Hypophosphatasia (ALPL deficiency) is characterized by low bone turnover; which enzyme is deficient?

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Multiple Choice

Hypophosphatasia (ALPL deficiency) is characterized by low bone turnover; which enzyme is deficient?

Explanation:
Hypophosphatasia is due to a deficiency of alkaline phosphatase caused by ALPL gene mutations. Alkaline phosphatase in bone (the tissue-nonspecific form) is essential for mineralization because it hydrolyzes inorganic pyrophosphate, a strong inhibitor of hydroxyapatite formation. When ALP activity is low, pyrophosphate accumulates, mineralization is impaired, and bone turnover remains abnormally low. The other enzymes listed (amylase, lipase, creatine kinase) are not involved in bone mineralization or turnover, so their deficiency wouldn’t explain this condition.

Hypophosphatasia is due to a deficiency of alkaline phosphatase caused by ALPL gene mutations. Alkaline phosphatase in bone (the tissue-nonspecific form) is essential for mineralization because it hydrolyzes inorganic pyrophosphate, a strong inhibitor of hydroxyapatite formation. When ALP activity is low, pyrophosphate accumulates, mineralization is impaired, and bone turnover remains abnormally low. The other enzymes listed (amylase, lipase, creatine kinase) are not involved in bone mineralization or turnover, so their deficiency wouldn’t explain this condition.

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