Sialidosis is a rare autosomal recessive lysosomal storage disorder caused by mutations in the NEU1 gene, resulting in deficient neuraminidase-1 activity and the subsequent accumulation of sialylated compounds in lysosomes. This review comprehensively analyzes the genetic and clinical heterogeneity associated with sialidosis, emphasizing the distinction between the milder type I form and the more severe type II form. Over 90 pathogenic NEU1 variants, predominantly missense mutations, have been identified, highlighting significant phenotypic diversity. Advancements in genomic sequencing technologies have facilitated the identification of known and novel mutations, with population-specific insights elucidating ethnic variability in symptomatology and genetic profiles. Recent case studies, including a novel compound heterozygous variant, further illustrate the complexity of the genotype–phenotype correlations. Emerging therapeutic approaches, such as enzyme replacement therapy and adeno-associated virus-mediated gene therapy, demonstrate promising potential for restoring neuraminidase-1 function and improving outcomes in preclinical models. This review emphasizes the critical role of genetic analysis in diagnosis and management while advocating for continued research into the molecular mechanisms underlying sialidosis to enable the development of targeted, personalized treatments.

Adipose-derived mesenchymal stem cells (ADSCs) have exhibited promising therapeutic potential in Alzheimer’s disease (AD), although the underlying mechanisms remain poorly understood. Previously established Alzheimer’s disease neuron models derived from Ts21-induced pluripotent stem cells (Ts21-iPSCs) have been shown to exhibit progressive amyloid beta accumulation during neuronal differentiation. In this study, we employed a Transwell co-culture system to investigate the interaction between neurons derived from Ts21-iPSCs and ADSCs. Our findings revealed that co-culture with ADSCs significantly enhanced the survival rate of AD neurons. Proteomics analysis identified significant upregulation of left–right determination factor 2 (LEFTY2) protein in the co-culture medium. Supplementation with 2 nM LEFTY2 markedly improved the survival and growth of AD neurons. Furthermore, LEFTY2 effectively downregulates the expression of apolipoprotein E4 and amyloid beta 1–42, along with attenuating phosphorylated tau231 levels in AD neurons. These results suggest the potential of LEFTY2 as a promising therapeutic candidate for Alzheimer’s disease.

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