Mechanisms of mutant genes in spina bifida: a review of implications from animal models.

Spina bifida (spinal neural tube defects) has been shown to be caused by an abnormality in closure of the neural tube. Basic scientific research has rapidly progressed in experimental embryology and molecular genetics to give new insights into the pathogenesis of defective neural tube closure. The chick and the mouse have proved to be the best animal models for study because of similarities to human neurulation. The embryonic mechanisms for spina bifida appear to be under the control of mutant early regulating genes and modifying genes. Faulty early gene function in chicks and mice has been reported to result in abnormalities of neuronal and nonneuronal tissues important for neural tube closure. Research efforts are being aimed at understanding the inductive interactions and downstream target sites for early regulating genes. Elucidation of the genetic roadmap for the control of neurulation will give further insights into the causes of spina bifida.