HMMR and lissencephaly spectrum disorders: Loss of Hmmr/hmmr phenotypes are reminiscent, but not overlapping with those seen for LIS1 (Lissencephaly 1), an alternate cytoplasmic dynein partner protein; classical lissencephaly, a brain developmental disease characterized by decreased cortical complexity and generally larger brain size, results from mutations in the LIS1 gene [42].