Step I FA OXIDATION DISEASES

[tasar1898]

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Hey guys could someone explain this to me?? Its a question from Kaplan qbank

Kid with hypoglycemia/hypoketonemia has cardiomegaly/muscle aches/etc and dies at 5year old . Labs at an exam showed elevated carnitine esters in serum AND muscle tissue

The answers were some glycogen storage and 1)Carnitine Uptake Deficiency
2) LCAD Deficiency and I chose Carnitine since if Cat-1 makes the carnitine esters and there is no uptake of them in the mitochondrion they should accumulate... But it was LCAD deficiency and in the explanation they say ''Since Carnitine-esters are accumulating in serum and in muscle tissue , a carnitine uptake deficiency is ruled out'' !! Why is that??And also , shouldnt LCAD deficiency cause accumulation of simple FA's (not ''carnitized'' )

In my mind FA oxidation should be like this FA in cytoplasm --> CAT-1 makes FA-CARN --> Uptake by carnitine transporter ( DEFECT SHOULD BE HERE IN CARNITINE UPTAKE deficiency , so FA-CARN accumulates..) --> FA-CARN in mitochondrion --> CAT-2 removes carnitine and makes FA ---> FA gets oxidized

I hope someone could clear this out for me coz its driving me nuts

Thanks a lot

 

[Jabbed]

Carnitine uptake deficiency = a deficiency in carnitine. It is NOT a deficiency in the uptake of fatty acid-carnitine esters.

↓LCAD activity → ↑FA in mitochondria → ↑FA-carnitine esters d/t oversaturation of CAT II

 

[tasar1898]

Oh I see it was a naming issue , now i completely understand---> MCAD/VLCAD = Carnitine esters in serum , Carnitine deficiency = FA's in serum/muscle tissue . Thanks a lot man !!