COL4A1 and polymicrogyria: Together with exome sequencing and targeted sequencing7,14, a total of seven individuals with P/LP variants in COL4A1/2 have been identified in the Australian CP Biobank (individuals tested: n = 333 individuals for COL4A2 and n = 604 for COL4A1), with a range of clinical signs, including hydrocephalus with antenatal IVH, porencephalic cysts, epileptic encephalopathy, periventricular leukomalacia, and schizencephaly with polymicrogyria and associated periventricular gliosis.