Diagnostic Dilemma in an Adolescent Girl with an Eating Disorder, Intellectual Disability, and Hypomagnesemia

Abstract

Neurological disorders, including seizures, migraine, depression, and intellectual disability, are frequently associated with hypomagnesemia. Specifically, magnesium (Mg²⁺) channel transient receptor potential melastatin (TRPM) 6 and TRPM7 are essential for brain function and development. Both channels are also localized in renal and intestinal epithelia and are crucial for Mg²⁺(re)absorption. Cyclin M2 (CNNM2) is located on the basolateral side of the distal convoluted tubule. In addition, it plays a role in the maintenance of plasma Mg²⁺ levels along with TRPM6, which is present at the apical level. The <i>CNNM2</i> gene is crucial for renal magnesium handling, brain development, and neurological functioning. Here, we identified a novel mutation in the <i>CNNM2</i> gene causing a cognitive delay in a girl with hypomagnesemia. We suggest testing for CNNM2 mutation in patients with neurological impairment and hypomagnesemia.