Duchenne muscular dystrophy: negative electroretinograms and normal dark adaptation. Reappraisal of assignment of X linked incomplete congenital stationary night blindness.

Aland Island eye disease (AIED) and X linked congenital stationary night blindness (CSNB) have been mapped to Xp11.3. Patients have been described with deletions of the Duchenne muscular dystrophy (DMD) gene who also had a negative electroretinogram (ERG) similar to that seen in patients with CSNB and AIED. This seems to confirm that some cases of AIED and CSNB map to Xp21. We examined 16 boys with DMD/BMD (Becker muscular dystrophy) of whom 10 had negative ERGs, eight of them having deletions downstream from exon 44. Normal dark adaptation thresholds were observed in all patients and there were no anomalous visual functions. Hence, CSNB cannot be assigned to Xp21 and negative ERG in DMD/BMD is not associated with eye disease. Six boys with DMD/BMD had normal ERGs. We speculate that a retinal or glial dystrophin may be truncated or absent in the boys with negative ERGs.