Exertional rhabdomyolysis in carbonic anhydrase 12 deficiency

BACKGROUND: Carbonic anhydrase 12 (CA12) deficiency, a newly recognized rare disorder, has been described among Israeli Bedouin kindred as an autosomal recessive form of isolated salt wasting in sweat, which leads to severe infantile hyponatremic dehydration, visible salt precipitation after sweating, poor feeding and slow weight gain in infancy. CASE PRESENTATION: We present two adolescents diagnosed with CA12 deficiency who developed severe rhabdomyolysis as a result of physical activity in a hot climate. CONCLUSIONS: This presentation highlights a previously unreported but significant clinical complication of this disorder and emphasizes the persistent risk of excessive salt loss via sweat and a need for certain precautions, such as increased salt intake and avoidance of prolonged and/or strenuous exercise.