title: In vivo imaging of a cone mosaic in a patient with achromatopsia associated with a GNAT2 variant.
abstract: OBJECTIVE
  The 2 most common causative genes for achromatopsia (ACHM) are CNGA3 and CNGB3; other genes including GNAT2 account for only a small portion of ACHM cases. The cone mosaics in eyes with CNGA3 and CNGB3 variants are severely disrupted; the cone mosaics in patients with GNAT2-associated ACHM; however, have been reported to show a contiguous pattern in adaptive optics (AO) retinal images. The purpose of this study was to analyze the cone mosaic of another case of GNAT2-associated ACHM.
  
  
  METHODS
  The patient was a 17-year-old Japanese boy. Comprehensive ocular examinations including fundus photography, electroretinography (ERGs), optical coherence tomography (OCT), and whole-exome analysis were performed. The cone mosaic was recorded with a flood-illuminated AO fundus camera, and the cone density was compared with those of 10 normal control eyes.
  
  
  RESULTS
  The patient had the typical phenotype of ACHM, and a novel homozygous variant, c.730_743del, in GNAT2 was identified. The fundus did not show any specific abnormalities, and the OCT images showed the presence of the ellipsoid zone. The AO fundus image showed a clearly defined cone mosaic around the fovea. The cone density at 500 μm from the fovea was reduced by 15-30 % as compared with those of the normal eyes.
  
  
  CONCLUSIONS
  This is the first description of a Japanese patient with ACHM with a novel GNAT2 variant. The eyes of this patient had a preserved cone structure with loss of function.
authors.affiliation: Department of Ophthalmology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, 466-8550, Japan. ueno@med.nagoya-u.ac.jp.
authors.forename: Shinji
authors.initials: S
authors.lastname: Ueno
authors.affiliation: Department of Ophthalmology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, 466-8550, Japan.
authors.forename: Ayami
authors.initials: A
authors.lastname: Nakanishi
authors.affiliation: Department of Ophthalmology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, 466-8550, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Kominami
authors.affiliation: Department of Ophthalmology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, 466-8550, Japan.
authors.forename: Yasuki
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Hayashi
authors.affiliation: National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Yoshitake
authors.affiliation: National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kawamura
authors.affiliation: National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Tsunoda
authors.affiliation: National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Iwata
authors.affiliation: Department of Ophthalmology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, 466-8550, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Terasaki
mesh_terms: D000293:Adolescent; D003117:Color Vision Defects / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D004596:Electroretinography; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D014644:Genetic Variation; D006801:Humans; D008297:Male; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology*; D014792:Visual Acuity; D058609:Visual Field Tests
chemical_list: D005136:Eye Proteins
keywords: Achromatopsia; Adaptive optics (AO); GNAT2 gene; Spectral domain optical coherence tomography (SD-OCT)