Prenatal Diagnosis of COL4A1 Mutations in Eight Cases: Further Delineation of the Neurohistopathological Phenotype

Increasing number of mutations responsible for vascular lesions, leading to ischemic or hemorrhagic stroke in young adults, has been identified in the recent years. It has been demonstrated in both mice and humans, that mutations in COL4A1 gene promote cerebral hemorrhages. In humans, both adults and children may be affected, and the spectrum has been broadened recently to neonates and fetuses.We present a cohort of eight COL4A1 mutated fetuses in which cerebral hemorrhages were detected by ultrasound leading to elective terminations of pregnancy.Our neuropathological studies demonstrated a strikingly similar pathological pattern, dominated by supra- and infratentorial multifocal hemorrhagic lesions of various abundance and age in the vicinity of enlarged small vessels having a discontinuous wall. This was constantly associated with a spectrum of supratentorial post-ischemic damages of the grey and white matters. Morphometric studies of brain vessels confirmed vascular dilation and hypervascularization in both grey and white matters and severe attenuation of the smooth-muscle actin staining in the white matter.These observations add to the rare human neuropathological phenotype of COL4A1 mutations. Its recognition is mandatory to enhance the number of tested patients in the future, as well as the genetic counseling of parents.