PTH and Hypercalcemia: The eldest sibling showed occasional mild hypercalcaemia during early childhood, a finding that settled with time and did not associate with renal impairment or disturbances in parathyroid hormone or vitamin D. The second sibling exhibited transient proteinuria and phosphaturia, although serum creatinine, glucose and electrolytes remained within reference ranges, and no persistent metabolic imbalance was documented.