View abstract

This abstract is assigned to session AOB and FRO E-Posters

Title	Identification of CNGA3 variants in a child with a maculopathy, normal photopic ERG and near normal color vision
Abstract Nr.	3025

Purpose	To unravel the genetic diagnosis in a 9-year old child with a maculopathy.
Methods	The patient had a standard ophthalmic examination, Octopus perimetry, optical coherence tomography (OCT) scan, fundus autofluorescence (FAF) and ISCEV full-field ERG. Genetic testing consisted of analysis of a panel of retinal dystrophy genes (RetNet panel) using exome sequencing.
Results	The visual acuity was decreased: OD(S-2)=0.4,OS(S-2)=0.5. FAF showed a clear foveal lesion and perimetry showed several relative scotomas. Color vision was near normal. OCT showed a disruption of the ellipsoid zone and interruption of the outer segments. Photopic and scotopic ERG was normal, mfERG showed abnormalities, more specifically central rings. Photophobia was only seen with flash ERG. RetNet panel analysis revealed a heterozygous likely pathogenic missense variant in CNGA3: c.830 G>A p.(Arg277His). In addition, a second heterozygous missense CNGA3 variant was found of which the significance is unclear: c.811 C>G p.(Pro271Ala). Both parents were heterozygous carrier of a CNGA3 variant, demonstrating both variants occur in trans.
Conclusion	The CNGA3 genotype is a likely explanation of the phenotype observed. We expand the phenotypic spectrum of CNGA3-associated retinal dystrophies.
Conflict of interest	No

Authors 1

Last name	DE VRIES
Initials	MJ
Department	Universitair Kinderziekenhuis Koningin Fabiola
City	Brussel

Authors 2

Last name	Van Genderen
Initials	MM
Department	Bartiméus en Universitair Medisch Centrum Utrecht
City	Zeist en Utrecht

Authors 3

Last name	Postolache
Initials	L
Department	Universitair Kinderziekenhuis Koningin Fabiola
City	Brussel

Authors 4

Last name	De Baere
Initials	E
Department	Center for Medical Genetics, Ghent University and Ghent University Hospital
City	Gent