Abnormal ERG in Duchenne Muscular Dystrophy

The diagnosis of Duchenne's Muscular Dystrophy (DMD) and Becker's Muscular Dystrophy (BMD) is based in the clinical status and evolution, the family history, serum enzymes, electromyogram and muscle biopsy. Because abnormal levels of dystrophan and cytogentic delection in the Xp21 gene may be associated with Retinitis Pigmentosa (Ref. 1-2), we studied the electroretinograms (ERG's} 23 patients, 20 of whicb. were classified as DMD and 3 as BMD. The mesopic ERG of maximum response was obtained in a Handaya electroretinograph with 5 joules stimuli and .S averages with interstimuli intervals of 3 seconds. Ninety percent the registers of the patients with DMD were abnormal (55% of the negative type with b wave under the base line, I 0% over the base line and 25% subnormal), 5% were hypernormal, and only one patient with DMD shOI'IIId a completely normal ERG. Also the b/a ratio was smaller than 1.3 in the 65% of the patients with DMD. No relations seem to exist between the ERG abnonnalities found and the time of evo tion of the disease or the presence of mental retardation. In the patients witil BMD the ERG had a normal amplitude altilough towards limit values.