Phenotypes Associated with This Genotype

Genotype
MGI:6095619

• Allelic Composition: Kif20b^magoo/Kif20b^magoo
• Genetic Background: involves: BALB/c * C57BL/6

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

mortality/aging

neonatal lethality ( J:242310 )

nervous system

abnormal axon extension ( J:242310 )

• axons retract more and pause less than control axons in cortical neurons grown in culture

disorganized cortical plate ( J:242310 )

• cortical plate appears disorganized at E15.5, with fewer neurons and less than half of them oriented properly with apical dendrites perpendicular to the pial surface

abnormal neurite morphology ( J:242310 )

• neocortical neurons exhibit fewer neurites near the soma at E18.5

• minor neurites of polarized neurons average 29% longer than controls

• both axons and minor neurites of neurons in culture are wider and increased widths correlate with looser microtubule packing

abnormal axon morphology ( J:242310 )

• branching on proximal axons appears increased among neurons at E15.5, with 5/15 neurons having at least 1 detectable branch vs. only 3/22 control neurons with one branch each

• embryonic cortical pyramidal neurons exhibit a defect in axon specification

• axons of cortical neurons are 14% shorter but have nearly twice as many collateral branches as control axons

• both axons and minor neurites of neurons in culture are wider and increased widths correlate with looser microtubule packing

• microtubule bundles have more spaces between them and there is less tubulin in the axons

abnormal dendrite morphology ( J:242310 )

• apical dendrites of neocortical neurons are about 30% shorter and have fewer terminal branches at E18.5

• E18.5 neurons apical dendrites appear thinner, with normal width at the base but tapered more quickly and are thinner than controls

• apical dendrites branch much closer to the cell body, at about 1/3 the normal distance

abnormal pyramidal neuron dendrite morphology ( J:242310 )

• pyramidal neurons have thinner apical dendrites

abnormal neuron physiology ( J:242310 )

• isolated embryonic cortical pyramidal neurons that are dissociated and then cultured, show reduced re-polarization in vitro, with only 23% of neurons polarized after 2 days in culture compared to 50% of controls and 46% being multipolar compared to 29% of controls, indicating disruption of the progression from multipolar to polarized

• marker analysis indicates that the polarization defect is not due to a shift in cell or layer fates

• neurons have longer filopodia (by about 30%) on both axons and minor neurites with increased microtubule invasion

growth/size/body

microcephaly ( J:242310 )

cellular

abnormal microtubule cytoskeleton morphology ( J:242310 )

• cortical neurons exhibit looser microtubule packing in axons and minor neurites and increased microtubule invasion in growth cone filopodia

abnormal axon extension ( J:242310 )

• axons retract more and pause less than control axons in cortical neurons grown in culture

Mouse Models of Human Disease		DO ID	OMIM ID(s)	Ref(s)
microcephaly		DOID:10907		J:242310