Table 2.

Inherited Disorders to Consider in the Differential Diagnosis of ASAH1-Related Disorder: Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy (SMA-PME)

Differential DisorderGene(s)MOIClinical Features of Differential Disorder
OverlappingDistinguishing
Spinal muscular atrophy (SMA) SMN1 ARLower MND w/onset age similar to SMA IIIEarlier onset of weakness in SMA I & II; no seizures or hearing loss in SMA
Progressive myoclonus epilepsy, Lafora type EPM2
NHLRC1 		ARProgressive myoclonic seizuresNo MND in Lafora disease
Unverricht-Lundborg disease CSTB ARProgressive myoclonic jerks, tremorAtaxia & lack of MND in Unverricht-Lundborg disease
MERRF MT-TK 1mtMyoclonic epilepsy, weakness, hearing lossAtaxia, optic atrophy, & characteristic muscle biopsy (ragged red fibers) in MERRF

AR = autosomal recessive; MERRF = myoclonic epilepsy with ragged red fibers; MND = motor neuron disease; MOI = mode of inheritance; mt = mitochondrial

1.

MT-TK, a mitochondrial DNA gene, is the gene most commonly associated with MERRF. Pathogenic variants in MT-TF, MT-TL1, MT-TI, and MT-TP have also been described in a subset of individuals with MERRF.

From: ASAH1-Related Disorders

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