the presence of these atypical features in patients whose lower motor neuron involvement would otherwise be consistent with juvenile-onset spinal muscular atrophy should raise the suspicion of the presence of hexosaminidase-a deficiency and gm2 gangliosidosis that can be proved by appropriate enzyme assays .
C0039373
hexosaminidase-a deficiency
C0268274
gm2 gangliosidosis