• ↓ Alkaline phosphatase

Etiology: AR – hereditary deficiency of alkaline phosphatase

Clinical: 4 subtypes

1. Congenital type (present at birth): 75 % mortality
2. Early infantile type (appears within 1st 6 months of life): 50 % mortality. It causes:
   • Renal calcinosis
   • Cranial synostosis
   • Delayed motor development
   • Premature teeth loss
3. Late infantile type (appears within 6 – 24 months of life): few skeletal defects limited to irregular ossification, some rickets-like changes and premature teeth loss.
4. Adult type (rare!!!): bone pain, pathological fractures, childhood history of rickets.

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