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Tay Sachs disease - Coggle Diagram
Tay Sachs disease
pathogenesis
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without degradation, GM2 gangliosides accumulate in lysosomes of CNS and peripheral neurones
HEX A heterodimer 1 alpha + 1 beta subunit (genes: HEXA, HEXB)
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clinical phenotypes
acute infantile TSD
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Decreased attentiveness, unusual eye movements
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Generalized muscular hypotonia with sustained ankle clonus and hyperreflexia, myoclonic jerks
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Progressive macrocephaly with proportionate ventricular enlargement on neuroimaging beginning at age 18 months
onset before 6 mo, rapid progression, death <5 y
developmental plateau 6-10 mo, progressive loss of skills, vision deteriorates, decererebrate posturing, difficulty swallowing, woresning seizures, vegetative state
subacute juvenile TSD
A period of normal development until ages two to five years followed by a plateauing of skills and then loss of previously acquired developmental skills
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Progressive dysarthria, drooling, and eventually absent speech
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later onset, survival until late childhood/adolescense
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late-onset TSD
Onset of symptoms in teens or adulthood, variable phenotypes
Progressive neurogenic weakness of antigravity muscles in the lower extremities and frequent falls, years later triceps weakness
Dysarthria, tremor, and incoordination, progressive dystonia
Acute psychiatric manifestations including psychosis (which can be the initial manifestation of disease) - can be initial manifestation!
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diagnosis
absent/low HEX A acitivity - serum, leukocyte, other tissue
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Toro C, Shirvan L, Tifft C. HEXA Disorders. 1999 Mar 11 [Updated 2020 Oct 1]. In: Adam MP, Mirzaa GM, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2023. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1218/
beta-hexosaminidase A deficiency, HEXA disorder