Prenatal Diagnosis Of Propionic Acidemia Research Articles

Biochemical and genetic approaches to the prenatal diagnosis of propionic acidemia in 78 pregnancies

BackgroundPropionic acidemia (PA) is a serious metabolic disorder, and different approaches have been applied to its prenatal diagnosis. To evaluate the reliability and validity of a biochemical strategy in the prenatal diagnosis of PA, we conducted a retrospective study of our 11-year experiences at a single center.MethodsWe accumulated data from 78 pregnancies from 58 families referred to our center and provided prenatal diagnosis by directed genetic analysis and/or metabolite measurement using tandem mass spectrometry (MS/MS) and gas chromatography/mass spectrometry (GC/MS) of amniotic fluid (AF) samples.ResultsSixty-five unaffected fetuses (83.33%) and 13 affected fetuses (16.67%) were confirmed in our study. The characteristic metabolites including propionylcarnitine (C3) level, C3/acetylcarnitine (C2) ratio and 2-methylcitric acid (2MCA) level in unaffected and affected groups showed significant differences (P < 0.0001), while the level of 3-hydroxypropionic acid (3HPA) showed no significant difference between the two groups (P > 0.05).Of the 78 pregnancies, 24 fetuses were found to have either one causative pathogenic variant or were without genetic information in the proband. Three of these fetuses had elevated AF levels of C3, C3/C2 ratio, and 2MCA and, thus, were determined to be affected, while the remaining fetuses were determined to be unaffected based on a normal AF metabolite profile. Our genetic and biochemical results were highly consistent with postnatal follow-up results on all unaffected fetuses.ConclusionsWe conclude that a biochemical approach can serve as a fast and convenient prenatal diagnostic method for pregnancies at an increased risk for PA, which could be used in conjunction with genetic testing for precise prenatal diagnosis of this disorder. In our analysis, the characteristic metabolites C3 level, C3/C2 ratio, and 2MCA level in AF supernatant were dependable biochemical markers for diagnosis, of which the C3/C2 ratio appears to be the most reliable biochemical marker for the prenatal diagnosis of PA.

Prenatal diagnosis of propionic acidemia by measuring methylcitric acid in dried amniotic fluid on filter paper using GC/MS

Propionic acidemia is a frequent inborn error of metabolism. Methylcitric acid, a key indicator of propionic acidemia, increases in the amniotic fluid of affected fetuses. For prenatal diagnosis, the methylcitric acid in amniotic fluid can be measured by stable-isotope dilution GC/MS. Here, we quantified this indicator in samples of amniotic fluid that had been dried on filter paper and transported at ambient temperatures, and compared the results with data obtained from the original amniotic fluid. We then used the filter-paper method to screen at-risk fetuses and obtained a clear-cut diagnosis in each case.

Prenatal diagnosis of propionic acidemia

In this report we summarize our experience in prenatal diagnosis of propionic acidemia (PA) since 1987. Overall, we have investigated 25 pregnancies at risk from 19 unrelated families. Until genetic structure of the genes involved in PA was elucidated, prenatal diagnosis has been successfully performed by means of metabolite quantitation and/or enzymatic assays in foetal issue. Today, direct propionyl-CoA carboxylase activity assay in combination with molecular analysis in chorion villi can be regarded as a fast and reliable method of choice for prenatal diagnosis of this organic acidemia.

Rapid and sensitive method for prenatal diagnosis of propionic acidemia using stable isotope dilution gas chromatography–mass spectrometry and urease pretreatment

Propionic acidemia is one of the most frequent inborn errors of metabolism caused by a deficiency of propionyl-CoA carboxylase. Methylcitric acid, a key indicator of this disorder, is increased in amniotic fluid when a fetus is affected. Therefore, the direct chemical analysis of cell-free amniotic fluid for methylcitric acid, using stable isotope dilution gas chromatography–mass spectrometry, was carried out for the prenatal diagnosis of propionic acidemia. We developed a simple, highly sensitive, and accurate method for quantitation of this polar methylcitric acid in amniotic fluids by applying a simplified urease pretreatment which we devised earlier for urine. As the recovery of methylcitric acid from amniotic fluid was as high as 91% with a coefficient of variation lower than 3% in this procedure, only 0.02 ml of sample was required for the analysis of the affected fetus. This new procedure takes 1 h for sample pretreatment, including derivatization, and 15 min for GC–MS measurement and provides final results within 1.5 h.

Prenatal diagnosis of organic acidemias based on amniotic fluid levels of acylcarnitines.

Acylcarnitines in amniotic fluid samples were analyzed for the prenatal diagnosis of propionic acidemia, methylmalonic aciduria, isovaleric acidemia, and glutaric aciduria by electrospray tandem mass spectrometry. Although the levels of the specific acylcarnitine between affected and unaffected cases showed an overlap, the ratios of propionylcarnitine to 4-carbon acylcarnitine levels for propionic acidemia and methylmalonic aciduria, those of isovalerylcarnitine to propionylcarnitine for isovaleric acidemia, and those of glutarylcarnitine to propionylcarnitine for glutaric aciduria type I were shown to be reliable indicators in the prenatal diagnosis. In addition, it is suggested that the combination of the ratios of glutarylcarnitine, isovaleryl-carnitine, and hexanoylcarnitine to propionylcarnitine may be useful for the prenatal diagnosis of glutaric aciduria type II.

