Table 1.

Characteristics of FCD lesion subtypes. The table summarises the histological, genetic and radiological features reported to characterise lesion types.

Lesion subtype	Histology	Genetics	Radiological features
FCD I (A&B)	FCD IA: radial cortical dyslamination (Blumcke et al., 2011) FCD IB: tangential cortical dyslamination (Blumcke et al., 2011)	•Variants in DEPDC5 (Baulac et al., 2015) •FCD IB: chromosomal rearrangement in AKT3 (Conti et al., 2015)	•Cortical thinning •Grey/white matter blurring •Signal abnormalities on T1w/T2w imaging •Lobar hypoplasia (Blumcke et al., 2011, Kabat and Król, 2012, Kim et al., 2012, Krsek et al., 2008)
FCD IIA	Dysmorphic neurons (Blumcke et al., 2011)	•Variants in NPRL3 (Sim et al., 2016) •Variants in DEPDC5 (Mirzaa et al., 2016) •Variants of TSC2 (Majores et al., 2005) •Mutations of mTOR (Lim et al., 2015, Mirzaa et al., 2016) •Mutation in PI3KCA (Jansen et al., 2015)	•Cortical thickening •Grey/white matter blurring •Signal abnormalities on T1w/T2w imaging •Abnormal gyrification (Kabat and Król, 2012, Krsek et al., 2008)
FCD IIB	Dysmorphic neurons and balloon cells (Blumcke et al., 2011)	•Variants of TSC1 (Becker et al., 2002) •Mutations of mTOR (Lim et al., 2015, Mirzaa et al., 2016) •Variant in exon 8 of PTEN (Weiskopf et al., 2013)	•Cortical thickening •Grey/white matter blurring •Signal abnormalities on T1w/T2w imaging •Transmantle sign •Abnormal gyrification (Kim et al., 2012, Mühlebner et al., 2011) (Barkovich et al., 1997)