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A 15-year-old girl is seen by a dermatologist for removal of multiple squamous cell carcinomas of the skin. The
patient has nearly white hair, pink irises, very pale skin, and a history of burning easily when exposed to the sun.
This patient's condition is caused by a disorder involving which of the following substances?
A. Aromatic amino acids
B. Branched chain amino acids
C. Glycolipids
D. Glycoproteins
E. Sulfur-containing amino acids
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do you have explanation, please.
thanks.
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The correct answer is A. The disease is albinism. The most common form of albinism is caused by a deficiency
of copper-dependent tyrosinase (tyrosine hydroxylase), blocking the production of melanin from the aromatic
amino acid tyrosine. Affected individuals lack melanin pigment in skin, hair, and eyes, and are prone to develop
sun-induced skin cancers, including both squamous cell carcinomas and melanomas.
Maple syrup urine disease is an example of a disorder of branched chain amino acids (choice B) causing motor
abnormalities and seizures.
Tay-Sachs disease is an example of a disorder of glycolipids (choice C). In this disorder, a deficiency of
hexosaminidase A leads to accumulation of ganglioside GM2.
Hunter's disease is an example of a disorder of glycoproteins (choice D). This mucopolysaccharidosis is
inherited as an autosomal recessive trait.
Homocystinuria disease is an example of a disorder of sulfur-containing amino acids (choice E).
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AAA=PTT
Aromatic AminoAcid are PHE, TRP, TYR
