Sialidosis Type 1: Giant SSEP and Novel Mutation

Excerpt

To the Editor: A 16-y-old girl presented with progressive cerebellar ataxia, tremor and myoclonus for 2 y. She was born of non-consanguineous marriage, past and family history was normal. General examination was unremarkable. Higher mental function was normal; fundoscopic examination revealed bilateral cherry-red spot. Motor power was normal with hypertonia and exaggerated tendon reflex. Cerebellar signs were present. Routine blood and Cerebrospinal fluid (CSF) evaluation was normal. Serum thyroid peroxidase 507.4 (normal <60) U/ml was elevated with normal thyroid function. CSF IgG measles antibody was elevated 112.5 (normal <8) U/ml. Skin biopsy and duodenal biopsy was normal. Electroencephalogram (EEG) was normal; Magnetic resonance imaging (MRI) brain showed bilateral parietal cortical and mild cerebellar atrophy. Visual evoked potential (VEP) showed P100 latency bilateral prolonged and tibial Somatosensory evoked potential (SSEP) showed giant cortical potential (P38 amplitude 10.9 μV). Patient was heterozygous for known pathogenic variant c.838C > T, and heterozygous for the novel pathogenic variant g.2869A > T in exon 5 of NEU1 gene. The novel variant was predicted to be pathogenic variant. On family screening mother was heterozygous for known pathogenic variant and father for the novel variant. Six months follow-up shows no significant worsening. …