HP and holoprosencephaly: The median serum HP antibody titers (GC group/non-GC group) were 39.0/29.6 U/ml before HPE (p = 0.22), 11.0/4.97 U/ml at 0.5–2 years after HPE (p = 0.029), 7.37/3.0 U/ml at 2–5 years after HPE (p = 0.26), and 2.10/2.41 U/ml at 5–7 years after HPE (p = 0.16; Fig. 1).