A Collection of Case Studies in Infants With UCD to Evaluate Infant Growth and the Safety of a New Medical Food for UCD

Inclusion criteria: Prospective study: * Male and female infants diagnosed with UCD, aged from birth to 30 days of age * Parent / primary caregiver is able to give informed consent * Infants who will receive and will be able to take study medical food as part (40-70%) of their protein requirements in the day Retrospective study: * Male and female term infants diagnosed with UCD, that started UCD Anamix Infant when aged from birth to 30 days of age. * Parent / primary caregiver is able to give informed consent * Infants who received UCD Anamix Infant as part of their protein requirements (40-70%) in the day for at least 16 weeks. Exclusion Criteria: * Infants \< 5lb 8oz (\< 2.5 kg) at birth * Infants \<34 weeks of gestation and using a special premature formula at study start * Infants with severe concurrent illness or major congenital malformations, except conditions consequent to urea cycle disorder * Infants with suspected or documented systemic or congenital infections (e.g. human immunodeficiency virus) * Infants with evidence of significant cardiac, respiratory, haematological, gastrointestinal, or other systemic diseases * Infants currently taking cytotoxic drugs * Investigator's uncertainty about the willingness or ability of the parent to comply with the protocol requirements * Participation in any other study involving investigational products concomitantly or prior to entry into the study * An infant of any personnel connected with the study * Infants whose parent / primary caregiver is younger than the legal age of consent