PURPOSE: Pituitary tumours are relatively common, and familial in approximately 5% of cases. However, germline genetic contributions to pituitary tumour development are incompletely characterised. Preliminary evidence suggests pituitary tumours may be promoted by variants in pituitary organogenesis genes. Our study aimed to identify rare germline variants in pituitary organogenesis genes that may contribute to pituitary tumour development. METHODS: A familial case of pituitary disease was investigated. We also examined 36 pituitary organogenesis genes in 134 individuals with pituitary tumours using a targeted next-generation sequencing panel, identifying and characterising variants with a population allele frequency <
0.05%. RESULTS: One patient with a prolactin-secreting pituitary tumour and his daughter with combined pituitary hormone deficiency shared a rare germline variant in FGFR1, c.386 A >
C, p.(D129A). In our broader study, we identified an additional individual with the FGFR1 D129A variant and demonstrated enrichment compared to a control population derived from the Genome Aggregation Database (gnomAD). We also observed 66 rare germline variants in pituitary organogenesis genes amongst 54/134 individuals (40%). However, compared to control data, the study cohort exhibited no enrichment for other rare variants in FGFR1, FGF-related genes, or other pituitary embryogenesis genes. CONCLUSION: Our results suggest that the FGFR1 D129A variant may be associated with pituitary tumorigenesis but the role of other pituitary embryogenesis genes remains unclear. Additional independent cohorts and functional studies are required.