Pachygyria, also called "incomplete lissencephaly," may be caused by various non-genetic (environmental) and genetic factors that play a role in impairing the development of the outer region of the brain (the cerebral cortex). The cerebral cortex is responsible for conscious movement and thought, and should have deep convolutions (gyri) and grooves (sulci), which are formed by "infolding" of the cerebral cortex. During normal embryonic growth, immature cells that later develop into specialized nerve cells (neurons) normally migrate to the brain's surface, making several layers of cells. When this process is impaired, the cells don't migrate to their locations, resulting in too few cell layers and absence (agyria) or incomplete development (pachygyria) of gyri.
Environmental factors that contribute to the condition may include intrauterine infection during pregnancy (such as a virus), and insufficient flow of oxygenated blood to the brain (ischemia) during fetal development.
More than 25 syndromes due to abnormal migration of neurons have been reported; in some of these cases, the genetic cause and pattern of inheritance depends on that of the specific syndrome.
Mutations in several genes have been identified in people with abnormalities of cortical development, including the KIF5C, KIF2A, DYNC1H1, WDR62, and TUBG1 genes. Studies have also found that isolated lissencephaly may result from mutations in the LIS1and XLIS (also called DCX) genes.
People interested in learning about the cause of pachygyria in themselves or family members should speak with their health care provider or a a genetics professional.
Last updated: 2/20/2014
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