biostudies-literatureGhahremani SNHLBI NIH HHSNIGMS NIH HHS1285-1297https://www.ebi.ac.uk/biostudies/studies/S-EPMC11031707biostudies-literatureUnknown149(16)<h4>Background</h4><i>TTN</i> truncation variants (TTNtvs) are the most common genetic lesion identified in individuals with dilated cardiomyopathy, a disease with high morbidity and mortality rates. TTNtvs reduce normal TTN (titin) protein levels, produce truncated proteins, and impair sarcomere content and function. Therapeutics targeting TTNtvs have been elusive because of the immense size of TTN, the rarity of specific TTNtvs, and incomplete knowledge of TTNtv pathogenicity.<h4>Methods</h4>We adapted CRISPR activation using dCas9-VPR to functionally interrogate TTNtv pathogenicity and develop a therapeutic in human cardiomyocytes and 3-dimensional cardiac microtissues engineered from induced pluripotent stem cell models harboring a dilated cardiomyopathy-associated TTNtv. We performed CirculationCRISPR Activation Reverses Haploinsufficiency and Functional Deficits Caused by &lt;i&gt;TTN&lt;/i&gt; Truncation Variants.PMC11031707R01 HL165220R01 HL141086R35 GM119465U01 HL156349R01 HL142787Greenberg LZhu YTjong HStump WTGhahremani SGreenberg MJLegere NKanwal APettinato AHinson JTCotney JThakar KWei CLWilderman ALadha FfalseCRISPR Activation Reverses Haploinsufficiency and Functional Deficits Caused by &lt;i&gt;TTN&lt;/i&gt; Truncation Variants.<h4>Background</h4><i>TTN</i> truncation variants (TTNtvs) are the most common genetic lesion identified in individuals with dilated cardiomyopathy, a disease with high morbidity and mortality rates. TTNtvs reduce normal TTN (titin) protein levels, produce truncated proteins, and impair sarcomere content and function. Therapeutics targeting TTNtvs have been elusive because of the immense size of TTN, the rarity of specific TTNtvs, and incomplete knowledge of TTNtv pathogenicity.<h4>Methods</h4>We adapted CRISPR activation using dCas9-VPR to functionally interrogate TTNtv pathogenicity and develop a therapeutic in human cardiomyocytes and 3-dimensional cardiac microtissues engineered from induced pluripotent stem cell models harboring a dilated cardiomyopathy-associated TTNtv. We performed 2024-01-01T00:00:00Z2024 Apr2026-06-01T17:55:45.972Z2026-04-08T14:27:29.204ZS-EPMC110317073823559110.1161/circulationaha.123.06397210.1161/CIRCULATIONAHA.123.063972