Aims Myeloid neoplasms (MNs) with germline predisposition have been recognised as a distinct entity. Emerging evidence suggests that sporadic myelodysplastic syndromes may also harbour undetected germline predispositions. We investigated germline alterations in a cohort of 122 adult Thai MNs.

Methods MN patients were recruited and tested for germline variants using deep targeted next-generation sequencing. The germline variant was filtered using American College of Medical Genetics classifications and then evaluated for the association with clinical characteristics and outcomes.

Results Our findings revealed pathogenic/likely pathogenic germline alterations in 12 (10%) of the patients. These germline lesions were commonly found in the DNA damage response pathway (n=6, 50%). We also identified novel deleterious FANCA^{A1219GfsTer59} variants in two patients diagnosed with secondary acute myeloid leukaemia (sAML) from aplastic anaemia and AML with myelodysplasia related. Among sAML, individuals with germline mutations had inferior overall survival compared with those with wild-type alleles (2 months vs 12 months) with HR 4.7 (95% CI 1.0 to 20), p=0.037. Therefore, the presence of pathogenic or likely pathogenic mutations may be linked to inferior survival outcomes.

Conclusions Our study highlighted that the prevalence of germline predisposition in Southeast Asian populations is comparable to that in Caucasians. This underscores the importance of germline genetic testing within the Asian population.