An 8-year-old child has bilateral corneal ulcers, photophobia, and painful hyperkeratotic plaques on the palms and soles. Plasma tyrosine is markedly elevated. Which enzyme deficiency is responsible?

• A Homogentisate oxidase
• B Fumarylacetoacetate hydrolase
• C p-Hydroxyphenylpyruvate dioxygenase
• D Tyrosine aminotransferase ✓

Explanation

Tyrosinemia type II (Richner-Hanhart syndrome) results from hepatic tyrosine aminotransferase deficiency. Elevated tyrosine crystallizes in corneal epithelium causing painful keratitis and ulceration, and causes palmoplantar keratosis plus intellectual disability. Fumarylacetoacetate hydrolase deficiency defines type I with liver failure, p-hydroxyphenylpyruvate dioxygenase deficiency gives type III with neurologic disease, and homogentisate oxidase deficiency causes alkaptonuria without keratitis.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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