Clinical phenotype and genotype analysis of a family with autosomal dominant optic atrophy caused by a novel nonsense variant in OPA1

Objective  To analyze the clinical phenotype and the associated pathogenic genes in a family exhibiting autosomal dominant inherited optic atrophy (ADOA).

Methods  A pedigree analysis was conducted on a Han Chinese family with ADOA comprising two generations and four individuals from Henan Province.The family with two ADOA patients was recruited at Henan Eye Hospital between July and October 2023.Detailed medical histories were collected for the proband and family members.Comprehensive ophthalmologic evaluations were performed, including assessments of visual acuity, visual field, fundus photography, electroretinogram (ERG), visual evoked potential (VEP), and optical coherence tomography.Additionally, hearing, electromyography, and magnetic resonance imaging were performed on the proband to assess the presence of systemic symptoms.Peripheral blood samples were collected from four family members, and whole exome sequencing (WES) was performed on the proband, with subsequent validation via Sanger sequencing for the other family members.The pathogenicity and protein struture of the novel variant were analyzed.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Henan Eye Hospital (No.HNEECKY-2019[15]).Written informed consent was obtained from each subject.

Results  The proband was a 15-year-old female with a 4-year history of vision loss in the left eye and optic atrophy, mild thinning of central macular foveal thickness, locally mild thinning of ganglion cell complex layer thickness, low VEP amplitude, and partial visual field defects in both eyes, and no significant hearing impairment or dystonia on systemic examination.The proband’s mother had partial optic nerve atrophy and slightly decreased central macular foveal thickness in both eyes, and mild ERG abnormalities, but no significant VEP abnormalities.WES identified a heterozygous nonsense variant c. 676C>T (p.Gln226Ter) in exon 6 of the OPA1 gene of the proband and her mother.This variant has not been previously reported in the literature, nor is it listed in the Human Gene Mutation Database, the Thousand Genomes Project, or the Genome Aggregation Database, which results in a premature termination codon at glutamine position 226.Protein structure analysis showed that p. Gln226Ter of the OPA1 protein induces alterations in the hydrogen bonding of the protein binding to surrounding residues, which in turn leads to protein function alterations.The variant was classified as potentially pathogenic according to the ACMG standards and guidelines.

Conclusions  Patients in this ADOA family present with adolescent-onset optic atrophy in both eyes, with a predominance in the left eye.The c. 676C>T variant in OPA1 gene might be the causative variant in this ADOA family.Notably, this is the first report of this specific variant.

KEYWORDS：