Clinical and genetic features of a Chinese family with ATF6-associated achromatopsia / 中华实验眼科杂志

ABSTRACT

Objective:To identify the clinical characteristics and pathogenic gene of a Chinese Han family with achromatopsia (ACHM).Methods:The method of pedigree investigation was adopted.A Chinese Han ACHM family was recruited in Peking Union Medical College Hospital form July 2010 to July 2019, including 5 members of 2 generations.There were 2 patients and 3 phenotypically normal individuals.The medical history was collected and comprehensive ophthalmic examinations were performed, including visual acuity, colour vision, color fundus photography, fundus autofluorescence (FAF), optical coherence tomography (OCT), visual field and electroretinogram (ERG).Genomic DNA was extracted from peripheral blood sample from the patients and family members.Pathogenic variant was screened by whole exome sequencing (WES) and verified by Sanger sequencing and co-segregation analysis.The variant was annotated with the 1000 Genomes, Human Gene Mutation Database (HGMD), ExAC, ClinVar and OMIM databases to detect the single nucleotide polymorphism and whether it had been reported previously.The pathogenicity of the variant was evaluated according to the standards and guidelines of the American College of Medical Genetics and Genomics (ACMG).This study adhered to the Declaration of Helsinki.The study protocol was approved by the Institutional Review Board of Peking Union Medical College Hospital (No.JS-2059).Written informed consent was obtained from the guardians of juvenile patients.Results:There was consanguinity between the proband's parents and this family was consistent with autosomal recessive inheritance.Both male patients presented the reduction of visual acuity accompanied with photophobia and color blindness since childhood.Barely visible foveal light reflex in fundus images, hypofluorescence of foveal areas in FAF images, foveal defect with disruption of ellipsoid zone and interdigitation zone in OCT images were found in both patients.Central scotoma with or without peripheral visual field defects was detected.Generally normal scotopic 0.01, 3.0 and 10.0 responses, decreased oscillatory potentials amplitudes, no photopic 3.0 and 30 Hz flicker responses were observed.No sign of progression was found during the 9-year follow-up.It was confirmed that both patients carried a novel homozygous disease-causing variant c. 947insA (p.Asn316Lysfs*46) in ATF6 gene.Their mother had the heterozygous variant.The unaffected brother did not carry the variant.This family was consistent with co-segregation.This variant was labeled as pathogenic according to the ACMG standards and guidelines. Conclusions:A novel variant c.947insA (p.Asn316Lysfs*46) in ATF6 gene is the pathogenic variant of this achromatopsia family.This is the first time that this variant has been reported.