BACKGROUND: Milk kinship, in some cultures, posits that infants who receive breast milk from non-biological mothers establish a consanguinity, prohibiting future marriage between the recipient infants and the biological children of the breastfeeding mother. This kinship may be influenced by specific miRNAs in breast milk that modulate gene expression epigenetically, leaving marks within the recipient infants. RESEARCH AIM: This study aims to identify lactation-specific miRNAs shared among milk siblings, compare miRNA similarity between a breastfeeding mother's milk and milk siblings' plasma, and determine their persistence post-infancy. METHODS: RNA was extracted from plasma and breast milk samples, followed by NanoString miRNA analysis to profile individual miRNAs. Differential Gene Expression (DGE) analysis using the R studio NOISeq package identified significantly expressed miRNAs across all samples. RESULTS: Detailed comparisons revealed that several similarly detected miRNAs in milk siblings were present in their corresponding breastfeeding mother's milk. DGE analysis identified five miRNAs: hsa-let-7b-5p, hsa-miR-223-3p, hsa-miR-873-3p, hsa-miR-23a-3p, and hsa-miR-378e, with hsa-miR-23a-3p exhibiting the most consistent expression pattern throughout the study. CONCLUSION: This study successfully identifies potential lactation-specific miRNAs that may be shared between milk siblings, providing valuable insights and laying a foundation for future identification of milk kinship biomarkers. However, despite promising findings, current evidence remains insufficient to establish a definitive link between these miRNAs and milk kinship. Further research is required to confirm these findings.
Ruddin et al. (Wed,) studied this question.