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        Genomic study revealing

        among diverse populations

        with inherited retinal disease

        International effort identified new and different causative gene variants
        for a group of diseases that can lead to severe vision loss or blindness

              n international team of        IRDs are rare, but they affect      of an individual. It provides a
              researchers, led by scientists   individuals of all ages, progressing   comprehensive portrait of the
        Aat University of California San     at different rates, even within     person’s entire genome, including
        Diego and Shiley Eye Institute at UC   families afflicted with the same   mutations and variants, which can
        San Diego Health, has broadened      disease. Specific diagnosis         be used for broad comparative
        and deepened understanding of        depends on finding the genetic      purposes.
        how inherited retinal dystrophies    causative mutations.
        (IRDs) affect different populations                                      Study participants were recruited
        of people and, in the process, have   The U.S. Food and Drug             from three different geographic
        identified new gene variants that    Administration has approved gene    regions: Mexico, Pakistan and
        may cause the diseases.              therapy for treating one form of IRD   European Americans living in the
                                             involving the gene RPE65, but for   United States. Genomic analyses
        The findings published in the        other IRDs caused by mutations      were conducted from blood
        October 18, 2021 issue of PLOS       in more than 280 different genes,   samples taken from all participants,
        Genetics.                            there are no cures or treatments    which revealed causative variants in
                                             proven to slow disease progression.  62 of the 108 lineages. A total of 94
        IRDs are a group of diseases,                                            gene variants were found in the 62
        from retinitis pigmentosa to         The researchers conducted whole-    families: 52 variants had previously
        choroideremia, that result in        genome sequences (WGS) of 409       been identified as causative and
        progressive vision loss, even        persons from 108 unrelated family   42 had not. Surprisingly, more than
        blindness. Each IRD is caused by     lineages, each with a previously    half of the new variants were not
        at least one gene mutation, though   diagnosed IRD. WGS is a process
        mutations in the same gene may       of determining the entirety, or
        lead to different IRD diagnoses.     near-entirety, of the DNA sequence                            7

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