When only including the 14 PAE participants below the clinical cutoff for microcephaly (HC ≤ 3^rd percentile, A–column 1), it is notable that 10 (~70%) of the subjects have brain volumes below the 3^rd percentile.

<p>Similarly, ~80% of the subjects with HC ≤ 10^th percentile have brain volumes under the 10^th percentile (A–column 2). Conversely, among the PAE participants with total brain volume ≤ 3^rd (n = 14, B–column 1) or 10^th percentile (n = 22, B—column 2), 55–65% of subjects have HC in the ‘normal’ range from the 11^th-99th percentiles, suggesting a disconnect between small brain volumes and head circumference. Note that the category of ≤ 10^th percentile on the x-axis of A and B includes subjects who are ≤ 3^rd percentile (to match cutoffs used in various diagnostic guidelines), while colour divisions within each bar are non-overlapping.