Sunday, January 10, 2010

Lysosomal storage diseases in adults

1. Of 45 or so diseases, all are autosomal recessive except the 3 that are X linked, namely Hunter's disease (mucopolysaccharadosis type II), Fabry's, and X linked myopathy with cardiomyopathy (lysosomal associated membrane protein 2, or LAMP 2).

2. GM2 can resemble Friedrich's ataxia, but unlike Friedrich's has hyperreflexia, episodic psychosis, and absent cardiomyopathy and scoliosis which should give away the diagnosis.

3. Dementia is common, and is a presenting feature of Kuf's disease type M and adult onset MLD. Dementia is most common presenting feature of adult onset mannosidosis, fucosidosis, aspartylglucosaminuria, Niemann Pick type c (along with vertical gaze palsy, dystonia, and dysarthria)

4. Progressive myoclonic epilepsy occurs in Kufs disease type A with spike wave on EEG and photosensitivity at low flash frequencies (see Berkovic 1988 Brain for review article).  Type B is characterized by dementia, ataxia,  EPS and facial dyskinesias.  Sialodosis type I aka cherry red spot myoclonus has treatment resistant epilepsy with macular cherry red spot and abnormal neuraminidase in skin fibroblasts.

5.  Late onset myopathy occurs in Pompe's disease, with high CPK, accumulated glycogen in vesicles, and deficient alpha glucosidase which is hard to measure.  Danon disease is X linked recessive and has hypertrophic cardiomyopathy and muscle weakness, and muscle biopsy shows autophagic vacuoles with glycogen. Its due to LAMP 2 deficiency.  There is mild MR and usually, death before 30. 

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