MCAD medium chain acyl-coenzyme

Table 3.1.3 Pathologic acylglycine species detected by organic acid analysis. CoA coenzyme A, FAO fatty acid oxidation, ILE isoleucine, LEU Leucine, MCAD medium-chain acyl-CoA dehydrogenase, MET methionine,...

To put the discussion described above in a practical illustration, I have included a mass spectrum from a newborn blood spot of a patient confirmed to have medium-chain acyl coenzyme A dehydrogenase (MCAD) deficiency. Figure 8.1.3 is an acylcarnitine profile obtained from a methanol extract of a dried blood spot. Stable-isotope acylcarnitine internal standards were mixed with the methanol extracting solvent at a concentration that is equivalent to 1 or 2 pmol/1 of blood. The concentrations of each internal standard are marked on the illustration by the clear hexagons. 

Fig. 8.1.3 Acylcarnitine profile of a blood spot from a newborn with medium-chain acyl coenzyme A dehydrogenase (MCAD) deficiency...

A couple has a child who has been diagnosed with medium-chain acyl coenzyme A (CoA) dehydrogenase deficiency (MCAD), a condition that allects the body s ability to metabolize medium-chain fatty acids. This couple is now expecting another child. What is the risk that this child will have MCAD ... 

The answer is d. (Murray, pp 238-249. Scriver, pp 2297-2326. Sack, pp 121—144. Wilson, pp 287-324.) Assuming that nonpaternity or an unusual method of inheritance is not operative, the parents of a child with an autosomal recessive condition are obligate heterozygotes. Therefore, their risk of having a child with medium-chain acyl-coenzyme A (CoA) dehydrogenase deficiency (MCAD) is 1/4 or 25% for each future pregnancy. 

As noted above, there have been reports that link some cases of APLP with a defect in fatty acid metabolism in the fetus. These include fetal deficiencies of long chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD), carnitine-palmitoyl transferase 1 (CPT 1), and medium chain acyl-coenzyme A dehydrogenase (MCAD). The mechanism by which defective fetal fatty acid oxidation causes maternal illness is not known. However, since the fetus uses primarily glucose metabolism for its energy needs, it is likely that toxic products from the placenta, which does use fatty acid oxidation, cause the maternal liver failure. 

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