Assessment of Immunoglobulin Heavy Variable Gene Usage and Somatic Hypermutation
Status in Splenic Marginal Zone Lymphomas Using Next Generation Sequencing
J. Gomez-Gelvez, C. Ho, W. Yu, M.H. Syed, A. Zehir, T. Baldi, A. Dogan, M. Ladanyi, J. Yao, K. Nafa, and M.E. Arcila
Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY

INTRODUCTION

H59

CASE 10: IGHV4-34/J6 USAGE

Splenic marginal zone lymphoma (SMZL) is a rare indolent B-cellneoplasm involving the spleen, bone marrow (BM) and, frequently,
blood. Its distinction from similar indolent B-cell malignancies may
often be challenging, particularly when diagnosis must be based on theBM findings alone without the support of spleen histology. Priorstudies have shown that SMZL exhibit specific immunoglobulin heavy
variable gene (IGHV) gene biases which are distinct from otherentities and thus ancillary testing could be potentially utilized to aid in
the diagnosis or further stratifying this disease. This assessment is,however, often not feasible in the clinical setting as current methodsare laborious and not performed in most laboratories. In this study, weexplore the utility of next generation sequencing (NGS) for the clinicalcharacterization of IGHV in a cohort of SMZL and compare it to othersubtypes of marginal zone lymphomas (MZL) reported in theliterature.

METHODS
BM samples from patients with an established diagnosis of SMZL andsubmitted for routine clonality assessment were selected for the study.
After establishing the presence of IGH clonality by capillaryelectrophoresis, the samples were analyzed using an NGS assay
targeting IGH-FR1 (Lymphotrack, Invivoscribe) and sequenced byIllumina MiSeq. Data was analyzed using the LymphoTrack IGH-FR1
and Somatic Hypermutation (SHM) software. Clinical and ancillarylaboratory data were collected from the electronic medical records.

SUMMARY OF CASESRESULTS

Case No.

Sex

Age

IGHV Gene
Usage

IGHJ Gene
Usage

Somatic Hypermutation
Status

1F

57

V5-51

J4

Unmutated

2M

65

V3-23

J4

Hypermutated

3F80

V3-11

J4

Hypermutated

4M

63

V4-34

J4Hypermutated

5M47

V3-23

J1

Hypermutated

6F70

V4-39

J2Hypermutated

7M71

V4-61

J4Unmutated

RESULTS

8M78

V3-73

J6Unmutated

9M65

V3-9J5Hypermutated

A total of 20 BM samples were available for analysis (1 sample failedanalysis due to low DNA input). Patients included 8 women and 12
men with a median age at diagnosis of 68 years (range: 47 to 87).
IGHV families most frequently rearranged were IGHV3 (11/20, 55%)
and IGHV4 (6/20, 30%). The IGHV genes most frequently rearranged
were IGHV4-34 (4/20, 20%) followed by IGHV3-23 (2/20, 10%),
IGHV3-30 (2/20, 10%), IGHV3-33 (2/20, 10%), IGHV3-73 (2/20,10%) and IGHV1-3 (2/20, 10%). Using a 98% identity cut-off value,
12/20 cases (60%) showed SHM. Review of the literature showed asimilar pattern of IGHV usage to other subtypes of MZL.

10M

54

V4-34

J6Hypermutated

11M

66

V4-34

J4Hypermutated

12F

70

V3-33

J4Hypermutated

13M

75

V4-34

J4Unmutated

14F

62

V1-3J4Unmutated

15F71

V1-3J6Hypermutated

16F73

V3-73

J6Hypermutated

17M52

V3-33

J4Hypermutated

18M

47

V3-30

J4Unmutated

19M

87

V3-30

J6Unmutated

20M

77

V3-43

J1Unmutated We confirm that SMZL have a biased IGHV gene usage, which is inkeeping with prior literature.
 This usage, however, has significant overlap with other subtypes ofMZL considered in the differential diagnosis and therefore does notprovide a means of discrimination for diagnostic purposes. Thisfinding however, suggests that the pathogenesis of SMZL may
involve epitopes or an antigenic trigger common to other indolentlymphomas.
 Whether particular molecular characteristics of the IG receptors
might be associated with clinical outcome, genetic or phenotypicfeatures is an area the deserves further study.

REFERENCES
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