Treatment strategies for dominantly inherited disorders typically involve silencing or ablating the pathogenic allele. CRISPR-Cas nucleases have shown promise in allele-specific knockout approaches when the dominant allele creates unique protospacer adjacent motifs that can lead to allele-restricted targeting. Here, we present a spacer-mediated allele-specific knockout approach that utilizes both SpCas9 variants and truncated single-guide RNAs to achieve efficient discrimination of a single-nucleotide mutation in rhodopsin (Rho)-P23H mice, a model of dominant retinitis pigmentosa. We found that approximately 45% of the mutant P23H allele was edited at the DNA level and that the relative RNA expression of wild-type Rho was about 2.8 times more than that of mutant Rho in treated retinas. Furthermore, the progression of photoreceptor cell degeneration in outer nuclear layer was significantly delayed in treated regions of the Rho-P23H retinas at 5 weeks of age. Our proof-of-concept study therefore outlines a general strategy that could potentially be expanded to examine the therapeutic benefit of allele-specific gene editing approach to treat human P23H patients. Our study also extends allele-specific editing strategies beyond discrimination within the protospacer adjacent motif sites, with potentially broad applicability to other dominant diseases.
Treatment strategies for dominantly inherited disorders typically involve silencing or ablating the pathogenic allele. CRISPR/Cas nucleases have shown promise in allele-specific knockout approaches when the dominant allele creates unique protospacer adjacent motifs (PAMs) that can lead to allele restricted targeting. Here, we present a spacer-mediated allele-specific knockout approach that utilizes both SpCas9 variants and truncated single guide RNAs (trusgRNAs) to achieve efficient discrimination of a single-nucleotide mutation in rhodopsin (Rho)-P23H mice, a model of dominant retinitis pigmentosa (RP). We found that approximately 45% of the mutant P23H allele was edited at DNA level, and that the relative RNA expression of wild-type Rho was about 2.8 times more than that of mutant Rho in treated retinas. Furthermore, the progression of photoreceptor cell degeneration in outer nuclear layer was significantly delayed in treated regions of the Rho-P23H retinas at five weeks of age. Our proof-of-concept study therefore outlines a general strategy that could potentially be expanded to examine the therapeutic benefit of allele-specific gene editing approach to treat human P23H patient. Our study also extends allele-specific editing strategies beyond discrimination within the PAM sites, with potentially broad applicability to other dominant diseases.
Abstract. The present study aimed to investigate genetic and environmental factors involved in the pathogenesis of congenital heart disease (CHD). A total of 61 familial pedigrees with CHD were analyzed, and 134 patients out of 761 family members had a diagnosis of CHD confirmed. The present study revealed that the prevalence of CHD in first-degree relatives (55/249, 22.0%) was significantly higher than that in second-degree relatives (18/526, 3.4%). Additionally, the recurrence rate of CHD in families in which the patient's mother (12/61) or sister (15/61) had CHD were significantly higher than in cases with the father (6/61) or brother (4/61) having CHD. The subtypes of CHD with increased risk of recurrence were ventricle septal defect (VSD) and atrial septal defect (ASD), followed by patent ductus arteriosus and tetralogy of fallot (TOF). In the 21 sets of twins among the 61 familial pedigrees analyzed, the concordance of both twins affected by CHD in identical and dizygotic twins was 94.4% (17/18) and 33.3% (1/3), respectively. Identical subtypes of CHD were identified in 10 out of 21 sets of twins. Of note, the following pattern was identified in three sets of the twins: One twin had TOF, while the other one had VSD. A risk factor survey revealed that threatened abortion in early pregnancy was associated with familial CHD. In conclusion, genetic factors may have important roles in the development of CHD, and TOF and VSD may have similar molecular mechanisms. Threatened abortion in early pregnancy is a novel environmental factor that may be specific in Chinese females with CHD.
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