Holoprosencephaly (HPE) 2 is a brain developmental abnormality in which the left and right halves of the brain don’t divide correctly. HPE also causes facial defects with a wide range of severity. Examples of extreme facial defects include cyclopia (one central eye), complete lack of eyes, or proboscis (tubular nasal structure above the eyes); milder facial defects include close-set eyes, cleft lip, flattened nose, having only one nostril. Intellectual disability, seizures, instability of temperature/heart rate, and pituitary problems are also symptoms of HPE.
HPE can be inherited, though not all people with an HPE-causing genetic mutation will develop it. HPE2 occurs with a mutation in gene SIX3. HPE is difficult to diagnose, as it is rare. However, it is first suspected if the baby’s head is unusually small prenatally. Molecular testing is available to detect HPE-related genetic mutations; additionally, magnetic resonance imaging (MRI) or computerized tomography (CT) scans are often performed to confirm diagnosis with a picture of the child’s brain. In severe cases of HPE, facial malformations may be enough to diagnose after birth and may even be diagnosed before birth with an ultrasound.
There is no specific treatment or cure for HPE -- most newborns diagnosed with HPE do not live past 6 months of age. However, a large portion of those with mild HPE live past 12 months and may have normal life expectancies depending on the related medical issues present. In those cases, any symptomatic medical issues may be treated individually. Facial or cleft lip and palate reconstructive surgeries are also options if appropriate. If you or a family member has been diagnosed with holoprosencephaly 2, speak with your doctor about the most current treatment options. Support groups may also be available for further resources and information.
Description Last Updated: Jul 27, 2018