Prenatal diagnosis of a fetus with a ring chromosome 20 characterized by array-CGH.

OBJECTIVE: a fetus with a ring chromosome 20 is presented. METHODS: at 16 weeks' gestation, ultrasound examination evidenced no apparent structural malformation. Amniocentesis was performed for maternal anxiety. RESULTS: chromosome analysis identified a ring chromosome 20 and array-CGH demonstrated that the ring including micro-deletion of the short arm in 20p13, that was extended for about 632.2 kb and a micro-deletion of the long arm in 20q13.33 region. CONCLUSION: this is the first case of a ring chromosome 20 diagnosed prenatally. This reinforces the importance of offering amniocentesis with a-CGH to make more accurate prenatal diagnosis.