Hereditary optic neuropathies (HON)

Carried by: SENSGENE

References:

Clinician(s): Catherine VIGNAL-CLERMONT (Hôpital Fondation Rothschild) and Vasily SMIRNOV (CHU de Lille), Matthieu ROBERT (APHP Necker)

Biologist(s): Patrizia BONNEAU (CHU d’Angers)

Presentation

Rare ocular diseases responsible for the degeneration of the retinal ganglion cells and their axons, forming the optic nerve
Cause of visual impairment (from mild VA loss to blindness) and including syndromic forms
Variable patterns of transmission involving the nuclear and mitochondrial genomes.
The two most common HONs: Leber Hereditary Optic Neuropathy (LHON) and dominant optic atrophy (Kjer’s disease)
Growing number of candidate genes

Confirmed diagnosis of HON (adult and pediatric patients):
- Clinical: bilateral loss of central visual function (visual acuity, visual field, macular OCT, pRNFL and CGL, colour vision tests if available)
- Family history and pedigree (mandatory)
- Rule out differential diagnoses (retinal disorders) and other non-hereditary optic neuropathies. Electrophysiology testing encouraged (VEP, pERG) and brain/orbit MRI is mandatory for simplex cases
- No gene defect identified after testing mitochondrial DNA and a panel of nuclear genes involved in HON

E-prescription should be accompanied by:

Ophthalmologist’s report and the following items:
- Fundus (colour fundus pictures)
- Autofluorescence images
- OCT (pRNFL, CGL, macular slab)
- Visual field
- brain MRI (report and informative images)
- Colour vision tests: Ishihara, 15 Hue if possible
Visual Electrophysiology tests: electroretinogram (ERG) and visual evoked potentials (VEP)
A specific template listing/presenting these various tests to fill and to upload onto the submission platform is available here