Decoding the complexity of on-target integration: characterizing DNA insertions at the CRISPR-Cas9 targeted locus using nanopore sequencing.

BACKGROUND: CRISPR-Cas9 technology has advanced in vivo gene therapy for disorders like hemophilia A, notably through the successful targeted incorporation of the F8 gene into the Alb locus in hepatocytes, effectively curing this disorder in mice. However, thoroughly evaluating the safety and specificity of this therapy is essential. Our study introduces a novel methodology to analyze complex insertion sequences at the on-target edited locus, utilizing barcoded long-range PCR, CRISPR RNP-mediated deletion of unedited alleles, magnetic bead-based long amplicon enrichment, and nanopore sequencing. RESULTS: We identified the expected F8 insertions and various fragment combinations resulting from the in vivo linearization of the double-cut plasmid donor. Notably, our research is the first to document insertions exceeding ten kbp. We also found that a small proportion of these insertions were derived from sources other than donor plasmids, including Cas9-sgRNA plasmids, genomic DNA fragments, and LINE-1 elements. CONCLUSIONS: Our study presents a robust method for analyzing the complexity of on-target editing, particularly for in vivo long insertions, where donor template integration can be challenging. This work offers a new tool for quality control in gene editing outcomes and underscores the importance of detailed characterization of edited genomic sequences. Our findings have significant implications for enhancing the safety and effectiveness of CRISPR-Cas9 gene therapy in treating various disorders, including hemophilia A.

Adult-onset congenital intestinal malrotation: A case report and literature review.

BACKGROUND: Intestinal malrotation is an infrequent congenital anomaly primarily observed in neonates, and adult-onset cases are exceedingly rare. Studies on adult congenital intestinal malrotation are limited. METHODS: A case with congenital intestinal malrotation is reported in our study. The clinical data were collected and the treatment process and effect were evaluated. RESULTS: A 45-year-old female who had been experiencing vomiting for over 40 years was admitted to our hospital. According to the result of CT scan, intestinal volvulus accompanied by bowel obstruction was suspected. Then laparoscopic examination was applied to the patient and was ultimately diagnosed with adult congenital intestinal malrotation. We performed Ladd's procedure combined with gastrojejunostomy and Braun anastomosis. The patient recovered well and was successfully discharged from the hospital on the 13th day after surgery. After a 6-month follow-up, the symptom of vomiting was significantly alleviated and body weight was gained for 10 kg. She was very satisfied with the treatment. CONCLUSION: Adult congenital intestinal malrotation is a rare disease that is often misdiagnosed owing to nonspecific clinical manifestations. Therefore, awareness about this condition should be enhanced. Surgery remains the cornerstone of treatment for this disease. Combining gastrojejunostomy and Braun anastomosis with the traditional Ladd procedure can optimize surgical outcomes.