Variants in pancreatic carboxypeptidase genes CPA 2 and CPB 1 are not associated with 1 chronic pancreatitis 2 3

40 Genetic alterations in the carboxypeptidase A1 gene (CPA1) are associated with 41 early-onset chronic pancreatitis (CP). Besides CPA1, there are two other human pancreatic 42 carboxypeptidases: CPA2 and CPB1. Here we examined whether CPA2 and CPB1 alterations 43 are associated with CP in Japan and Germany. All exons and flanking introns of CPA2 and 44 CPB1 were sequenced in 477 Japanese patients with CP (234 alcoholic, 243 non-alcoholic) 45 and in 497 German patients with non-alcoholic CP by targeted next generation sequencing 46 and/or Sanger sequencing. Secretion and enzymatic activity of CPA2 and CPB1 variants were 47 determined after transfection into HEK 293T cells. We identified six non-synonymous CPA2 48 variants (p.V67I, p.G166R, p.D168E, p.D173H, p.R237W and p.G388S); eight 49 non-synonymous CPB1 alterations (p.S65G, p.N120S, p.D172E, p.R195H, p.D208N, 50 p.F232L, p.A317V and p.D364Y) and one splice-site variant (c.687+1G>T) in CPB1. 51 Functional analysis revealed essentially complete loss of function in CPA2 variants p.R237W 52 and p.G388S and CPB1 variants p.R110H and p.D364Y. None of the CPA2 or CPB1 variants, 53 including those resulting in a marked loss of function, were overrepresented in patients with 54 CP. In conclusion, CPA2 and CPB1 variants are not associated with CP. 55 56