Tubulin Isotype		TUBA1A	TUBB2B	TUBB3 (a)	TUBB3 (b)
Number of reported mutations		25 missense	5 missense	6 missense	8 missense
Phenotypic Spectrum	Clinical Disorder	Severe LIS to MCD	PMG	MCD	Axon gudiance disorder, CFEOM3
	Intellectual and Social Disability	Generally severe	Generally severe	Mild to severe	Normal to moderate, mutation dependent
	Head Circumference	Most microcephalic	Microcephalic	<3% to 50%	Generally normal, mutation dependent
	Epilepsy	Can be present	Can be present	Can be present	Absent
	Strabismus	Comitant to absent	Not indicated	Comitant to absent	Incomitant (CFEOM3) to rarely absent, mutation dependent
	Degenerative peripheral neuropathy	No	No	No	Yes, mutation dependent
Fetopsy and/or MRI neuroimaging data	Published fetopsy	Yes	Yes	Yes	No
	Cortex	Complete Agyria to Mild Gyral Malformation	Bilateral to Assymetric Polymicrogyria	Lissencephaly to Gyral Disorganization	Generally normal
	Major Cortical Location	Diffuse, Posterior, Perisylvian, or Frontal	Frontal, Parietal, and Temporal lobes	Perisylvian to Frontoparietal	NA
	Corpus Callosum	Agenesis to mild dysgenesis, Probst bundles reported	Agenesis to mild dysgenesis	Agenesis to normal	Agenesis to normal; Probst bundles reported
	Evidence of primary axon guidance defect	Possibly	No	Yes	Yes
	Basal Ganglia appearance	Dysmorphic to normal	Dysmorphic to normal	Dysmorphic to normal	Dysmorphic to normal
	Cerebellum	Vermis > generalized hypoplasia, occasionally normal	Vermis > generalized hypoplasia	Vermis > generalized hypoplasia	Mild dysplasia to normal
	Gross Brainstem appearance	Hypoplasia to normal	Hypoplasia to normal	Hypoplasia to Normal	Normal

LIS = Lissencephaly; MCD = Malformations of Cortical Development; PMG = Polymicrogyria; CFEOM3 = Congenital Fibrosis of the Extraocular Muscle type 3