Immunoglobulin heavy variable (IGHV) genes and alleles: new entities, new names and implications for research and prognostication in chronic lymphocytic leukaemia.
Νext generation sequencing studies in Homo sapiens have identified novel immunoglobulin heavy variable (IGHV) genes and alleles necessitating changes in the international ImMunoGeneTics information system (IMGT) GENE-DB and reference directories of IMGT/V-QUEST. In chronic lymphocytic leukaemia (CLL), the somatic hypermutation (SHM) status of the clonotypic rearranged IGHV gene is strongly associated with patient outcome. Correct determination of this parameter strictly depends on the comparison of the nucleotide sequence of the clonotypic rearranged IGHV gene with that of the closest germline counterpart. Consequently, changes in the reference directories could, in principle, affect the correct interpretation of the IGHV mutational status in CLL. To this end, we analyzed 8066 productive IG heavy chain (IGH) rearrangement sequences from our consortium both before and after the latest update of the IMGT/V-QUEST reference directory. Differences were identified in 405 cases (5 % of the cohort). In 291/405 sequences (71.9 %), changes concerned only the IGHV gene or allele name, whereas a change in the percent germline identity (%GI) was noted in 114/405 (28.1 %) sequences; in 50/114 (43.8 %) sequences, changes in the %GI led to a change in the mutational set. In conclusion, recent changes in the IMGT reference directories affected the interpretation of SHM in a sizeable number of IGH rearrangement sequences from CLL patients. This indicates that both physicians and researchers should consider a re-evaluation of IG sequence data, especially for those IGH rearrangement sequences that, up to date, have a GI close to 98 %, where caution is warranted.
Institute of Applied Biosciences, Center for Research and Technology Hellas, Thessaloniki, Greece.
Aliki
A
Xochelli
Andreas
A
Agathangelidis
Ioannis
I
Kavakiotis
Evangelia
E
Minga
Lesley Ann
LA
Sutton
Panagiotis
P
Baliakas
Ioanna
I
Chouvarda
Véronique
V
Giudicelli
Ioannis
I
Vlahavas
Nikos
N
Maglaveras
Lisa
L
Bonello
Livio
L
Trentin
Alessandra
A
Tedeschi
Panagiotis
P
Panagiotidis
Christian
C
Geisler
Anton W
AW
Langerak
Sarka
S
Pospisilova
Diane F
DF
Jelinek
David
D
Oscier
Nicholas
N
Chiorazzi
Nikos
N
Darzentas
Fred
F
Davi
Paolo
P
Ghia
Richard
R
Rosenquist
Anastasia
A
Hadzidimitriou
Chrysoula
C
Belessi
Marie-Paule
MP
Lefranc
Kostas
K
Stamatopoulos
D000483:Alleles; D000595:Amino Acid Sequence / Q000235:genetics; D022801:Complementarity Determining Regions / Q000235:genetics*; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics* / Q000276:immunology* / Q000473:pathology; D009154:Mutation; D011379:Prognosis; D016415:Sequence Alignment
D022801:Complementarity Determining Regions