CRISPR RNA Engineering Enables Single Nucleotide Polymorphism Discrimination in Nucleic Acid Detection

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-based diagnostic systems have emerged as powerful platforms for sensitive nucleic acid detection, yet their clinical reliability is frequently constrained by off-target activation and insufficient discrimination of closely related sequences. This review synthesizes current advances aimed at enhancing the specificity of CRISPR diagnostics, with particular emphasis on the pivotal role of CRISPR RNA (crRNA) engineering. We detail how structural determinants of crRNA, including spacer length optimization, intentional mismatch design, secondary-structure modulation, chemical modification, strand-displacement gating, and synergistic design frameworks, govern CRISPR-mediated target recognition and define the energetic and kinetic thresholds for accurate cleavage. Key engineering strategies encompassing computational prediction and modeling, high-throughput screening, and hybrid guide architectures are systematically examined for their capacity to elevate single-nucleotide discrimination, stabilize reaction performance, and enable robust multiplexed detection for pathogen profiling and mutation identification. Despite rapid progress, outstanding challenges persist, including interference from complex clinical matrices, lack of unified evaluation standards, and scalability barriers that hinder clinical translation. Addressing these limitations through integrated crRNA design, system-level optimization, and standardized benchmarking will be essential for realizing the promise of CRISPR diagnostics. Ultimately, these advances are poised to support ultrasensitive, highly specific, and portable point-of-care testing, thereby accelerating precision medicine and strengthening infectious disease surveillance and management.