Tyrosinemia type II (TYRII) is a disorder related to amino acids that leads to reduced production of an enzyme called hepatic tyrosine aminotransferase in the body. When this enzyme is lacking, a protein called tyrosine builds up, causing symptoms like eye pain and redness, painful thickening of the skin on the hands and feet, and intellectual disability.
Although there aren’t many reported cases, the available information suggests that if a pregnant mother with TYRII is not treated, it can lead to growth problems or developmental delays in the unborn baby. Managing TYRII involves adopting a low-protein diet and limiting foods containing tyrosine and phenylalanine (found in artificial sweeteners), which can help alleviate symptoms for some individuals. Starting treatment early in life seems to decrease the severity of mental impairment and improve eye and skin symptoms in some cases. Special supplements and foods designed for babies and adults with TYRII are available. Additionally, medications like oral retinoids may be beneficial in treating skin abnormalities associated with the condition.
This condition is caused by pathogenic (disease-causing) variants in the TAT gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background.
Other names for this condition are hereditary tyrosinemia, hypertyrosinemia, and tyrosinaemia.
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Revised November 2023
