ARG1 and microcephaly: Other clinical manifestations of ARG1‐D included developmental delay (n = 58, 36.9%), impaired mobility/gait (n = 60, 38.2%), vomiting (n = 47, 29.9%), microcephaly (n = 24, 15.2%), and somatic growth delay (n = 35, 22.2%) (Table 2).