A newborn has black pigmentation around the ears and eyes and black urine. This is indicative of which metabolic disorder?

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Multiple Choice

A newborn has black pigmentation around the ears and eyes and black urine. This is indicative of which metabolic disorder?

This finding points to an inborn error of tyrosine metabolism. When homogentisic acid oxidase is deficient, homogentisic acid builds up and deposits as a dark pigment in connective tissues (ochronosis), and urine darkens on standing due to oxidation. The combination of black pigmentation around the ears and eyes and dark urine in a newborn is classic for alkaptonuria. The other options don’t fit: phenylketonuria doesn’t cause dark urine or ear/eye pigmentation; albinism is a systemic lack of pigment in skin and eyes without dark urine; melanoma is a cancer, not a congenital metabolic disorder.

This finding points to an inborn error of tyrosine metabolism. When homogentisic acid oxidase is deficient, homogentisic acid builds up and deposits as a dark pigment in connective tissues (ochronosis), and urine darkens on standing due to oxidation. The combination of black pigmentation around the ears and eyes and dark urine in a newborn is classic for alkaptonuria. The other options don’t fit: phenylketonuria doesn’t cause dark urine or ear/eye pigmentation; albinism is a systemic lack of pigment in skin and eyes without dark urine; melanoma is a cancer, not a congenital metabolic disorder.

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