G-band and rapid FISH/QF-PCR are regarded as the gold standards for prenatal chromosomal diagnosis. Numerous microdeletion/ microduplication syndromes, however, are not detectable by conventional karyotyping. So far, we had a dilemma between fetal developmental/structural abnormalities with strong suspicion of chromosomal abnormalities and normal karyotype results. Fetal DNA chip includes more than 6,450 genetic loci and covers more than 100 common genetic diseases with numeric, structural chromosomal anomalies.

In April 2009, we launched prenatal diagnosis by fetal DNA chip of amniotic fluid samples or chorionic villi samples in the selected fetuses with sonographic abnormalities and suspicion of familial genetic disorders. We had seven cases with both abnormal ultrasound findings and pathologic copy number variations by DNA chip. In all cases, normal karyotype was confirmed by G-banding analysis.

Fetal DNA chip (array CGH) may become a strong modality to solve some part of this dilemma. Although we have to be prudent to select the patients, deal with DNA chip results and parental counseling, “sonogenetics” is one of the breakthroughs in prenatal diagnosis, and the further accumulation of case studies will be required in this new field.