CPS1 and ornithine carbamoyltransferase deficiency: The majority of patients in the exposed population had an OTC deficiency (72.2%; 35 females (7 with neonatal and 28 with late onset presentation), 22 males (9 with neonatal and 13 with late onset presentation); 19% (5 females, 10 males) had a CPS1 deficiency, and only small numbers had a NAGS (5.1%; 2 females, 2 males) or ORNT1 (3.8%; 2 females, 1 male) deficiency.