Biochemical genetics deficiencies

Acylcarnitine profiles are dependent on the clinical status of the patient at the time of sample collection [56, 57]. It is therefore important to provide the biochemical genetics laboratory with information regarding the clinical context during which the sample was collected. The laboratory must be conscientious of the fact that carnitine deficiency states can be associated with acylcarnitine profiles that lack any acylcarnitine species that are elevated above the reference range. Therefore, it is essential that the complete profiles are reviewed and even borderline elevated acylcarnitines should prompt further follow up in the presence of abnormally low free acetylcar-nitine (Fig. 3.2.2). If clinically indicated, a repeat sample should be collected at least 24 h after L-carnitine supplementation. 

Mayes JS, Guthrie R (1968) Detection of heterozygotes for galactokinase deficiency in a human population. Biochem Genet 2 219-230... 

Lane AB (1985) On the nature of L-xylulose reductase deficiency in essential pentosuria. Biochem Genet 23 61-72... 

Fig. 8.3 Acylcamitine profiles with examples of a nor- (b) (Acylcanritine profiles are courtesy of the Goodman mal acylcamitine profile (a) and an acylctunitine profile Biochemical Genetics Laboratory) with elevated C14 esters suggestive of VLCAD deficiency...

M53 Murphey, W. H., Patchen, L. and Guthrie, R. Screening tests for argininosuccinic aciduria, orotic aciduria and other inherited enzyme deficiencies using dried blood specimens. Biochem. Genet., 6, 51-59 (1972)... 

B. B. Migeon, X-linked hypoxanthine-guanine phosphoribosyl transferase deficiency Detection of heterozygotes by selective medium, Biochem. Genet, 4 377 (1970). 

Robertson, D., Anderson, L, and Bachmann, M., Pigment-deficient mutants genetic, biochemical and developmental studies, in Maize Breeding and Genetics, Walden, D., Ed., John Wiley Sons, New York, 1978, 461. 

H20. Hirschhorn, R., Overview of biochemical abnormalities and molecular genetics of adenosine deaminase deficiency. Pediatr. Res. 33 (Suppl.), S35-S41 (1993). 

M5. Maekawa, M Sudo, K., Kanno, T., and Li, S. S.-L., Molecular characterization of genetic mutation in human lactate dehydrogenase-A (M) deficiency. Biochem. Biophys. Res. Commun. 168, 677-682 (1990). 

The basic genetic or biochemical defect that causes the condition (for example, alpha-1 antitrypsin deficiency)... 

The synthesis of triterpenoid saponins from the skeletons shown in Fig. 2 involves a series of further modifications that may include a variety of different oxidation and substitution events [9]. Very little is known about the enzymes and genes involved in the elaboration of the triterpenoid skeleton, although genetic and biochemical analysis of saponin-deficient mutants of plants is likely to accelerate the dissection of these processes [16]. Progress has been made in the characterisation of saponin glucosyltransferases (primarily for steroidal and steroidal alkaloid saponins), and the first of these enzymes (StSGT from potato) has been cloned. Since glycosylation at the C-3 hydroxyl position confers am-... 

In the urea cycle, two molecules of ammonia combine with a molecule of carbon dioxide to produce a molecule of urea and water. The overall cycle involves a series of biochemical reactions dependent on enzymes and carrier molecules. During the urea cycle the amino acid ornithine (C5H12N202) is produced, so the urea cycle is also called the ornithine cycle. A number of urea cycle disorders exist. These are genetic disorders that result in deficiencies in enzymes needed in one of the steps in the urea cycle. When a urea cycle deficiency occurs, ammonia cannot be eliminated from the body and death ensues. 

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