Lissencephaly can be caused by different things. For the most part, all types of Lissencephaly fall into four different catgories of etiology(1):
The disease has been shown to be a autosomal-recessive inheritance disorder passed on from parents to children. If parents have a child with lissencephaly, they have a 25% chance of passing it on to a second child. The reoccurance rate is very low however, about 7% of children with lissencephaly have a sibling with it as well(2)
In some cases, lisencephaly is caused by a missing piece in chromosome 17. Normally the malformation is found around part 13.3 of chromosome 17. In 1993, this area was named LIS1. The protein that is encoded by chromosome 17 for this part is either partially or completely missing. Sometimes, it can actually affect a larger area on chromosome 17 then just LIS1. The LIS1 section is believed to encode the platelet-activating factor (PAF) acetylhydrolase, which is an enzyme that controls the release of a phospholipid that acts as a signaling protein to neurons. The LIS1 themselves translates these proteins. If the LIS1 is missing, then there is too many messages being sent to the neurons, and nothing to translate them(3).
*The LIS1 is marked in red*(4):
There are no known environmental causes of Lissencephaly. It doesn't, however, have to be inherited. If the baby gets an intra-uterine infection, it can get Lissencephaly. Also, if blood supply is cut off to the baby during pregnancy, Lissencephaly can develop then as well. Signs of this can be things like vaginal bleeding and calcium deposits on the brain of the baby, but most of the time is not detected because the pregnancy will still appear normal(2) .
(1)About Lissencephaly. Online. Internet. 2001, September 4. Availble: http://www.lissencephaly.org.uk/aboutliss/index.htm
(2)Dobyns, William B, MD.Lissencephaly: Information For Parents. Online. Internet. 2001, September 4. Available: http://www.lissencephaly.org/about/lissen.htm
(3)Reiner, Orly. Lissencephaly.(Development of the Cerebral Cortex, part 2). Online. Internet. 2001, September 8. Available: http://www.findarticles.com/m2250/n2_v37/20576447/p1/article.jhtml
(4)Master: Genes On Cytogenetic Map. Online. Internet. 2001, September 8. Available: http://www.ncbi.nlm.nih.gov/cgi-bin/Entrez/maps.cgi?ORG=hum&CHR=17&maps=loc-r,morbid,gene&R1=on&query=PAFAH1B1&VERBOSE=ON&ZOOM=3
