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This is an MRI of the brain in a 9-year-old child

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with developmental delay.

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And on the axial T2-weighted image,

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we see several things.

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First of all,

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there's a decreased volume of the cerebral white

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matter and corresponding enlargement

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of the lateral ventricles.

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When we go from the lateral ventricles

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out towards the periphery,

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we can see there's what appears

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to be white matter here.

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And then, something that looks like gray matter.

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In between that,

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we see these little bright areas.

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This is known as the cell sparse zone

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and overlying that is cortex.

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This here is an appearance of lissencephaly with

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paucity of sulcation,

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with underlying band heterotopia.

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Now, in contrast to the first case we saw of

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lissencephaly with band type heterotopia

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in this individual here,

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we don't have band heterotopia

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in the frontal lobes,

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and we have a more normal sulcation

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pattern in the frontal lobes.

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So this is a posterior predominant involvement

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of the lissencephaly with band type heterotopia.

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And it's noted that a posterior predominant

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involvement of this disease process oftentimes

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is related to an abnormality

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in the LIS1 gene.

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So, that is the type of thing that can actually

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be put in a report to possibly

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help guide genetic testing.

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And the genetic testing has implications both

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for the patient, as well as for the family

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and for siblings.

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If I look on the sagittal image,

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we can see the parieto occipital sulcus,

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calcarine fissure, the cunius,

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very, very rudimentary sulcation.

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We're not seeing a lot of surface features,

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the lingual gyrus, very few surface features,

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the precuneus of the parietal lobe.

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Similarly, we're seeing a paucity of sulcation.

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We're seeing the overlying gray matter,

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we're seeing the cell sparse zone,

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and we're seeing this band type heterotopia.

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What I'm going to do is I'm going to show

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this on this T1-weighted image,

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and I'm going to zoom here.

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Here we can see there's a very featureless

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surface to the brain.

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Between the surface and this

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line is the gray matter.

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Subjacent to the gray matter

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is a cell sparse zone,

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and beneath that is the band type

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gray matter heterotopia.

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So, we can see there's all the features of

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lissencephaly with band type heterotopia seen here.

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We see the featureless surface,

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we see the cell sparse zone,

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we see the band-type heterotopia

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subjacent to this.

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As mentioned in this individual,

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we do not see this anteriorly.

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This was not seen anteriorly here.

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There's relative sparing.

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That posterior predominant involvement of lissencephaly

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with band-type heterotopia is often associated with

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abnormalities in the LIS1 gene.