| 1. |
- Jacobson, S G, et al.
(author)
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Digenic inheritance of a ROM1 gene mutation with a peripherin/RDS or rhodopsin mutation in families with retinitis pigmentosa
- 1999
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In: Digital Journal of Ophthalmology. - 1542-8958. ; 5:6
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Journal article (peer-reviewed)abstract
- Two families with retinitis pigmentosa showed inheritance of an Arg-16-His ROM1 gene mutation with either an Arg-13-Trp RDS mutation or an Arg-135-Trp RHO mutation. The phenotypes of double and single heterozygotes were determined to examine the hypothesis that digenic inheritance may increase disease expression. In the family with ROM1 and RDS mutations, single heterozygotes were normal but one double heterozygote showed severe RP. Two other double heterozygotes, however, were normal by clinical and retinal function tests. In the family with ROM1 and RHO mutations, single heterozygotes with the RHO mutation all manifested RP, while a single heterozygote for the ROM1 mutation was normal. Disease severity was comparable in double heterozygotes and single heterozygotes HAVING the RHO mutation. We conclude that the Arg-16-His ROM1 gene mutation is non-pathogenic in the single heterozygous state, and there is no consistent evidence of digenic augmentation of pathogenicity in double heterozygotes carrying the Arg-16-His ROM1 mutation with either the benign Arg-13-Trp RDS mutation or the disease-causing Arg-135-Trp RHO mutation.
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| 2. |
- Wissinger, Bernd, et al.
(author)
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The landscape of submicroscopic structural variants at the OPN1LW/OPN1MW gene cluster on Xq28 underlying blue cone monochromacy
- 2022
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 119:27
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Journal article (peer-reviewed)abstract
- Blue cone monochromacy (BCM) is an X-linked retinal disorder characterized by low vision, photoaversion, and poor color discrimination. BCM is due to the lack of long-wavelength-sensitive and middle-wavelength-sensitive cone photoreceptor function and caused by mutations in the OPN1LW/OPN1MW gene cluster on Xq28. Here, we investigated the prevalence and the landscape of submicroscopic structural variants (SVs) at single-base resolution in BCM patients. We found that about one-third (n = 73) of the 213 molecularly confirmed BCM families carry an SV, most commonly deletions restricted to the OPN1LW/OPN1MW gene cluster. The structure and precise breakpoints of the SVs were resolved in all but one of the 73 families. Twenty-two families—all from the United States—showed the same SV, and we confirmed a common ancestry of this mutation. In total, 42 distinct SVs were identified, including 40 previously unreported SVs, thereby quadrupling the number of precisely mapped SVs underlying BCM. Notably, there was no “region of overlap” among these SVs. However, 90% of SVs encompass the upstream locus control region, an essential enhancer element. Its minimal functional extent based on deletion mapping in patients was refined to 358 bp. Breakpoint analyses suggest diverse mechanisms underlying SV formation as well as in one case the gene conversion-based exchange of a 142-bp deletion between opsin genes. Using parsimonious assumptions, we reconstructed the composition and copy number of the OPN1LW/OPN1MW gene cluster prior to the mutation event and found evidence that large gene arrays may be predisposed to the occurrence of SVs at this locus.
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