In previous studies, the allele fractions of somatic mutations in the peripheral tissues of patients with brain malformations were reported to range between 1 and 43% for PIK3CA18 and between 5 and 35% for DCX and LIS1. 19 The allele fractions of somatic mutations in blood samples ranged between 1.1 and 7.3% in our study. This evidence concerns the gene DCX and cerebral malformation.