MIRLET7A1: MIRLET7A1 is a microRNA gene located on chromosome 9q22.3 [PMC5356719]. It is one of the three genes expressing let-7a, along with MIRLET7A2 on 11q24.1 and MIRLET7A3 on 22q13.3 [PMC5356719]. MIRLET7A1 has been studied in the context of adenoviral shuttle vectors and priMIR expression vectors [PMC6923634]. It is targeted by several miRNAs, including members of the let-7 family, suggesting potential auto-regulation [PMC7961530]. MIRLET7A1 has also been included in targeted capture assays for detecting structural variations and copy number analysis [PMC7815088]. In the context of acute lymphoblastic leukemia (ALL), variants in MIRLET7A1 have been associated with severe hematologic toxicity arising from treatment [PMC10003057]. Specifically, variants rs12904 (MIR200C), rs3746444 (MIR499A), and rs10739971 (MIRLET7A1) have shown significant associations with hematologic toxicity in ALL patients [PMC10003057]. Furthermore, the rs10739971 variant of MIRLET7A1 has been associated with a potential protective factor against toxic hematological events in pediatric patients undergoing ALL treatment [PMC10003057]. However, no significant differences have been found for genotype and allele frequencies of several miRNAs including MIRLET7A1 between cases and controls in a specific population studied for breast cancer susceptibility [PMC4650490]. Chromosomal loss at 9q22 has also led to recurrent loss of the MIRLET7A gene family, including MIRLET7A1 [PMC7459851]. Overall, studies suggest that MIRLET7A1 plays regulatory roles in cellular processes and may have implications in cancer and therapeutic response [PMC8840188] [PMC10003057] [PMC7459851].