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.
ABSTRACT
Achromatopsia is a kind of autosomal recessive cone disorder.It occurs with nystagmus,photophobia,inability of color discrimination and severely reduced visual acuity.Five pathogenic genes had been reported to be associated with achromatopsia:cyclic nucleotide-gated (CNG)A3,CNGB3,guanine nucleotide binding protein alpha transduction active pepitide 2(GNAT2),phosphodiesterase (PDE)6C and PDE6H.They are crucial for cone phototransduction.Mutations of these genes can induce achromatopsia.Gene therapy,which can recover partial visual function,has been successfully used for the treatment of achromatopsia in animal model.Clinical features,pathogenic genes functions and mutations,the animal models and gene therapy of achromatopsia were reviewed.
ABSTRACT
Cerebral achromatopsia, which refers to a loss of color vision, is a rare complication of posterior circulation stroke. We report two patients who presented with achromatopsia and dyschromatopsia (incomplete form of achromatopsia) respectively after acute posterior cerebral artery infarction. Lingual and fusiform gyri within the occipito-temporal area are known to be responsible for color perception.