[Four family members with proximal myotonic myopathy]

Abstract

A 41-year-old woman had a 15-year history of pain in her thighs and arms, which also became weaker, and a decrease in visual acuity. Her 35-year-old brother, their 38-year-old sister and their 64-year-old mother also had myalgia, myotonia and proximal muscle weakness, and the women also had cataracts. Additional examinations and tests led to a diagnosis of proximal myotonic myopathy (PROMM) in all four cases. Neurological and ophthalmological follow-up was provided on a yearly basis, including ECG. The clinical features of PROMM display similarities to the adult form of myotonic dystrophy (MD) but differ in the proximal localisation of the muscle weakness and the frequent occurrence of pain in the affected muscles. PROMM is an autosomal dominant hereditary multisystemic disorder with a less serious course than MD and is rarely accompanied by cognitive disorders. In most cases, a genetic defect on chromosome 3q21 is the cause of the disease. A probable diagnosis can be made on the basis of the clinical symptoms and the results of simple laboratory tests, and can be confirmed via DNA analysis. As yet, the disorder can only be treated symptomatically, preferably via a multidisciplinary approach by a neurologist, an ophthalmologist, a cardiologist and a rehabilitation specialist.