Scientific Reports (Jul 2018)

Genotype determination of the OPN1LW/OPN1MW genes: novel disease-causing mechanisms in Japanese patients with blue cone monochromacy

  • Satoshi Katagiri,
  • Maki Iwasa,
  • Takaaki Hayashi,
  • Katsuhiro Hosono,
  • Takahiro Yamashita,
  • Kazuki Kuniyoshi,
  • Shinji Ueno,
  • Mineo Kondo,
  • Hisao Ueyama,
  • Hisakazu Ogita,
  • Yoshinori Shichida,
  • Hidehito Inagaki,
  • Hiroki Kurahashi,
  • Hiroyuki Kondo,
  • Masahito Ohji,
  • Yoshihiro Hotta,
  • Tadashi Nakano

DOI
https://doi.org/10.1038/s41598-018-29891-9
Journal volume & issue
Vol. 8, no. 1
pp. 1 – 10

Abstract

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Abstract Blue cone monochromacy (BCM) is characterized by loss of function of both OPN1LW (the first) and OPN1MW (the downstream) genes on the X chromosome. The purpose of this study was to investigate the first and downstream genes in the OPN1LW/OPN1MW array in four unrelated Japanese males with BCM. In Case 1, only one gene was present. Abnormalities were found in the promoter, which had a mixed unique profile of first and downstream gene promoters and a −71A > C substitution. As the promoter was active in the reporter assay, the cause of BCM remains unclear. In Case 2, the same novel mutation, M273K, was present in exon 5 of both genes in a two-gene array. The mutant pigments showed no absorbance at any of the wavelengths tested, suggesting that the mutation causes pigment dysfunction. Case 3 had a large deletion including the locus control region and entire first gene. Case 4 also had a large deletion involving exons 2–6 of the first gene. As an intact LCR was present upstream and one apparently normal downstream gene was present, BCM in Case 4 was not ascribed solely to the deletion. The deletions in Cases 3 and 4 were considered to have been caused by non-homologous recombination.