HYC2 is an extreme congenital communicating hydrocephalus, i.e., an excessive accumulation of cerebrospinal fluid (CSF) in the brain caused by blockage of CSF flow after exiting the ventricles. This accumulation causes macrocephaly, seizures, decreased IQ, and brain malformations such as thinning of the cerebral cortex and a simplified gyration pattern. As a congenital disorder, HYC2 has an onset in utero and can often result in still births. Prognosis of the disorder depends on early diagnosis and treatment.
The disorder can be diagnosed by clinical neurological evaluations and by imaging techniques such as ultrasonography, CT, MRI, or pressure-monitoring techniques. Treatment involves the surgical placement of a ventriculoperitoneal shunt that diverts the flow of CSF, allowing it to be absorbed as part of the normal circulatory process.