Tyrosinemia is clinically classified into acute and chronic forms according to the age of onset. Acute tyrosinemia develops within the first 6 months of life, with vomiting, diarrhea, weight gain, hepatomegaly, jaundice, ascites, hemorrhage, hypoglycemia, and edema being more common. The chronic form of tyrosinemia is relatively stable and has a milder clinical presentation. When acute type tyrosinemia is present, it can be very damaging to a person’s body. Tests required by the patient clinically: Enzymatic analysis: Patients with tyrosinemia type I have low or absent FAH activity. Tyrosinemia can be diagnosed by measuring the activity of the enzyme yohimbine acetoacetate hydrolase in liver biopsies, fibroblasts or peripheral blood lymphocytes. Genetic testing: The causative gene for tyrosinemia type I, FAH, is located on human chromosome 15q23-25, and more than 40 mutations have been detected, the most common of which is IVS12+5 (G>A), which can account for 90% of patients in certain regions such as Canada; another common mutation, IVS6-1 (G>T), has been found in patients in southern Europe, Morocco and Turkey. There are other types of mutations that are more common in patients of certain ethnicities, such as W262X in Finns, D233V in Turks, P261L in German Jews, and Q64H in Pakistani patients, respectively. These mutations are mostly single base mutations, such as missense mutations, nonsense mutations, or clip point mutations, and small fragment deletions and insertions in the enzyme yohimbine acetoacetate hydrolase gene have also been reported; a large fragment deletion in the enzyme yohimbine acetoacetate hydrolase gene was reported in one patient.