Porencephaly is a rare neurological disease, typically manifest in infants,
which is characterized by the existence of degenerative cavities in the brain.
To investigate the molecular pathogenesis of porencephaly, we studied a
mouse mutant that develops porencephaly secondary to focal disruptions of
vascular basement membranes. Half of the mutant mice died with cerebral
hemorrhage within a day of birth, and È18% of survivors had porencephaly.
We show that vascular defects are caused by a semidominant mutation in the
procollagen type IV a 1 gene (Col4a1) in mice, which inhibits the secretion of
mutant and normal type IV collagen. We also show that COL4A1 mutations
segregate with porencephaly in human families. Because not all mutant mice
develop porencephaly, we propose that Col4a1 mutations conspire with
environmental trauma in causing the disease.