Gastroenterology. 2023 Jul 13. pii: S0016-5085(23)04769-8. [Epub ahead of print]
Anil K Giri,
Mervi Aavikko,
Linnea Wartiovaara,
Toni Lemmetyinen,
Juha Karjalainen,
Juha Mehtonen,
Kimmo Palin,
Niko Välimäki,
Max Tamlander,
Riikka Saikkonen,
Auli Karhu,
Ekaterina Morgunova,
Benjamin Sun,
Heiko Runz,
Priit Palta,
Shuang Luo,
Heikki Joensuu,
Tomi P Mäkelä,
Iiro Kostiainen,
Camilla Schalin-Jäntti,
FinnGen,
Aarno Palotie,
Lauri A Aaltonen,
Saara Ollila,
Mark J Daly.
BACKGROUND AND AIMS: Small intestinal neuroendocrine tumor (SI-NET) is a rare disease whose incidence has increased over the last 4 decades. Understanding the genetic risk factors underlying SI-NETs can help in disease prevention and may provide clinically beneficial markers for diagnosis. Here, we report the results of the largest genome-wide association study (GWAS) of SI-NETs performed to date with 405 cases and 614,666 controls.METHODS: We used samples from 307 SI-NET patients and 287,137 controls in the FinnGen study for the identification of SI-NET risk-associated genetic variants. We also metanalysed the results with summary statistics from the UK Biobank (n=98 SI-NET cases and n=327,529 controls).
RESULTS: We identified 6 genome-wide significant (p<5x10-8) loci associated with SI-NET risk, of which 4 (near SEMA6A, LGR5, CDKAL1, and FERMT2) are novel and 2 (near LTA4H-ELK and in KIF16B) have been previously reported. Interestingly, the top hit (rs200138614, p=1.80x10-19) is a missense variant (p.Cys712Phe) in the LGR5 gene, a bona fide marker of adult intestinal stem cells and a potentiator of canonical WNT signaling. The association was validated in an independent Finnish collection of 70 SI-NET patients, as well as in the UK Biobank exome sequence data (n=92 cases and n=392,814 controls). Overexpression of LGR5 p.Cys712Phe in intestinal organoids abolished the ability of R-Spondin1 to support organoid growth, indicating that the mutation perturbed R-Spondin-LGR5 signaling.
CONCLUSION: Our study is the largest GWAS study to date on SI-NETs and reports 4 new associated GWAS loci, including a novel missense mutation (rs200138614, p.Cys712Phe) in LGR5, a canonical marker of adult intestinal stem cells.
Keywords: CDKAL1; FERMT2; FinnGen; SEMA6A; SI-NET