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Table 3 Prenatal testing of UCDs: Recommended analyses and sample requirements

From: Suggested guidelines for the diagnosis and management of urea cycle disorders

Disorder Recommended tests
NAGSD Mutation analysis using DNA from CVS or AFCa
CPS1D Mutation analysis using DNA from CVS or AFC
  Enzyme assay in late fetal liver biopsyb
OTCD Mutation analysis using DNA from CVS or AFC c
  Enzyme assay in late fetal liver biopsyb,d
ASSD Mutation analysis using DNA from CVS or AFC
  Citrulline in amniotic fluid
  Enzyme assay in intact or cultured CVS or in cultured AFC
ASLD Mutation analysis using DNA from CVS or AFC
  Argininosuccinate and its anhydrides in amniotic fluid
  Enzyme assay in intact or cultured CVS or cultured AFC
ARG1D Mutation analysis using DNA from CVS
  Enzyme assay in fetal blood erythrocytes (mid-gestation sampling)
HHH syndrome Mutation analysis using DNA from CVS or AFC
  Enzyme assay in CVS or cultured AFC
  1. First choices are given in bold-type. CVS, chorionic villus sampling. AFC, amniotic fluid cells. Grade of recommendation, D.
  2. a The woman should be informed prior to prenatal testing that in NAGSD the phenotype can be normalized completely with life-long substitutive therapy.
  3. b Very limited experience (single patient report) and test not widely available.
  4. c The presence of one mutation in a female fetus cannot predict the phenotype given the effect of lyonization.
  5. d Informative in males but interpretation not clear in females due to lyonization-caused X-mosaicism.