentary, symmetric, or generalized myoclonus in previously healthy persons at age 8-19 yrs. Generalized tonic-clonic seizures, atypical absence seizures, atonic seizures, & focal seizures w/impaired awareness may occur. Frequency & intractability of seizures ↑ w/disease course; status epilepticus is common. Cognitive decline becomes apparent at or soon after seizure onset. Dysarthria & ataxia appear early, spasticity later. Emotional disturbance & confusion are common in early stages & followed by dementia. |
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GOSR2
| EPM6 (OMIM 614018) | AR | Ataxia w/onset in 1st yrs of life, followed by action myoclonus & seizures later in childhood. Loss of independent walking occurs in 2nd decade. Cognition is not usually affected, but mild memory difficulties may be seen in 3rd decade. |
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KCNC1
| EPM7 (OMIM 616187) | AD | Severe progressive myoclonus & infrequent tonic-clonic seizures in 1st or 2nd decade of life. Ataxia may have early onset & most persons become wheelchair bound after adolescence; some may have cognitive deterioration. |
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KCTD7
| EPM3 (KCTD7-related PME) w/o intracellular inclusions (OMIM 611726) | AR | Characterized by the same hallmarks of PME (i.e., epilepsy, action myoclonus, progressive ataxia, & neurocognitive deterioration) as neuronal ceroid lipofuscinosis. This condition, however, is not assoc w/lysosomal storage on ultrastructural analysis of a skin biopsy. |
MT-TF
MT-TI
MT-TK
MT-TL1
MT-TP
MT-TS1
MT-TS2
|
MERRF
| Mat | Multisystem disorder characterized by myoclonus (often 1st symptom) followed by generalized epilepsy, ataxia, weakness, exercise intolerance, & dementia. Onset of symptoms may occur from childhood to adulthood, after normal early development. Common findings are ptosis, hearing loss, short stature, optic atrophy, cardiomyopathy, cardiac dysrhythmias such as Wolff-Parkinson-White syndrome, & peripheral neuropathy. |
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NEU1
| Sialidosis, types I & II (OMIM 256550) | AR | Characterized by deficiency of neuraminidase, w/2 main types: sialidosis type I usually becomes apparent in 2nd decade of life w/myoclonus, distinctive cherry-red macules, visual & gait impairments, & seizures; sialidosis type II is usually more severe, w/infanitle onset, cherry-red macules, facial dysmorphisms, skeletal malformations, & mild cognitive disability. |
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SCARB2
|
Action myoclonus – renal failure syndrome
| AR | PME & renal failure; in some instances, kidneys are not involved. Manifestations are usually evident between age 10 & 20 yrs. Neurologic manifestations (which appear before, simultaneously, or after renal manifestations) begin w/tremor at rest (exacerbated by fine motor activities) & progress to involuntary, action-activated myoclonic jerks that involve bulbar, proximal, & distal limb muscles; involuntary spontaneous myoclonic jerks; & generalized tonic-clonic seizures. Sensorimotor peripheral neuropathy & sensorineural hearing loss can be observed. 3 |
