Gl001580sc

Alternative names:

anencephaly sequence

Definition:

The absence of both the skull and cerebral portions of the brain.

Causes, incidence, and risk factors:

Anencephaly is a "neural tube defect" (a defect occurring early in fetal development that damages the primitive tissue which will become the brain and spinal cord). When the upper portion of the neural tube fails to close, anencephaly results, however, the specific cause is unknown. Findings suggest that it may be related to environmental toxins; however, no absolute connections have been made. Also, low plasma levels of folic acid have been implicated in contributing to neural tube defects. The incidence may reach 3.6 to 4.6 out of 10,000 births. The exact incidence is unknown, as most of these infants probably spontaneously abort. Risk factors include having a previous pregnancy with anencephaly. Nutrition is thought to play an important part in the development of neural tube defects of which anencephaly is only one. The specific nutrition risk factor is thought to be low serum levels of folic acid.