Base editing corrects the common Salla disease SLC17A5 c.115C>T variant

Area of Science:

• Genetics
• Molecular Biology
• Biochemistry

Background:

• Free sialic acid storage disorders (FSASDs) are severe genetic conditions caused by mutations in the SLC17A5 gene, leading to lysosomal dysfunction and neurological impairment.
• Current therapeutic options for FSASDs are non-existent, necessitating the development of novel treatment strategies.

Purpose of the Study:

• To evaluate the efficacy of CRISPR-Cas9-mediated adenine base editing (ABE) and homology directed repair (HDR) for correcting the common FSASD founder variant SLC17A5 c.115C>T.
• To assess the therapeutic potential of ABE in reducing free sialic acid (FSA) levels and ameliorating disease pathology in cellular and animal models.

Main Methods:

• Human dermal fibroblasts and mouse embryonic fibroblasts with the SLC17A5 c.115C>T variant were treated with CRISPR-Cas9 ABE and HDR systems.
• Correction efficiency, indel formation, and FSA levels were analyzed in treated cells.
• ABE efficacy was further validated in a mouse model.

Main Results:

• ABE demonstrated significantly higher correction efficiency with no detectable indels compared to HDR, which showed minimal correction and frequent indels.
• ABE treatment led to a significant reduction in FSA levels in patient-derived fibroblasts.
• The therapeutic effects of ABE were successfully recapitulated in mouse embryonic fibroblasts.

Conclusions:

• CRISPR-Cas9-mediated ABE is a feasible and effective therapeutic strategy for the SLC17A5 c.115C>T variant underlying FSASDs.
• Base editing offers a promising approach for monogenic diseases involving impaired transmembrane protein function.
• This study highlights the potential of ABE as a therapeutic modality for FSASDs and similar genetic disorders.