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Chapter 42: Iron and Copper Metabolism

A 3-month-old infant is brought to the doctor by distraught parents who indicate that they feel there is something seriously wrong with the child. The baby is not thriving, demonstrates clear neurodegenerative deficit, and has a cherubic face with sagging jowls and no eyebrows. The infant's hair is gray and has the appearance and feel of steel wool. This constellation of symptoms is associated with which of the following disorders?

A. acute intermittent porphyria (AIP)

B. hemochromatosis type 1

C. Menkes disease

D. porphyria cutanea tarda (PCT)

E. Wilson disease

Answer C: Menkes disease is inherited as an X-linked disorder of copper homeostasis. The disorder is associated with an inability to absorb copper from the gastrointestinal tract. As a consequence of the reduced delivery of copper to the brain, Menkes patients exhibit severe mental and developmental impairment. In addition, because there is a need for copper as a cofactor in numerous enzymes (eg, lysyl oxidases) Menkes patients also exhibit connective tissue abnormalities. Menkes disease is the result of defects in the P-type ATPase protein that is responsible for the translocation of copper across the intestinal basal-lateral membrane into the blood, thus allowing for uptake of dietary copper. This protein is encoded by the ATPase, Cu2+-transporting, α-polypeptide (ATP7A) gene.

A 3-month-old infant who otherwise appeared normal during the first 2 months of life except for a bout of hyperbilirubinemia is now clearly exhibiting developmental delay. In addition, the infant's hair has become grayish and dull and there is a stubble of broken hair over the occiput and temporal regions. The facial appearance has also changed such that the infant has very pudgy cheeks, abnormal eyebrows, and sagging jowls. The occurrence of frequent convulsions was the stimulus for the parents to bring their child to the emergency room. These rapidly deteriorating symptoms are indicative of which of the following disorders?

A. Crigler-Najjar syndrome type I

B. Gilbert syndrome

C. hemochromatosis

D. Menkes disease

E. Refsum disease

Answer D: Menkes disease is inherited as an X-linked disorder of copper homeostasis. The disorder is associated with an inability to absorb copper from the gastrointestinal tract. As a consequence of the reduced delivery of copper to the brain, Menkes patients exhibit severe mental and developmental impairment. In addition, because there is a need for copper as a cofactor in numerous enzymes (eg, lysyl oxidases) Menkes patients also ...

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