J.M. Reynolds1, D.B. Lloyd2, K.G. Spink3, J.F. Zobel4, G.I. Johnston5

1DNA and BioFluids RCoE , Pfizer Inc., Groton, CT, USA.; 2CVMED Research Unit, Pfizer Inc., Groton, CT, USA.; 3Research Enabling Group, Pfizer Inc., Sandwich, Kent, UK.; 4Bioprocess Analytic, Pfizer Inc., Chesterfield, MO, USA.;

5Molecular Medicine, Pfizer Inc., Sandwich, Kent, UK.

BACKGROUND The sequence encoding the constant heavy chain

of IgE (IGHE) has two highly homologous

pseudogenes, IGHEP1 located on chr.14 and

IGHEP2 located on chr.9.

Many of the polymorphisms reported in dbSNP for

IGHE constant domains 3 and 4 are located at

positions of disagreement between IGHE and

IGHEP1, suggesting that these polymorphisms

may be false due to co-amplification of IGHE and

IGHEP1.

To determine the true variation of IGHE, the

constant domains 3 and 4, along with the IVS

were amplified and sequenced using primers

unique to IGHE from a diverse ethnic DNA panel.

SUBJECTS AND METHODS 102 gDNAs obtained from the Coriell Cell Repository (24 African American, 34 Asian, 24 Caucasian, and 20 Hispanic) were resequenced for the IGHE constant

domains and IVS. IgE wild-type protein and IgE protein containing the W480G polymorphism were measured for XOLAIR® (Genentech, Novartis) binding using

Biacore® technology.

CONCLUSIONS

Several of the polymorphisms reported in dbSNP (rs1134585, rs1134587, rs1134589, and rs17841077) were not observed in the panel of 102 individuals. Six novel

polymorphisms were observed.

One of the polymorphisms, W480G, was estimated to be common in the Asian population with a minor allele frequency of 35.3%. Since this polymorphism may affect

binding of anti-IgE therapeutic antibodies, we examined the binding of a marketed therapy, XOLAIR®, to IgE containing the W480G polymorphism compared to wild-

type IgE. No difference in binding was observed with XOLAIR®, however it may be important to test binding of novel IgE targeted therapies to IgE containing W480G

pre-clinically to avoid any potential pharmacogenetic effects once in the clinic.

Frequency and function of a common

IgE heavy chain (IGHE) variant

Figure 1. Sequence comparison of IGHE and IGHEP1 for a portion of CH4

Table 1. Polymorphism Frequency Table Figure 2. Comparison of XOLAIR® binding to wild-type IgE and IgE

containing the W480G polymorphism

Ethnicity

Polymorphism African

American

n=24

Asian

n=34

Caucasian

n=24

Hispanic

n=20

A391V

TGGACCTGG(C/T)ACCCAGCA

0.0% 1.5% 0.0% 0.0%

Intron3+9

GTGAGCCA(T/C)GGGCAGGCC

10.4% 32.4% 0.0% 2.5%

A474A

TCTATGC(G/A)TTTGCGACG

4.2% 0.0% 4.2% 0.0%

A476V

TATGCGTTTG(C/T)GACGCCGGAG

10.4% 0.0% 0.0% 2.5%

W480G

CGACGCCGGAG(T/G)GGCCG

10.4% 35.3% 0.0% 2.5%

P481L

rs1134585 0.0% 0.0% 0.0% 0.0%

A490T

rs1134587

0.0% 0.0% 0.0% 0.0%

V532I

rs1134589

0.0% 0.0% 0.0% 0.0%

E542E

rs17841077 0.0% 0.0% 0.0% 0.0%

A558A,

rs4983454

CCATGAGGCAGC(G/A)AGCCCCTCA

16.7% 0.0% 0.0% 2.5%

P572A

GTCTGTAAAT(C/G)CCGGTAAATGA

2.1% 0.0% 0.0% 0.0%

XOLAIR® binding to IgE wild-type

XOLAIR® binding to IgE with the W480G polymorphism

XOLAIR® binding to

IgE wild-type

Ka = 2.8x106 (1/M·s)

Kd = 2.9x10-4 (1/s)

KD = 104 pM

XOLAIR® binding to IgE containing W480G

Ka = 2.5x106 (1/M·s)

Kd = 2.7x10-4 (1/s)

KD = 105 pM

Presented at ASHG 2010