Tyrosinemia, type II (TYR II) is a rare genetic condition. TYR II results from a mutation or error in a person’s DNA or genes. Due to this mistake, people with TYR II have problems breaking down certain building blocks called amino acids. TYR II occurs when the body either does not make enough or makes non-working TYR II enzyme, tyrosine aminotransferase (TAT). Enzymes are special proteins that help break down the food we eat into the pieces our body can use, for example to help make energy. If there is not enough working TAT, then the body cannot break down the amino acid tyrosine. This causes high levels of tyrosine in the liver, kidneys and central nervous system which may become toxic and cause damage. High levels of tyrosine may be detected in the blood and urine.
Most affected individuals may show signs in the first year of life, but some individuals with TYR II develop normally without any signs of the condition. TYR II tends to affect the skin and eyes, so common symptoms of this condition may include increased tear production, sensitivity to light (called photophobia), eye redness, skin lesions or cuts on the hands and feet, behavior changes, and poor coordination. If untreated, individuals are at risk developing intellectual disabilities. Seizures and behavioral problems may develop as well. Many of these complications can be prevented with early detection and lifelong management with a special diet. Many babies are screened for TYR II at birth so that treatment can begin early, however the conditions included in newborn screening differ from state to state. For more information, visit http://www.babysfirsttest.org. TYR II is an autosomal recessive trait. A genetic counselor can help you understand the genetics. Talk with your baby’s doctor and specialists to decide on the best treatment plan. Support groups are also a good source of information.