Two novel compound heterozygous SAG mutations in an Italian patient with Oguchi disease: A genetic and multimodal retinal imaging study

• Published in: European journal of ophthalmology p. 11206721211027422
• Main Authors: Pilotto, Elisabetta, Trevisson, Eva, Nacci, Elisabetta Beatrice, Longhin, Evelyn, Guidolin, Francesca, Midena, Edoardo
• Format: Journal Article
• Language: English
• Published: United States 01.11.2022
• Subjects: OCT; Oguchi disease; Mizuo Nakamura phenomenon; congenital stationary night blindness; SAG gene
• ISSN: 1724-6016
• DOI: 10.1177/11206721211027422

Oguchi disease is a rare autosomal recessive retinal dystrophy, characterized by congenital stationary blindness and caused by pathogenic variants in and genes. The present study aimed to report an Italian patient affected by Oguchi disease, evaluated by means of a multimodal retinal imaging study and harboring two novel heterozygous pathogenic variants in the gene. A 60-year-old female complaining congenital stationary night blindness was investigated through fundus photograph, optical coherence tomography (OCT), electroretinography (ERG), and genetic testing. Fundus examination showed a golden-grayish fundus aspect. The rod response of the scotopic ERG was undetectable and mixed rod-cone response was electronegative. Fundus photographs obtained in light and in prolonged dark-adapted conditions allowed to detect the Mizuo-Nakamura phenomenon. Light condition OCT over the abnormal retinal regions showed high-intensity areas in the outer photoreceptor segment layer, that reduced with prolonged dark adaption. Genetic testing identified two rare heterozygous sequence variants in the gene: NM_000541.5:c.807delA p.(Glu270Lysfs*9) and NM_000541.5:c.1047-1G>C confirming the diagnosis of Oguchi disease. We identified the first Italian compound heterozygous patient harboring two novel alterations in the gene (a frameshift deletion and a splicing variant). The involvement of the gene in Oguchi disease is a common finding in Japanese population, but rarely identified in Caucasians. Clinical suspicion should prompt the molecular analysis of genes associated with this condition.