The natural history of cognitive dysfunction in late onset GM2 gangliosidosis
Posted Jul 07 2008 7:13pm
Frey LC, Ringel SP, Filley CM. Arch Neurol 2005;62:989-994
Comment-- As one my mentors warned, pediatric diseases show up in adults and we need to diagnose them. This is the "adult form" of Tay Sachs disease. Late onset GM2 gangliosidosis (LGG)has late onset (adolescents and young adults), has a prolonged disease course, comparably late onset of neurologic dysfunction, and affects a significant minority of patients who are not of Ashkenazi Jewish descent.
Case one was a 46 year old Ahkenazi Jewish woman who had required special tutoring and was "emotionally immature." She showed emotional lability, aggressiveness and visual hallucinations. She had dysarthria, poor recall on memory tests, muscle atrophy and fasciculations, appendicular ataxia, and dysmetria, diffusely brisk reflexes and upgoing toes. EMG/ muscle biopsy done at age 13 showed diffuse denervation. She had a FSIQ of 93 at age 10, and 70 at age 20. CT showed cerebellar atrophy. Hex A level at age 20 showed partial deficiency (20.3 % residual WBC hex A).
Case 2 was sister of case one. She was learning disabled, weakness and ataxia, multiple psychiatric hospitalizations for psychoses, responsive to phenothiazines and lithium. She had partial hex A deficiency (20 %). She had supranuclear gaze palsy, tongue fasciculations, diffuse weakness, brisk reflexes, and flexor plantar responses. She had abnormal executive function, as detailed in Trailmaking Tests A and B and memory.
Case 3 was a 30 yo woman who had come to attention with deteriorating schoolwork in second grade. At age 25 she had a confusional state and profound abulia. She was briefly given AED's. MMSE was 27/30. She had limited upgaze, mild neck flexor weakness, diffuse limb weakness, brisk reflexes with bilateral Babinski signs, mild CT atrophy, slow RAM's, EMG showed abnormal spontaneous activity and decreased motor unit amplitude.
Review of 62 patients-- 2/3 were Ashknenazi Jews, 82 % LMN signs, and 69 % cerebellar signs, were seen. Mean hex A ranged from 0-48 %. 44 % were described as having cognitive dysfunction. 38 % of patients were cognitively stable, and 62 % had progressive cognitive loss.