The true frequency (occurrence) of chiari malformation is not known. Studies estimating the proportion of the population with chiari malformation have reported inconsistent numbers. Some studies estimate that 1 out of 1,000 individuals have a chiari malformation, while others estimate the frequency might be as high as 1 out of 200. Complicating this estimation is the fact that some individuals with chiari malformation do not experience symptoms until adulthood, if at all.
Last updated: 9/13/2016
Are chiari malformations genetic?
While the exact cause of chiari malformation remains unknown, genes are thought to play a role in the development of chiari malformation type 1. There are a number of inheritable syndromes (a group of characteristics and/or symptoms that occur together in a recognizable pattern) that are associated with chiari malformation type 1, such as Klippel-Feil syndrome, hypophosphatemic rickets, renal coloboma syndrome. There are also several families that have been reported in the medical literature in which more than one family member has what appears to be an isolated chiari 1 malformation, not associated with an identified syndrome. Increasing evidence suggests that in some families, there are strong genetic contributors to the development of chiari malformation type 1. Researchers continue to search for the gene(s) that are responsible for causing the chiari malformation.
There is a research study entitled Genetic Analysis of Chiari I Malformation sponsored by the National Institute of Neurological Disorders and Stroke (NINDS) at the US National Institutes of Health that is currently recruiting participants to better understand the genetic factors related to chiari I malformation and discover the location of the genes responsible for the malformation. Click on the research study link to learn more about this study.
Last updated: 9/14/2016
We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please
Speer M.C, Gorege T.M, Enterline D.S., Franklin A., Wolpert C., Milhorate T.H.. A genetic hypothesis for Chiari 1 Malformation with or without syringomyelia. Neurosurg Focus. March 15, 2000; 8(3):E12. http://www.ncbi.nlm.nih.gov/pubmed/16676924.