EARLY SIGNS
There are three types of tyrosinemia (I, II, and III). Tyrosinemia, type I (TYR I) is the most severe of the three forms. Signs of TYR I usually begin in the first few months of life, though some individuals do not begin showing signs until childhood.
Babies with TYR I may show signs such as:
- Diarrhea
- Bloody stool
- Vomiting
- Poor weight gain
- Sleeping longer and more often
- Tiredness
- Irritability
- “Cabbage-like” odor
- Yellowing skin (known as jaundice)
- Increased bleeding or bruising
- Swollen legs or abdomen
- Developmental delays
- Trouble breathing
Many of these signs may occur when your baby eats foods that his or her body cannot break down. They can be triggered by long periods of time without eating, illnesses, and infections.
CAUSES
When we eat food, enzymes help break it down. Some enzymes help break down proteins into their building blocks, called amino acids. Other enzymes break down these amino acids. In tyrosinemia, type I (TYR I), the enzyme fumarylacetoacetate hydrolase (FAH) is not working correctly.
FAH’s job is to break down the amino acid tyrosine. Babies with TYR I do not make enough FAH. When there is a shortage in FAH, the body cannot break down tyrosine. Tyrosine builds up in the body, which can be toxic.
TYR I is an autosomal recessive genetic condition. This means that a child must inherit two copies of the non-working gene for TYR I, one from each parent, in order to have the condition. The parents of a child with an autosomal recessive condition each carry one copy of the non-working gene, but they typically do not show signs and symptoms of the condition. While having a child with TYR I is rare, when both parents are carriers, they can have more than one child with the condition.
TREATMENT
Dietary Treatment
Your baby may need to be on a restricted diet to avoid proteins that his or her body cannot break down. A dietician or nutritionist can help you plan the appropriate diet for your child.
Your baby’s doctor might also recommend special formulas and foods for children with tyrosinemia, type I (TYR I). These formulas will likely need to be continued through adulthood.
Supplements and Medications
Your doctor may prescribe a medication called nitisinone (also called Orfadin or NTBC). This medication helps stop TYR I from affecting the brain, liver, and kidneys. It is important to screen for TYR I at birth because taking this medication early can prevent liver, kidney, and brain damage.
If TYR I is affecting your baby’s bones, your doctor might also prescribe vitamin D supplements. Vitamin D is a natural substance that can help strengthen bones.
EXPECTED OUTCOMES
Early treatment can prevent many of the liver, kidney, and brain effects of tyrosinemia, type I (TYR I). Children who receive treatment can have healthy growth and development.
If treatment is not started soon after birth, children risk some liver and kidney damage.
Without treatment, children are at risk for life-threatening kidney and liver problems.