1. Next Generation Sequencing based comprehensive
molecular studies in young onset diabetes
Aaron Chapla, Deny Varghese, Manika Varshney, Ridhi Dasgupta, Mercy Inbakumari,
Asha HS,Deepak Abraham*, Thomas V Paul, Nihal Thomas.
Departments Of Endocrinology1, Endocrine Surgery*, Christian Medical College, Vellore, India.
BACKGROUND: T2DM pathophysiology which is characterized by insulin resistance and relative impairment in insulin secretion can be explained in individuals whose BMI is above 25 Kg/m2. In T2D, β cells via the feedback loop compensate to the increasing need of insulin and maintain a fine balance with the insulin sensitive tissues to sustain normoglycemia and the onset of T2D is usually above 35 years.
HYPOTHESIS

2. STRATIFICATION OF STUDY SUBJECTS NEXT GENERATION SEQUENCING
METHODS
STRATIFICATION OF STUDY SUBJECTS
NEXT GENERATION SEQUENCING
BASED METHODOLOGY

3. MUTATIONS IDENTIFIED UTILIZING THE 2GDMODY PROTOCOL
MEPN
Sex
Age
AOD
BMI
TREATMENT
GENE
MODY
Mutation
Aminoacid change
M85 F 37 27
21.7
Insulin
HNF4A*
MODY1
c.811G>A
p.Glu271Lys
M10 M 23 21 25
Metformin
HNF4A
c.505G>A c.493-4G>A (splice site mutation) c C>T
p.Val169Ile
BLK
c.953G>A
p.G318E
M15 8
Diet
GCK
MODY2
c.1318G>T
p.Glu440X
M01 11
19.1
Insulin & Glibenclamide
HNF1A
c.1501G>T
p.Ala501Ser
ABCC8
c.1555G>A
p.R519C
M62 40 26
24.4
PDX1
MODY4
c.529G>A
p.Val177Met
M19
26.3
Metformin & Insulin
HNF1B
MODY5
c.274C>T
p.Leu92Phe
M26 47 28
22.8
Glimepiride
NEUROD1
c.723C>G
p.His241Gln
c.670G>A
p.Glu224Lys
M47 35 24
39.7
Metformin & Glimepride
MODY6
M18 30
19.3
c.175 G>C
p.Glu59Gln
M30
27.5
Metformin & Glipizide
c.-162G>A 5'UTR
M33 14
Glimepiride & Insulin
PAX4
c.92G>T
p.Arg31Leu
c.487C>T
p.G163S
M05 52 32
Metformin & Glimepride 
MODY12 
M12 29
Insulin  
MODY12
c.1005C>A
p.Q335H
M32
Metformin 
c.3995G>A
p.S1332L
M43
 Metformin
MODY ?  
c.2209C>T
p.V737I
M29
KCNJ11
MODY13 
c.247A>G
p.W83R

4. Summary of mutations in MODY subjects
Group I- N =56
Clinically suspected MODY
Group II- N =24
Young onset diabetes
N=15
N=41
N=1
N=23
N=6
BMI-22.7±2.9
N=12
N=4
BMI-27.6±5
N=6
N=9

5. Summary and conclusions of the study
Through this study NGS based cost-effective, scalable, accurate molecular method was established for comprehensive parallelized genetic testing in clinical settings
We have identified 27% mutation positive rate in subjects with suspected MODY and 4% mutation positive rate in subjects with young onset diabetes when screened for a complete panel of all the known 13 MODY genes.
First report of PDX1, HNF1Β, PAX4, KLF11, BLK11 novel mutations from India and also first report of novel digenic NEUROD1+PDX1, PAX4+ABCC8, HNF4A+ABCC8 mutations.
The subjects with digenic mutations (6/15) had a mean BMI of 22.7kg/m2 and those subjects with single gene mutation had a BMI of 28kg/m2 . This data suggest that subjects with higher mutational burden could be predisposed to develop diabetes even with low BMI.
Reference: Aaron Chapla, Mahesh Doddabelavangala Mruthyunjaya, Hesarghatta Shyamasunder Asha, Denny Varghese, Manika Varshney, Senthil K Vasan,
Padmanaban Venkatesan, Veena Nair, Sarah Mathai, Thomas Vizhalil Paul and Nihal Thomas. Maturity onset diabetes of the young in india.-a distinctive mutation
pattern identified through targeted next generation sequencing. Clinical Endocrinology, Volume 82, Issue 4, April 2015 Pages 533–542.