During mitosis two important events happen to ensure a healthy development. The first is chromosome segregation and the second one is the orientation of cell division. Errors in chromosome segregation are related to cancer development and genetic diseases. The mitotic spindle orientation, which reflects the angle of cell division, is crucial for daughter cells fate and tissue morphology or architecture. In this project we investigated the role of two proteins; KIAA1279 and WDR62 in mitosis and especially in spindle orientation. Mutation of KIAA1279 as well as WDR62 mutation causes microcephaly and affects neural progenitors in two distinct diseases. In addition to spindle mis-orientation, depletion of KIAA1279 leads to the mitosis delay associated by mitotic spindle rotation. Loss of WDR62 increases kinetochore-microtubule stability, chromosome missegregation, aberrant number of centrosomes and spindle mis-orientation while its over-expression does not affect spindle orientation. Our findings indicate implication of KIAA1279 and WDR62 in mitosis, spindle orientation and microtubule dynamics. We study the mechanisms and consequences behind the phenotype.