Study of ORGN001 (Formerly ALXN1101) in Neonates, Infants and Children With Molybdenum Cofactor Deficiency (MOCD) Type A

Patients must meet all of the following inclusion criteria to be considered for enrollment in this study: 1. Male or female neonatal patient (1 to 28 days of age \[inclusive\] at the time of ORGN001 administration, with day 1 of age corresponding to the day of birth) or infant (29 days to \<2 years of age) or child (2 to 5 years of age \[inclusive\]) with MoCD Type A, previously untreated with ORGN001 or treated with ORGN001 through Compassionate Use/Individual Named Patient access 2. In neonates, diagnosis of MoCD Type A, based on: Prenatal genetic diagnosis, or Onset of clinical and/or laboratory signs and symptoms consistent with MoCD Type A (eg, seizures, exaggerated startle response, high-pitched cry, axial hypotonia, limb hypertonia, feeding difficulties, elevated urinary sulfite and/or SSC, elevated xanthine in urine or blood, or low or absent uric acid in the urine or blood) within the first 28 days after birth 3. In infants or children, diagnosis of MoCD Type A, based on: Confirmed genetic diagnosis (genetic confirmation of the diagnosis of MoCD Type A may be obtained after initiation of ORGN001 therapy in certain cases), biochemical profile, and clinical presentation consistent with MoCD Type A 4. Parent or legal guardian must have signed the informed consent form (ICF) prior to any study procedures being performed Patients will be excluded from participating in the study if they meet any of the following criteria: 1. Diagnosis other than MoCD Type A (may be determined after the initiation of study drug) 2. Condition that is considered by the treating physician to be a contraindication to therapy, including evidence of abnormalities on brain imaging not attributable to MoCD Type A, or that might otherwise interfere with the patient's participation in the study, pose any additional risk for the patient, or confound patient assessments 3. Antenatal and/or postnatal brain imaging prior to initiation of treatment with ORGN001 that indicates cortical or subcortical cystic encephalomalacia, clinically significant intracranial hemorrhage, or other abnormalities on brain imaging determined by the treating physician to be clinically significant 4. Modified Glasgow Coma Scale (mGCS) for Infants and Children score of less than 7 for more than 24 hours (does not apply to children less than 1 day in age).