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07.10.2016 | Clinical Investigation | Ausgabe 1/2017

Japanese Journal of Ophthalmology 1/2017

In vivo imaging of a cone mosaic in a patient with achromatopsia associated with a GNAT2 variant

Japanese Journal of Ophthalmology > Ausgabe 1/2017
Shinji Ueno, Ayami Nakanishi, Taro Kominami, Yasuki Ito, Takaaki Hayashi, Kazutoshi Yoshitake, Yuichi Kawamura, Kazushige Tsunoda, Takeshi Iwata, Hiroko Terasaki



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.

Patient and 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.


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.


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.

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