Porphobilinogen synthase deficiency

Neonatal screening Transaminases ( ) a-Fetoprotein (+) Prothrombine time ( ) Porphobilinogen synthase deficiency +) Succinylacetone (+) Tyrosinemia type I (tyr(P) 120-1300 pmol/l)... 

Doss, M., Becker, U., Sixel, E., Geisse, S., Solcher, H., Schneider, J., 1982. Persistent proto-porphyrinemia in hereditary porphobilinogen synthase (8-aminolevulinic acid dehydrase) deficiency under low lead exposure a new molecular basis for the pathogenesis of lead intoxication. Klin. Wochenscr. 60, 599-606. 

Fig. 4.2. Increased tyrosine concentration is caused by inborn or acquired deficiency of the first two enzymes of the tyrosine degradation pathway (the increased tyrosine concentration of tyrosinemia type I is caused by secondary deficiency of 4-hydroxyphenyl-pyruvate dioxygenase). Hypertyrosinemia in the newborn is in most instances not due to inborn errors of tyrosine metabolism, but rather to liver immaturity or other unspecific liver affections. However, whenever hypertyrosinemia is found, the pathognomonic sign of tyrosinemia type I should be excluded by a sufficiently sensitive analysis of suc-cinylacetone and related metabolites. Decreased activity of porphobilinogen synthase activity in RBC is a sensitive and easily performed marker for increased concentrations of succinylacetone, which may be used as a first line diagnostic test before positive identification of succinylacetone and related metabolites by GC-MS can be achieved. It should also be noted that increased excretion of phenolic tyrosine metabolites is always found in hypertyrosinemia and is of no differential diagnostic value...

Porphobilinogen synthase (RBC) Heparinized Ambient temp, blood May be close to normal Primary deficiency... 

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