The purpose of this study is to look at the long term safety profile of Orfadin treatment in patients suffering from hereditary tyrosinemia type 1 (HT-1). Patients included in the study will use Orfadin according to normal clinical practice.

The planned study is a non-interventional study that will look at the long-term safety of Orfadin treatment in patients suffering from hereditary tyrosinemia type 1. Orfadin will be used according to normal practice . There is an ongoing post-marketing surveillance (PMS) program to monitor hepatic, renal, hematological, neurological and ophthalmic status in all patients treated with Orfadin. The Committee for medicinal Products for Human Use (CHMP) has required this program and have looked at the data for approximately 400 patients and found the benefit-risk ratio to be positive. The present study (PASS) will replace the ongoing PMS. The transition of countries will be gradual; starting in 2013.The study will include HT-1 patients on Orfadin treatment in standard clinical care as well as newly diagnosed patients just starting with Orfadin treatment.

Inclusion Criteria:

• All HT-1 patients receiving Orfadin treatment are eligible for entry.

Exclusion Criteria:

• No exclusion criteria

All patients receiving Orfadin is eligible for the study

Discussions ongoing with regards to data sharing/registry.