PCR and immunoblot analyses of dystrophin in Becker muscular dystrophy.
The dystrophin gene was examined by PCR analysis in 30 Japanese patients with Becker muscular dystrophy (BMD). Fifteen PCR of these patients had exon deletion, generally, less than three exons. Muscle biopsies were also performed in 20 BMD patients (10 with sequence deletions, and 10 without detectable sequence deletions) in order to correlate PCR findings with immunoblot and immunostaining data. A patchy, heterogeneous membrane immunostaining pattern of reduced intensity was found, irrespective of the presence or absence of deletions. Immunoblotting studies demonstrated dystrophin of low molecular mass and quantity in BMD patients with deletion mutations, while a low quantity of dystrophin with an apparent wild type molecular mass was observed in nearly half the BMD patients without detectable deletions. However, these dystrophins were also found to have slightly abnormal molecular masses when the standard electrophoresis time was prolonged. This suggests that immunoblots and PCR data correlate well in patients with BMD. Additionally, it is suggested that immunoblot assays can detect abnormalities in dystrophin in the absence of detectable PCR deletions.