To diagnose holoprosencephly, there are a few ways to do this. The first suspicion would come from the prenatal ultrasound that shows an alober brain. A semilobar or lobar holoprosencephaly cannot be reliably detected. Lobar can be recognized by in utero sonography. An MRI may show some abnormalities in a 30 week old fetus. When holoprosencephaly is found on an prenatal ultrasound, a high-resolution ultrasound is used to determine the presence of other anomalies.
If there is a family history of holoprosencephaly, the mother may get a genetic testing done. This may be done by extracting DNA cells from the amniocentesis at about 15 to 18 weeks of gestation. A chorionic villus sampling may be obtained by 10 to 12 weeks of gestation.
If the baby is born, a CT scan or an MRI will be used to confirm the diagnosis.
To establish the extent of the disease, there may be further evaluations to follow up on. The baby/child by have some growth deficiencies which measuring the height, weight, and the head circumference is important. Some blood work would be a thyroid function test, bone age, a complete blood count, chemistries, sedimentation rate, insulin-like growth factor 1, and insulin-like growth factor binding protein 3.
Reference
Solomon, B.D., Gropman, A., Muenke, M. (2013). Holoprosencephaly overview. Ncbi. February 14,