Accessory heterozygous mutations in cone photoreceptor CNGA3 exacerbate CNG channel–associated retinopathy

Markus Burkard, Susanne Kohl, Timm Krätzig, Naoyuki Tanimoto, Christina Brennenstuhl, Anne E. Bausch, Katrin Junger, Peggy Reuter, Vithiyanjali Sothilingam, Susanne C. Beck, Gesine Huber, Xi Qin Ding, Anja K. Mayer, Britta Baumann, Nicole Weisschuh, Ditta Zobor, Gesa Astrid Hahn, Ulrich Kellner, Sascha Venturelli, Elvir BecirovicPeter Charbel Issa, Robert K. Koenekoop, Günther Rudolph, John Heckenlively, Paul Sieving, Richard G. Weleber, Christian Hamel, Xiangang Zong, Martin Biel, Robert Lukowski, Matthias W. Seeliger, Stylianos Michalakis, Bernd Wissinger, Peter Ruth

Research output: Contribution to journalArticle

Abstract

Mutations in CNGA3 and CNGB3, the genes encoding the subunits of the tetrameric cone photoreceptor cyclic nucleotide–gated ion channel, cause achromatopsia, a congenital retinal disorder characterized by loss of cone function. However, a small number of patients carrying the CNGB3/c.1208G>A;p.R403Q mutation present with a variable retinal phenotype ranging from complete and incomplete achromatopsia to moderate cone dysfunction or progressive cone dystrophy. By exploring a large patient cohort and published cases, we identified 16 unrelated individuals who were homozygous or (compound-) heterozygous for the CNGB3/c.1208G>A;p.R403Q mutation. In-depth genetic and clinical analysis revealed a co-occurrence of a mutant CNGA3 allele in a high proportion of these patients (10 of 16), likely contributing to the disease phenotype. To verify these findings, we generated a Cngb3R403Q/R403Q mouse model, which was crossbred with Cnga3-deficient (Cnga3–/–) mice to obtain triallelic Cnga3+/– Cngb3R403Q/R403Q mutants. As in human subjects, there was a striking genotype-phenotype correlation, since the presence of 1 Cnga3-null allele exacerbated the cone dystrophy phenotype in Cngb3R403Q/R403Q mice. These findings strongly suggest a digenic and triallelic inheritance pattern in a subset of patients with achromatopsia/severe cone dystrophy linked to the CNGB3/p.R403Q mutation, with important implications for diagnosis, prognosis, and genetic counseling.

Original languageEnglish (US)
Pages (from-to)5663-5675
Number of pages13
JournalJournal of Clinical Investigation
Volume128
Issue number12
DOIs
StatePublished - Dec 3 2018

ASJC Scopus subject areas

  • Medicine(all)

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    Burkard, M., Kohl, S., Krätzig, T., Tanimoto, N., Brennenstuhl, C., Bausch, A. E., Junger, K., Reuter, P., Sothilingam, V., Beck, S. C., Huber, G., Ding, X. Q., Mayer, A. K., Baumann, B., Weisschuh, N., Zobor, D., Hahn, G. A., Kellner, U., Venturelli, S., ... Ruth, P. (2018). Accessory heterozygous mutations in cone photoreceptor CNGA3 exacerbate CNG channel–associated retinopathy. Journal of Clinical Investigation, 128(12), 5663-5675. https://doi.org/10.1172/JCI96098