Abstract
Argininoiuccinic acid (ASA) lyase deficiency, the basic defect in ASAuria, can be studied in cultured skin fibroblasts and cultured amniotic fluid (AF) cells. We diagnosed a fetus affected with ASAuria, after studying the obligate heterozygote parents and an affected child. The affected child had been thought to excrete cystathionine, which we showed to be an ASA anhydride. An increased ASA cone was found in AF from amniocenteses at 14, 15 and 17 weeks (fetus at risk = 0.3 μmoles/ml, norm i=0). ASA lyase activity in cultured AF cells from the fetus at risk, as measured by the ratio of 14C-cltrulline/3H leucine uptake into TCA-precipitable protein, was 0.4% of that in normal AF cells. The pregnancy was terminated, and the in utero diagnosis was confirmed by analysis of fetal liver for ASA lyase (1.8% of normal). It was demonstrated also that all 8 fetal tissues studied. Including brain, had significant accumulations of ASA (normal=0). These findings: demonstrate the possible pitfalls in the diagnosis of ASAuria by urinary amino acid analysis; confirm earlier suggestions that ASAuria may be diagnosed by determining ASA levels in amniotic fluid; cast doubt upon the value of “early” neonatal dietary therapy with arginine, as it appears that the enzymatic defect is already producing an accumulation of unmetabolized substrate in fetal tissues by the beginning of the second trimester; and provide evidence that the urea cycle is active prenatally.
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Fleisher, L., Rassin, D., Rogers, P. et al. ARGININOSUCCINIC ACIDURIA: PRENATAL DIAGNOSIS AND STUDIES OF AN AFFECTED FETUS. Pediatr Res 11, 455 (1977). https://doi.org/10.1203/00006450-197704000-00511
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DOI: https://doi.org/10.1203/00006450-197704000-00511