Macrocephaly (i.e., head circumference ≥2 SD above the mean) occurred more frequently in individuals with PI3K/AKT pathway gene mutations; all 17 had macrocephaly, compared with 140/200 individuals with OGID due to epigenetic regulation gene mutations (p = 4.1 × 10−3; Figure 4A). This evidence concerns the gene PIK3CA and Macrocephaly.