BACKGROUND: Fetuses with increased nuchal translucency but apparently normal 
karyotypes may have small genetic defects that are undetectable by conventional 
cytogenetic studies. Microarray comparative genomic hybridization (array 
comparative genomic hybridization) may help prenatal diagnosis by revealing 
small genetic defects.
CASE: A patient presented with a fetus with large nuchal translucency and 
ambiguous genitalia at 13 weeks of gestation. Conventional fetal karyotype by 
chorionic villus sampling was 46,XY,inv (1)(p31q42). The inversion was de novo. 
Further analysis by array comparative genomic hybridization revealed a 
single-copy ZEB2 gene deletion at 2q22.3 consistent with Mowat-Wilson syndrome. 
Ultrasonography at 17 weeks revealed a reduced nuchal fold of 5 mm. The patient 
decided to terminate the pregnancy, which was completed uneventfully at 17 weeks 
of gestation.
CONCLUSION: Array comparative genomic hybridization is a useful complementary 
diagnostic tool in fetuses with increased nuchal translucency but apparently 
normal karyotypes.