What Is Tyrosinemia?

Description:  Tyrosinemia is a genetic disorder, inherited in an autosomal recessive pattern, characterized by problems breaking down the amino acid tyrosine, which is a building block of most proteins. If the condition is untreated, tyrosine and its byproducts build up in tissues and organs, which can lead to serious health problems.

There are three types of tyrosinemia,distinguished by their symptoms and genetic cause.

Tyrosinemia type I: it is severe form of this disorder and usually begins in the first few months of life Affected infants do not gain weight and grow at the expected rate (failure to thrive) because eating high-protein foods leads to diarrhea and vomiting.

The characteristic features of this type include yellowing of the skin and whites of the eyes (jaundice), a cabbage-like odor, and an increased tendency to bleed (particularly nosebleeds). 

Tyrosinemia type I can lead to liver and kidney failure, softening and weakening of the bones (rickets), and an increased risk of liver cancer (hepatocellular carcinoma). 

Tyrosinemia type II: It often begins in early childhood and affects the eyes, skin, and mental development. 

The characteristic features of this type i include eye pain and redness, excessive tearing, abnormal sensitivity to light (photophobia), and thick, painful skin on the palms of the hands and soles of the feet (palmoplantar hyperkeratosis).

About half of individuals with tyrosinemia type II have some degree of intellectual disability.

Tyrosinemia type III: It is the rarest of the three types.

The characteristic features of this type include intellectual disabilities, seizures, and periodic loss of balance and coordination (intermittent ataxia)

Frequency: Worldwide, tyrosinemia type I affects about 1 in 100,000 individuals, tyrosinemia type II occurs in fewer than 1 in 250,000 individuals worldwide and tyrosinemia type III is very rare; only a few cases have been reported.