TY - JOUR
T1 - Identification and Functional Characterization of G6PC2 Coding Variants Influencing Glycemic Traits Define an Effector Transcript at the G6PC2-ABCB11 Locus
AU - Mahajan, Anubha
AU - Sim, Xueling
AU - Ng, Hui Jin
AU - Manning, Alisa
AU - Rivas, Manuel A
AU - Highland, Heather M
AU - Locke, Adam E
AU - Grarup, Niels
AU - Im, Hae Kyung
AU - Cingolani, Pablo
AU - Flannick, Jason
AU - Fontanillas, Pierre
AU - Fuchsberger, Christian
AU - Gaulton, Kyle J
AU - Teslovich, Tanya M
AU - Rayner, N William
AU - Robertson, Neil R
AU - Beer, Nicola L
AU - Rundle, Jana K
AU - Bork-Jensen, Jette
AU - Ladenvall, Claes
AU - Blancher, Christine
AU - Buck, David
AU - Buck, Gemma
AU - Burtt, Noël P
AU - Gabriel, Stacey
AU - Gjesing, Anette Marianne Prior
AU - Groves, Christopher J
AU - Hollensted, Mette
AU - Huyghe, Jeroen R
AU - Jackson, Anne U
AU - Jun, Goo
AU - Justesen, Johanne Marie
AU - Mangino, Massimo
AU - Murphy, Jacquelyn
AU - Neville, Matt
AU - Onofrio, Robert
AU - Small, Kerrin S
AU - Stringham, Heather M
AU - Syvänen, Ann-Christine
AU - Trakalo, Joseph
AU - Abecasis, Goncalo
AU - Bell, Graeme I
AU - Blangero, John
AU - Cox, Nancy J
AU - Duggirala, Ravindranath
AU - Linneberg, Allan
AU - Jørgensen, Torben
AU - Hansen, Torben
AU - Pedersen, Oluf
AU - T2D-GENES consortium and GoT2D consortium
PY - 2015/1/27
Y1 - 2015/1/27
N2 - Genome wide association studies (GWAS) for fasting glucose (FG) and insulin (FI) have identified common variant signals which explain 4.8% and 1.2% of trait variance, respectively. It is hypothesized that low-frequency and rare variants could contribute substantially to unexplained genetic variance. To test this, we analyzed exome-array data from up to 33,231 non-diabetic individuals of European ancestry. We found exome-wide significant (P<5×10-7) evidence for two loci not previously highlighted by common variant GWAS: GLP1R (p.Ala316Thr, minor allele frequency (MAF)=1.5%) influencing FG levels, and URB2 (p.Glu594Val, MAF = 0.1%) influencing FI levels. Coding variant associations can highlight potential effector genes at (non-coding) GWAS signals. At the G6PC2/ABCB11 locus, we identified multiple coding variants in G6PC2 (p.Val219Leu, p.His177Tyr, and p.Tyr207Ser) influencing FG levels, conditionally independent of each other and the non-coding GWAS signal. In vitro assays demonstrate that these associated coding alleles result in reduced protein abundance via proteasomal degradation, establishing G6PC2 as an effector gene at this locus. Reconciliation of single-variant associations and functional effects was only possible when haplotype phase was considered. In contrast to earlier reports suggesting that, paradoxically, glucose-raising alleles at this locus are protective against type 2 diabetes (T2D), the p.Val219Leu G6PC2 variant displayed a modest but directionally consistent association with T2D risk. Coding variant associations for glycemic traits in GWAS signals highlight PCSK1, RREB1, and ZHX3 as likely effector transcripts. These coding variant association signals do not have a major impact on the trait variance explained, but they do provide valuable biological insights.
AB - Genome wide association studies (GWAS) for fasting glucose (FG) and insulin (FI) have identified common variant signals which explain 4.8% and 1.2% of trait variance, respectively. It is hypothesized that low-frequency and rare variants could contribute substantially to unexplained genetic variance. To test this, we analyzed exome-array data from up to 33,231 non-diabetic individuals of European ancestry. We found exome-wide significant (P<5×10-7) evidence for two loci not previously highlighted by common variant GWAS: GLP1R (p.Ala316Thr, minor allele frequency (MAF)=1.5%) influencing FG levels, and URB2 (p.Glu594Val, MAF = 0.1%) influencing FI levels. Coding variant associations can highlight potential effector genes at (non-coding) GWAS signals. At the G6PC2/ABCB11 locus, we identified multiple coding variants in G6PC2 (p.Val219Leu, p.His177Tyr, and p.Tyr207Ser) influencing FG levels, conditionally independent of each other and the non-coding GWAS signal. In vitro assays demonstrate that these associated coding alleles result in reduced protein abundance via proteasomal degradation, establishing G6PC2 as an effector gene at this locus. Reconciliation of single-variant associations and functional effects was only possible when haplotype phase was considered. In contrast to earlier reports suggesting that, paradoxically, glucose-raising alleles at this locus are protective against type 2 diabetes (T2D), the p.Val219Leu G6PC2 variant displayed a modest but directionally consistent association with T2D risk. Coding variant associations for glycemic traits in GWAS signals highlight PCSK1, RREB1, and ZHX3 as likely effector transcripts. These coding variant association signals do not have a major impact on the trait variance explained, but they do provide valuable biological insights.
U2 - 10.1371/journal.pgen.1004876
DO - 10.1371/journal.pgen.1004876
M3 - Journal article
C2 - 25625282
SN - 1553-7390
VL - 11
SP - 1
EP - 25
JO - P L o S Genetics
JF - P L o S Genetics
IS - 1
M1 - e1004876
ER -