The main feature in recurrent myoglobinuria is frequent attacks of rhabdomyolysis accompanied by muscle pain and weakness, then myoglobin is excreted in the urine. These attacks are not related to exercise but they can be triggered by concomitant illnesses, such as upper respiratory tract infections. The disease usually has an early onset (less than 5 years of age) and can lead to renal failure.
Diagnosis is performed using physical examination of the muscles and biochemical tests to detect elevated plasma creatine kinase and myoglobinuria. During episodes, patients are treated with intravenous fluids and alkalinization to maintain normal plasma creatinine and urinary output. In between these episodes patients lead normal lives especially if excessive fasting is avoided.
Two families with cases of paroxysmal rhabdomyolysis were described by Ramesh and Gardner-Medwin (1992). All cases were unrelated to exercise. In one family, a 3-month-old girl had a single attack of rhabdomyolysis. Her older brother died suddenly at the age of 4 years following a day-long illness. The parents were not consanguineous. The second family had four affected girls who were born of a Kuwaiti, Bedouin, first-cousin couple. The two oldest sisters died at the age of about 5 years with acute generalized muscle weakness and myoglobinuria.
Zeharia et al. (2008) described three patients of Arab origin who developed recurrent myoglobinuria beginning at 2, 2, and 7 years of age, repsectively. Clinically, febrile episodes lasting (7-10 days) preceded myoglobinuria attacks. Patients suffered generalized weakness, inability to walk, myalgia, muscle weakness, and dark urine. All patients appeared healthy in between episodes. Zeharia et al. (2008) used homozygosity mapping to link the disorder to mutations in the LPIN1 gene.