Figure 2.

Posterior-Predominant (P > A) LIS with Subcortical Ribbon Heterotopia Associated with Bi-allelic APC2 Mutations

Individual identifier along left. Midline sagittal MRIs showed P > A LIS with a stretched and thinned corpus callosum and relatively well-preserved anterior folding, brainstem, and cerebellar architecture. Axial images all showed P > A LIS with mild (B–D, N–P, and R–T) or moderate (F–H and J–L) frontal pachygyria and posterior agyria (asterisks shown in fourth column only). 5-II-1: short, comma-shaped subcortical heterotopias began just posterior to and at the same level as the tail of the caudate nuclei (between the red arrows in [B and C]). 7-III-3 and 7-III-4: same subcortical heterotopia began in the same place, but then merged with the deep cellular layer of the posterior agyria (thin red arrows in O, R, and S). 6-III-1 and 6-III-2 (and in [R]): this same region appeared to have dysplastic cortex extending from the pial surface to the ventricular surface, with no white matter apparent (two-headed arrows in [F], [G], [J], [K], and [N]). The ribbon heterotopia began at this level (two-headed arrow in [K]). All subjects showed striking dysplastic in-folding of one or several gyri in the mesial occipital region (thick blue or red arrows in all five images in second column). The selected images include T1-weighted (A–D and M–T) and T2-weighted (E–L) images in the midline sagittal (first column) and multiple axial planes progressed from low to high slices (second to fourth columns).