1. History
  2. Exam
  3. Photos
  4. Diagnosis
  5. Teaching Points

Case 94 Teaching Points

  • Cone dystrophy with supernormal rod electroretinogram is a unique autosomal recessive disease with diminished scotopic and photopic electroretinogram responses, but a supernormal maximal stimulation response
  • Clinically, it resembles other cone dystrophies which cause decreased visual acuity, photoaversion, and abnormal color vision
  • Caused by mutation in the KCNV2 gene which encodes a voltage-gated potassium channel subunit
  • Molecular diagnosis through genetic testing may enhance the ability to understand prognosis, clarify the possibility for other family members to be affected, and identify potential treatments for the patient


Wu H, Cowing JA, Michaelides M, et al. Mutations in the gene KCNV2 encoding a voltage-gated potassium channel subunit cause "cone dystrophy with supernormal rod electroretinogram" in humans. Am J Hum Genet 2006;79:574-579.

Heckenlively JR, Nusinowitz S. Hypoabnormal (supranormal) electroretinographic responses. In: Heckenlively JR and Arden GB, eds. Principles and Practice of Clinical Electrophysiology of Vision. Cambridge:MIT Press, 2006;533-540.

Last Modified: Tuesday, 05-Aug-2008 12:04:59 EDT