Porencephaly (POREN) is an autosomal dominant disorder characterized by fluid-filled cysts and cavities in the brain. Clinical finding include hemiplegia, tetraparesis, limb dystonia, seizures, developmental delay, exotropia and visual field defects. Neuroimaging findings include diffuse leukoencephalopathy, microbleeds, and deep white matter hyperintensities. POREN1 (MIM 175780) and POREN2 (MIM 614483) are caused by mutations in the COL4A1 and COL4A2 genes, respectively. They code for collagen alpha-1(IV) and alpha-2 (IV) chains.
COL4A1 mutations can also cause two other autosomal dominant disorders, brain small vessel disease with or without ocular anomalies (BSVD; MIM 607595) and angiopathy, hereditary, with nephropathy, aneurysms, and muscle cramps (HANAC; MIM 611773). BSVD findings consist of migraine, hemiparesis, central facial palsy, seizures, porencephaly, and intellectual disability. Eye findings may include retinal arteriolar tortuosity, hypopigmentation of the fundus, corneal opacities, iris hypoplasia, microphthalmia, microcornea, cataract, glaucoma, astigmatism, amblyopia, myopia, and hyperopia. HANAC is characterized by retinal arteriolar tortuosity, retinal hemorrhage, hematuria, renal cysts, mild renal failure, and muscle contractures. Imaging show that the cerebrovascular phenotype in HANAC includes both small vessel disease and large vessel disease, but with a low incidence of hemorrhagic stroke compared to the other COL4A1 related disorders, POREN1 and BSVD.

Copy number variation (CNV) analysis of the porencephaly genes using high density targeted (HDT) array is also offered as a panel. Additionally, CTGT offers a comprehensive test (both NGS panel and HDT array panel) for these genes. Panel genes are also offered as individual sequencing and deletion/duplication tests, unless otherwise indicated.
The porencephaly NGS panel consists of two genes: COL4A1 and COL4A2.