PAFAH1B1 and lissencephaly spectrum disorders: Three genes cause type1 lissencephaly: LIS1, TUBA1A, and DCX(also called doublecortin).6 LIS1 gene is located on chromosome 17p13.3 and encodes for platelet-activating factor acetylhydrolase isoform 1B which interacts with microtubule-associated proteins dynein and dynactin.