Genetic variation near GRB2 and KCNB2 identified by a genome-wide association

study is reproducibly associated with Diabetic Retinopathy

Kathryn P Burdon, Rhys Fogarty, Nikolai Petrovsky, Mark Gillies, Mark Daniell, Sotoodeh Abhary, Gowthaman Govindarjan, Periasamy Sundaresan, Georgia

Kaidonis, Alicia Jenkins, John Chang, Rohan Essex, Bishwanath Pal, Jamie E Craig

The Eye and Retina

Diabetic Retinopathy Non-Proliferative Retinopathy Proliferative Retinopathy

Normal Macula Macular Edema

Prevalence of Diabetic Retinopathy

* Kempen, J.H., B.J. O'Colmain, M.C. Leske, et al., The prevalence of diabetic retinopathy among adults in the United States. Arch Ophthalmol, 2004. 122:552-63

Study Any DR Sight Threatening DR

BMES 29% 6.4%

MVIP 27.5% 4.3%

AusDiab 22% -

ANNDIAB 30% 7%

Meta-analysis* 40% 8%

Risk Factors Diabetes

duration

Diabetic Retinopathy

High blood

pressure

High cholesterol Smoking Nephropathy

Poor Blood

Sugar Control

Genetics

Genome Wide Association Study for Diabetic Retinopathy

Controls: No DR Cases: DR

Caucasians with medically treated type 2 diabetes for at least 5 years

Cohorts

Discovery and Replication samples

Replication samples

Australia India

United Kingdom

Discovery Cohort

Phenotype N

Controls No DR 654

Any DR

Non-proliferative DR 408

Proliferative DR 224

Macular Edema 330

Sight Threatening 427

Total Participants 1150

Discovery Cohort Characteristics

Cases Controls P-value

Age (yrs) 66.2 ± 10.7 67.0 ± 12.4 0.255

Duration of diabetes (yrs) 18.3 ± 9.1 12.6 ± 7.6 <0.001

% Female 41.1% 47.4% 0.061

BMI (kg/m2) 32.4 ± 7.0 32.2 ± 6.9 0.525

HbA1c (%) 8.4 ±1.7 7.5 ± 1.4 <0.001

Hypertension 86.5 % 77.2% <0.001

Nephropathy 24.2% 11.6% <0.001

Typing and Analysis

• Illumina OmniExpress SNP array

– 617130 SNPs QC

• Data Cleaning

– Removed SNPs with low MAF, poor genotyping or not in HWE

– Remove related individuals (pi-hat>0.3)

– Principal components (Eigenstrat) with removal of ethnic outliers (>6SD from mean)

• Association analysis (PLINK)

– Lambda = 1.02

Any DR

Chr: 1 2 3 4 5 6 7 8 9 10 11 12 14 16 18 20 22

-lo

g 10P

-val

ue

2.0x10-8

Sight Threatening DR

4.7x10-8

Chr: 1 2 3 4 5 6 7 8 9 10 11 12 14 16 18 20 22

-lo

g 10P

-val

ue

Adjusted for duration of diabetes, HbA1c, nephropathy, hypertension and sex

Replication

rs7839922 Any DR

Chr 17 - rs9896052 Blinding DR

Cohort N

Case/Con Odds Ratio P-value

N Case/Con

Odds Ratio

P-value

GWAS 616/474 1.7 2.01x10-8 335/511 1.94 4.71x10-8

T2 525/300 1.33 0.010 122/226 1.50 0.035

T1 242/126 1.01 0.940 242/126 1.47 0.022

Indian 334/327 0.99 0.905 334/327 1.37 0.005

Cohort

Discovery

T2DM Caucasian

T1DM Caucasian

T2DM Indian

Chr 8 - rs7839922 Any DR

N Case/Con

Odds Ratio

P-value

616/474 1.70 2.01x10-8

525/300 1.33 0.010

242/126 1.01 0.940

334/327 0.99 0.905

GRB2 Function

• Insulin receptor • VEGF receptor • EGF receptor • EPO receptor

Adaptor molecule for receptor tyrosine kinases

GRB2 Function

• Insulin receptor • VEGF receptor • EGF receptor • EPO receptor

Adaptor molecule for receptor tyrosine kinases

Conclusion

• Chr8 (KCNB2) region associated with DR in Caucasian type 2 diabetes

• Chr17 (GRB2) region associated with sight threatening DR in type 1 and type 2 diabetes and multiple ethnicities, independently of other clinical risk factors

• First report of replicated, genome-wide significant loci for DR

Acknowledgements • Flinders University/Flinders

Medical Centre

– Jamie Craig, Rhys Fogarty, Sue Abhary, Emmanuelle Souzeau, Stacey Thorpe, John Chang, Georgia Kaidonis, Kathleen Dowell

• Sydney Eye Hospital

– Mark Gillies, Mila Kolmogorova

• Royal Melbourne Hospital

– Mark Daniell, Fiona Richter

• Canberra Hospital

– Rohan Essex, Jennifer Saarikko

• St Vincents Hospital Melbourne

– Alicia Jenkins

• Centre for Eye Research Australia

– Alex Hewitt

• Moorefields Eye Hospital

– Bishwanath Pal

• Aravind Medical Research Institute, India

– Periasamy Sundaresan, Gowthaman Govindarjan

• Diamantina Institute

– Matthew Brown, Patrick Danoy, Paul Leo