Brain development and the genetics
of brain development
Gary D. Clark, MD
Departments of Pediatrics, Neurology, and Neuroscience, Cain Foundation Laboratories,
6621 Fannin Street, MC 3-6365, Houston, TX 77030-2399, USA
The brain is a seemingly nonsegmented organ that is, however, formed in
a segmented fashion by the overlap of genes that define anatomic and prob-
ably functional components of the brain. Other genes and their encoded
proteins regulate the processes of cell proliferation and migration; many
of these genes have been identified based upon discoveries of human and
mouse disease-causing genes.
Human brain developmental disorders represent clinical challenges for
the diagnosing clinician as well as for the treating physician. Some disorders
represent well-defined clinical and genetic entities for which there are specific
tests; others have ill-defined genetic causes, while others can have both
genetic and destructive causes. In most cases the recognition of a disorder
of brain development portends certain developmental disabilities and often
seizure disorders that can be very difficult to treat. In addition, it now bears
upon the treating physician to recognize the genetic causes, and to properly
advise patients and their families of the risks of recurrence or refer them to
the proper specialist who can do so. The genetics of some of these disorders
are not all well defined at present, and the recognition of some disorders is
variable; what is known is presented herein.
The genetics and signaling utilized in brain development is briefly
reviewed to provide the framework for the understanding of human brain
developmental disorders. The well-defined genetic disorders of brain devel-
opment are discussed, and a brief suggested algorithm for evaluation and for
counseling of patients is provided.
