Tyrosinemia, type I (TYR I) is a rare, very serious genetic condition. TYR I results from a mutation or error in a person’s DNA or genes. Due to this mistake, people with TYR I have problems breaking down certain building blocks called amino acids properly. TYR I occurs when the body either does not make enough or makes non-working TYR I enzyme, fumarylacetoacetate hydrolase (FAH). Enzymes are special proteins that help break down the food we eat into the pieces our body can use for energy. If there is not enough working FAH, then the body cannot break down tyrosine. This causes high levels of tyrosine in the liver, kidneys and central nervous system, which become toxic and cause damage. High levels of tyrosine may be detected in the blood and urine.
Most babies with TYR I show signs at birth (acute form). Common symptoms of this condition may include diarrhea, bloody stool, vomiting, poor weight gain, developmental delays, tiredness, irritability, yellowing skin (jaundice), increased bleeding or bruising, swollen legs or abdomen, trouble breathing, and a “cabbage-like” smell. If untreated, babies with TYR I are at risk for life-threatening kidney and liver problems. Untreated babies with TYR I usually die before they reach 2 years old. Many of the complications can be prevented with early detection. Recommended treatment may include special diet, medication, and metabolic crisis prevention (this is important when a child is ill and unable to eat; prompt medical treatment is advised). Many babies are screened for TYR I 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 I is an autosomal recessive trait. A genetic counselor can help you understand the genetics. Talk with your baby doctor and specialists to decide on the best treatment plan. Support groups are also a good source of information.