Acylcarnitines in amniotic fluid: application to the prenatal diagnosis of propionic acidaemia.

Acylcarnitines were assayed in amniotic fluid by isotope dilution tandem mass spectrometry. Control values for propionylcarnitine, C4 and C5 acylcarnitines were established. Propionylcarnitine was elevated by a factor of 5 relative to controls in the amniotic fluid of three pregnancies affected with propionic acidaemia. This may provide a convenient new method for prenatal diagnosis of propionic acidaemia. One pregnancy at risk for propionic acidaemia but unaffected according to methylcitrate analysis had an intermediate level of propionylcarnitine, indicating the need for further studies to determine the range of concentration in probable heterozygotes.

Early prenatal diagnosis of propionic acidaemia with simultaneous sampling of chorionic villus and amniotic fluid

Early prenatal diagnosis of propionic acidaemia with simultaneous sampling of chorionic villus and amniotic fluid

Prenatal Diagnosis of Propionic and Methylmalonic Acidaemia by Stable Isotope Dilution Analysis of Amniotic Fluid

Stable isotope dilution gas chromatography—mass spectrometry (GC/MS) analysis of methylcitric acid in amniotic fluid for the rapid and accurate prenatal diagnosis of propionic acidaemia (McKusick 23200) and methylmalonic acidaemia (McKusick 25100) was first described in 1980 (Naylor et al., 1980). This was soon followed by similar methods for the determination of methylmalonic acid in amniotic fluid for prenatal diagnosis of methylmalonic acidaemia (Trefz et al.,1981; Zinn et al., 1982; Sweetman et al.,1982). We describe here our results for the prenatal diagnosis of 102 pregnancies at risk for either propionic acidaemia or methylmalonic acidaemia.

Successful First Trimester Diagnosis in a Pregnancy at Risk for Propionic Acidaemia

Propionic acidaemia is an inborn error of amino acid metabolism caused by a deficiency of propionyl-CoA carboxylase (PCC) (EC 6.4.1.3). PCC activity has been demonstrated in several tissues including fibroblasts, amniotic fluid cells and chorionic villi (Sweetman et al., 1986). Prenatal diagnosis of propionic acidaemia can be performed by the determination of the methylcitrate level in amniotic fluid (Naylor et al., 1980), by studies of incorporation of [1-14C]propionate into protein of amniocytes (Willard et al., 1976) and by direct assay of PCC activity in cultured amniotic fluid cells (Gompertz et al., 1975) or in intact chorionic villi (Chadefaux et al., 1988). We report a successful first trimester diagnosis by direct PCC assay in uncultured chorionic villi in a pregnancy at risk for propionic acidaemia.

Methylcitrate in maternal urine during a pregnancy with a fetus affected with propionic acidaemia

Patients homozygous for propionic acidaemia have high levels of methylcitric acid in urine while heterozygotes have normal levels. Methylcitric acid was determined by stable isotope dilution gas chromatography-mass spectrometry in maternal urine during a pregnancy with a fetus affected with propionic acidaemia. Although the levels increased linearly between 23 and 39 weeks of gestation, the levels were not significantly elevated above normal until after 30 weeks of gestation. Thus, determination of methylcitric acid in maternal urine is not of value for early prenatal diagnosis of propionic acidaemia.

Pitfalls in the prenatal diagnosis of propionic acidemia

Prenatal diagnosis of propionic acidemia can be performed by two independent methods: measuring an elevated quantity of the metabolite methylcitrate in amniotic fluid; and demonstrating deficient activity of propionyl-CoA carboxylase in amniocytes cultured from the fluid. Discordant results in a pregnancy at risk for propionic acidemia were obtained. Elevated concentration of methylcitrate indicated an affected fetus, but the activity of propionyl-CoA carboxylase was normal. An affected female infant was born. Chromosome variant analysis demonstrated that between passage two and four overgrowth of the female fetal cells by contaminating maternal cells led to the "false negative" results obtained by enzyme assay. This experience demonstrates the value of analysis of abnormal metabolites in amniotic fluid and highlights a problem that could confound the prenatal diagnosis of any condition assessed by enzyme activity.

Prenatal diagnosis of propionic acidemia

Prenatal diagnosis of propionic acidemia

Prenatal Diagnosis of Propionic Acidemia

Prenatal diagnosis of a fetus with propionic acidemia has been accomplished by the detection of methylcitrate, a unique metabolite, in the amniotic fluid by liquid partition chromatography and gas chromatography-mass spectrometry. The diagnosis was confirmed by demonstration of deficient activity of propionyl-CoA carboxylase in cells cultured from the amniotic fluid and in fetal tissues. In two subsequent pregnancies, methylcitrate was not present in amniotic fluid. Enzyme assay indicated that one fetus was heterozygous and the other was normal, and healthy infants were born at term. The analysis of organic acids in amniotic fluid permits very rapid prenatal diagnosis, usually within 48 hours after obtaining the fluid. It may provide a general method in conditions in which an unusual metabolite can be identified.