We measured Concanavalin A (Con A) non-binding alphafetoprotein in amniotic fluid from 21 normal pregnancies and 20 abnormal pregnancies (complicated by anencephaly, spina bifida, or exomphalos) using small Con A-sepharose chromatography columns. There was a highly significant difference between percentage non-binding alphafetoprotein levels for pregnancies with a normal outcome (mean result 32%; range 18–47%) and pregnancies complicated by a neural tube defect or exomphalos (mean 14%; range 7–20%). The test is therefore of potential value in cases where there is uncertainty over the interpretation of total amniotic fluid alphafetoprotein levels.
References
1.
BrockDJH.Spina bifida: early antenatal diagnosis using amniotic fluid AFP heterogeneity. Br Med J1979; 2: 1402–3.
2.
KerkaertJBayardBBiserteG.Michroheterogeneity of rat, mouse and human AFP as revealed by polyacrylamide gel electrophoresis and by crossed immuno-affino-electrophoresis with different hectins. Biochim Biophys Acta1979; 576: 99–108.
3.
SmithCJKelleherPCBelangerLDallaireL.Reactivity of amniotic fluid AFP with concanavalin A in the diagnosis of neural tube defects. Br Med J1979; 1: 920–1.
4.
BrockDJH.Mechanisms by which amniotic fluid AFP may be increased in foetal abnormalities. Lancet1976; 2: 267–8.
5.
SmithCJMorrisHPKelleherConcanavalin A affinity of molecular variants of AFP in neonatal rat serum and in the serum of rats bearing hepatomas. Cancer Res.1977; 37: 2651–6.
6.
RuoslahtiEPekkalaAComingsDESeppalaM.Determination of sub-fractions of amniotic fluid AFP in diagnosing spina bifida and congenital nephrosis. Br Med J1979; 2: 768–9.
7.
Toflager-LarsenKKjaersguardEJacobsenJCNorgaard-PedersenB.Reactivity of amniotic fluid alpha-fetoprotein with concanavalin A in relation to gestational age: clinical implications. Clin Chem1980; 26: 1656–9.
