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  #1  
Old 05-04-2011
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Star Prep question neuro # 01

A 7 month old infant was brought to the doctor by her parents because of seizures. The girl also had progressive blindness and diminished response over the past 5 months. On examination, fundoscopy of eye shows retinal pallor except macula. Abdominal examn- no findings. Which of the following enzyme could be deficient in the infant?

A. Alpha galactosidase
B. Aryl sulfatase A
C. Glucocerbrosidase
D. Hexosaminidase A
E. Sphingomyelinase.
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Old 05-04-2011
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Lysosomal Storage Disease? I really want to say Hexosaminidase A, but for some reason I would go with Sphingomyelinase.
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Old 05-04-2011
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I think may be hexosaminidase A (Tay-Sachs disease)

a-galactosidase A(Fabry dis)-peripheral neuropathy,angiokeratomes,renal insufficiency
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Old 05-04-2011
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In Tay Sacks cherry red spots are seen on the macula.So it may be the cause of absence of palour on macula.
therefore i think it may be D hexosaminidase A
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Old 05-05-2011
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yeah i think tay sachs so hexosaminidase a. also since there are no abdominal findings which if hepto/spleno megaly would have made it into neimen picks which is sphingomyelinase. another cherry red macula one is sandhoff jacobs which is hexosaminidase a and b and progresses more rapidly than tay sachs...I think atleast.
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Old 05-05-2011
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I agree Tay Sachs

the answer is Hexosaminidase. Both Tay Sachs and Neimann picks disease can produce neurological symptoms and cherry red spots on macula but Tay Sachs has no hepatosplenomegaly whereas Neimann Pick does. FA 2010 page 111
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Old 05-05-2011
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Correct Answer

Alpha glactacid I guess it coz glactacyid is for vision
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Old 05-05-2011
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In addition to all what you said retrospectively,,, i think the psychmotor retardation goes more with tay sachs and that had been noted in the stem by "seizures and the normal respnse,s declining" + the age usually less than 1 yeas old,,
Good luck
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Old 05-05-2011
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Correct Answer Tay Sach's : Hexosaminidase A

Yes, as most of u all got it right, Hexosaminidase A def is the right answer.

Tay Sach's is a AR, hexosaminidase deficiency causing accumulation of GM2 ganglioside in neurons. Infants are normal at birth but then begin to suffer diminished responsiveness, blindness, loss of neurologic fn, seizures. Ophthalmic examn shows retinal pallor with sparing of macula ( cherry red spots) No hepato or splenomgaly seen.

Niemann Pick is caused by sphingomyelinase def which causes accumulation of sphingomyelin in cns and reticulo-endothelial system. Hence hepatosplenomagaly, cherry red spots and neurological signs of progressive motor weakeness and mental manifestations seen.

Metachromatic leukodystrophy, def of aryl sulfatase A, causing accumulation of sulfatides. Late infantile onset, motor symptoms( cns deterioration with progressive tetraplegia and decerebrate state), peripheral neuropathy occur.

Fabry's disease, XR, def of alpha galatosidase A, ceramide trihexoside accumulates. Corneal changes, angiokeratomas, heart, renal and GI manifestations seen.

Gaucher's disease def of glucocerbrosidase causing glucocerbrosides accumaulation. Hepatomegaly, splenomagaly, bone marrow involvement causing bone pain, fracture and deformities seen.
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Tay-Sachs,

Cherry red spot
is found in both Tay-Sachs and Niemann-Pick but NP is more of a reticuloendothelial problem with the characteristic foamy macrophages whereas TS presentation is mostly CNS.
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