Transient bradycardia in a mouse model for the oromandibulofacial limb hypogenesis syndrome following chorionic villus sampling.

Amniotic sac puncture carried out on day 13 mouse embryos induces a high incidence of craniofacial and limb abnormalities that resemble the anomalies seen in the oromandibulofacial limb hypogenesis syndrome occasionally encountered following chorionic villus sampling carried out during early human pregnancy. It has been hypothesized that this syndrome probably has a vascular basis, possibly due to hypotension and hypoperfusion of tissues secondary to placental trauma, though no detailed aetiology has so far been described. We have determined embryonic heart rates in control embryos, in embryos at intervals following anaesthesia, and following amniotic sac puncture. An increased duration of bradycardia is seen following this procedure which is not observed in anaesthetic-only controls and in embryos in the contralateral (non-operated) uterine horns. We discuss why the incidence of oromandibulofacial limb hypogenesis syndrome is low following chorionic villus sampling, and propose a possible aetiology for the limb abnormalities seen in this condition.