European Journal of Pediatrics

, Volume 157, Supplement 2, pp S88–S93 | Cite as

Post- and prenatal diagnostic methods for the homocystinurias

  • B. Fowler
  • C. Jakobs

Abstract

Diagnosis of the homozygous homocystinurias can be performed by investigations at the metabolite, enzyme and DNA level. The existence of variant forms due to the wide range of genetic variation may result in only small differences in various parameters between controls and affected subjects.

1. Sulphur amino acid concentrations in plasma, especially total homocysteine, are useful in first line diagnostic investigations.

2. Cystathionine-β-synthase (CBS), methylenetetrahydrofolate reductase (MTHFR) and methylfolate homocysteine methyltransferase (MFMT) can be directly assayed in many tissues including fibroblasts (each) and blood cells (except CBS). Indirect whole cell assays which measure pathway activity dependent on a particular enzyme can provide useful diagnostic information.

3. Direct analysis of mutations is available for CBS, MTHFR and recently also for MFMT deficiencies. However the existence of a larger number of very rare, often private, mutations limits the usefulness of this approach in routine diagnosis.

The above diagnostic approaches can generally be applied to prenatal diagnosis. Measurement of methylmalonic acid and other metabolites in amniotic fluid by stable isotope dilution / gas chromatography-mass spectrometry is well established for the methylmalonic acidurias. This method has also been applied to combined homocystinuria/methylmalonic aciduria supported by enzyme assays in cultured cells. Total homocysteine measurement in cell free amniotic fluid is also possible, performed so far in 14 cases with two affected fetuses. The indirect assay of methionine formation from [14C] labelled formate in intact cultured amniotic fluid cells has been for prenatal diagnosis of the remethylation defects.

Key words Homocystinuria Prenatal Diagnosis Enzyme Metabolite 

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • B. Fowler
    • 1
  • C. Jakobs
    • 2
  1. 1.University Children’s Hospital, Römergasse 8, CH-4005 Basel, Switzerland, Tel.: 41 61 691 2626, Fax: 41 61 692 6555CH
  2. 2.Department of Clinical Chemistry and Paediatrics, Free University Hospital, Amsterdam, The NetherlandsNL

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