ERG phenotype of a dystrophin mutation in heterozygous female carriers of Duchenne muscular dystrophy
- Kathleen M Fitzgeralda,d,
- Gerhard W Cibisa,b,e,
- Ann Headrick Gettelc,
- Robert Rinaldic,
- David J Harrisd,
- Robert A Whited
- aThe Children’s Mercy Hospital Vision Sciences Laboratory, 2401 Gillham Road, Kansas City, MO 64108, USA, bSection of Ophthalmology, The Children’s Mercy Hospital, Kansas City, MO, USA, cSection of Rehabilitation Medicine, The Children’s Mercy Hospital, Kansas City, MO, USA, dSection of Genetics, The Children’s Mercy Hospital, Kansas City, MO, USA, eThe Eye Foundation of Kansas City, University of Missouri School of Medicine, Kansas City, MO, USA
- Dr Fitzgerald.
- Received 24 June 1998
- Revised 24 August 1998
Abstract
PURPOSE Mutations in the dystrophin gene result in Duchenne muscular dystrophy (DMD). DMD is associated with an abnormal electroretinogram (ERG) if the mutation disrupts the translation of retinal dystrophin (Dp260). Our aim was to determine if incomplete ERG abnormalities would be associated with heterozygous carriers of dystrophin gene mutations.
METHODS Ganzfeld ERGs were obtained under scotopic and photopic testing conditions from a family which includes the heterozygous maternal grandmother, the heterozygous mother, and her children, two affected boys and dizygotic twin sibs, an unaffected male and heterozygous female. Southern blot analyses were done to characterise the dystrophin mutation.
RESULTS The dystrophin gene was found to contain a deletion encompassing exon 50. The ERGs in the two affected boys were abnormal, consistent with the DMD ERG phenotype. Serial ERGs of the heterozygous females were abnormal; however, they were less severely affected than the DMD boys. The ERG of the female sib showed a greater abnormality than her mother and maternal grandmother. The unaffected twin had a normal ERG.
CONCLUSIONS The ERG shows abnormalities associated with carrier status in this family with a single exon deletion. A large study of confirmed obligate carriers is planned to clarify further the value of the ERG in detecting female heterozygous carriers of dystrophin gene mutations.
