Dysregulation of calcium metabolism in type 1 myotonic dystrophy.

One in three patients with DM1 was hypercalcaemic with unsuppressed PTH. Their clinical features and biochemical pictures resemble those of familial hypocalciuric hypercalcaemia (FHH) and raises the possibility that impaired activity of calcium-sensing receptors, due to abnormal splicing of the calcium-sensing receptor messenger RNA in DM1, causes a FHH-like syndrome ('pseudo-FHH of DM1').