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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.