A 2-bp deletion in exon 74 of the dystrophin gene does not clearly induce muscle weakness

Abstract

Duchenne muscular dystrophy (DMD) is caused by mutation of the dystrophin gene. Cases of dystrophinopathy with a 2-bp deletion in the dystrophin gene commonly result in DMD. We report here a case of dystrophinopathy in a 9-years-old boy with a 2-bp deletion in exon 74 of the dystrophin gene; however, the boy had no clear clinical signs of muscle weakness. Immunohistochemical studies with N-terminal (DYS3) and rod-domain anti-dystrophin (DYS1) antibodies revealed that the dystrophin signals were weaker than in the control sample (non-dystrophinopathy) at the sarcolemma of myofibers, and the studies with C-terminus anti-dystrophin antibody (DYS2) were negative. Our patient’s mutation is located between the binding sites of α-syntrophin and α-dystrobrevin. These results suggest that this mutation does not clearly induce muscle weakness at least through the age of 9 years.