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'Cone dystrophy with supranormal rod response' in children

Arif O Khan1, May Alrashed, Fowzan S Alkuraya

  • 1Division of Pediatric Ophthalmology, King Khaled Eye Specialist Hospital, Riyadh 11462, Saudi Arabia. arif.khan@mssm.edu

The British Journal of Ophthalmology
|September 9, 2011
PubMed

Insights

Children with KCNV2 mutations present with varied symptoms, often including abnormal head movements and nystagmus that improve over time. Electroretinography (ERG) findings are key to diagnosing this cone dystrophy.

Area of Science:

  • Ophthalmology and Genetics
  • Pediatric Neurology and Vision Science

Background:

  • Cone dystrophy with supranormal rod response is a distinct retinal disorder associated with recessive KCNV2 mutations.
  • Understanding the initial clinical presentation is crucial for early diagnosis and management of this rare condition.

Observation:

  • A retrospective case series identified nine children from seven families, initially examined between 2 and 8 years of age.
  • Presentations varied, including abnormal head position with head shaking and nystagmus, infantile nystagmus, suspected congenital glaucoma, and refractive errors.
  • Clinical retinal changes and myopia were infrequent at initial examination.

Findings:

  • Electroretinography (ERG) revealed characteristic delayed scotopic responses with supranormal, high normal, or normal scotopic b-wave responses to bright flash.
  • KCNV2 gene sequencing identified homozygous recessive mutations in all patients, including two novel mutations.
  • The common initial presentation of abnormal head position, head shaking, and nystagmus showed improvement or resolution over time.

Implications:

  • The diverse initial clinical presentations highlight the importance of considering KCNV2-related retinal disorders in children with unexplained visual symptoms.
  • Characteristic ERG findings, particularly the scotopic b-wave response, are specific indicators for KCNV2 mutations.
  • Early identification and genetic testing can facilitate appropriate management and genetic counseling for affected families.
Abstract

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