The cell-type distribution pattern varied across patients, for example, PIK3CA-mutated hemimegalencephaly cases with high mosaicism showed mutation enrichment in glial cells (astrocytes and oligodendrocytes), whereas MTOR-mutated FCDII cases with low mosaicism showed predominant neuronal and astrocytic distribution (Extended Data Fig. 4b,c and Supplementary Table 8). Here, PIK3CA is linked to hemimegalencephaly.