I am so very sorry for the loss of your baby girl. I hope that this information is helpful to you.
As you have learned, Agnathia, also called otocephaly, is a rare syndrome characterized by microstomia (small mouth), aglossia (absence of the tongue), agnathia (absence of the lower jaw), and ear abnormalities. The estimated prevalence is 1 in 70,000. Most babies who have this condition do not survive. Polyhydramnios is frequently found with agnathia. Both genetic and environmental factors have an impact on this condition. Most reported cases have been sporadic, but a couple of familial cases have been reported. I am not aware of any clinical trials for this condition or any genetic testing. The diagnosis can sometimes be made on ultrasound but can be difficult.
It may help to meet with a genetic counselor to who will take a detailed a family history, discuss the diagnosis and the impact on future pregnancies. You can locate a genetic counselor near you using the National Society of Genetic Counselor’s website. More information about agnathia is available from The Genetic and Rare Diseases Information Center at 888-205-2311.