Next-Generation Sequencing and Variant Cataloguing for Screening and Diagnosis of Mucolipidoses and Other Lysosome-Related Organelle Disorders, Including Lysosomal Membrane or Transport Disorders.

Next-generation sequencing (NGS) has transformed the diagnostic landscape for inherited metabolic diseases by enabling high-resolution detection of pathogenic variants across genetically heterogeneous lysosomal pathways. This is particularly impactful for lysosomal diseases (LDs), including the mucolipidoses (ML I-IV), and for disorders involving lysosomal membranes, transporters, and lysosome-related organelles (LROs). These conditions often present with overlapping biochemical and clinical features that historically complicated accurate diagnosis. This review synthesizes current knowledge on the application of next-generation sequencing (NGS) technologies in the detection and interpretation of variants underlying mucolipidoses types I-IV and selected LRO and lysosomal membrane transport disorders. We summarize expanded variant catalogues, genotype-phenotype correlations, and functional evidence informing pathogenicity classification. In addition, we discuss the integration of NGS into newborn screening and population-level genomics. Collectively, these advances have refined disease definitions, resolved diagnostically challenging cases, and reshaped clinical workflows across the LD and LRO disease spectra.