A deficiency of the enzyme in humans can result in what is known as type II tyrosinemia, wherein there is an abundance of tyrosine as a result of tyrosine failing to undergo an aminotransferase reaction to form 4-hydroxyphenylpyruvate.
This deficiency leads to type II tyrosinemia, where there is an overproduction of tyrosine due to the enzyme's failure to catalyze the conversion of tyrosine into 4-hydroxyphenylpyruvate via a transamination reaction.