Objective: to analyze the stereotyped subsets in cohort of Ukrainian chronic lymphocytic leukemia (CLL) patients in general and depending on the ionizing radiation (IR) exposure.
Methods: Analysis was performed in the groups of 118 CLL patients irradiated due to the Chornobyl NPP accident (95 clean-up workers, 17 inhabitants of radionuclide contaminated areas, and 6 evacuees) and 294 IR non-exposed patients. The IGHV (immunoglobulin heavy chain variable region) gene mutational status, mutations of NOTCH1, TP53 and SF3B1 genes were studied by polymerase chain reaction followed by direct sequencing. Associations between clinical and molecular data of patients were analyzed with the SPSS software package, version 20.0.
Results: The incidence of stereotyped CLL cases in Ukrainian cohort was high (50.5 %) and comparable in IR-exposed and non-exposed patients. The ratio of major and minor clusters as well as the frequency of individual clusters was comparable with reported data with some exceptions: a low incidence of subset #2; absence of subset #8; high frequency of minor subset #V4|J4.5.6|18|5. The distinctive features of IR-exposed CLL patients found were:1) comparable frequency of stereotyped cases among mutated and unmutated (UM) IGHV genes cases (p = 0.557);2) lack of differences IGHV gene repertoires among stereotyped and heterogeneous cases (p = 0.508); 3) «heterogeneity» of stereotyped cases: all identified stereotyped clusters, with the exception of cluster #1, consisted of one case. Stereotyped cases with expression of UM IGHV clan I genes (except IGHV1-69 gene) were more susceptible to the appearance of NOTCH1 mutations. Patients of cluster #4 were younger, tended to have a longer time-to-treatment period and overall survival (OS) compared to subset #2. Patients of cluster #2 are more likely to have autoimmune hemolytic anemia (AIHA) and SF3F1 mutations. IGHV3-21 expression was associated with worse OS in univariate and multivariate analysis. AIHA was more common in patients with UM IGHV4-59 and IGHV3-11 genes.
Conclusions: The revealed differences in distribution of stereotyped CLL cases in Ukrainian cohort are most likely to reflect variations in the genetic background, environmental factors (including IR exposure), and their interactions in different geographic areas.
Meta: porivnial'nyĭ analiz chastoty ta spektru stereotypnykh klasteriv u kogorti ukraïns'kykh khvorykh na khronichnu limfotsytarnu leĭkemiiu (KhLL) z urakhuvanniam naiavnosti v anamnezi vplyvu ionizuiuchogo vyprominiuvannia. Metody. Doslidzhennia provedeno v grupi 118 khvorykh na KhLL, oprominenykh vnaslidok avariï na Chornobyl's'kiĭ AES (95 uchasnykiv likvidatsiï naslidkiv avariï 1986 r., 17 meshkantsiv terytoriĭ, kontaminovanykh radionuklidamy, 6 evakuĭovanykh) i v grupi 294 neoprominenykh khvorykh. Mutatsiĭnyĭ status geniv vazhkykh lantsiugiv imunoglobuliniv (IGHV geniv), mutatsiï geniv NOTCH1, TP53 i SF3B1 doslidzhuvaly za dopomogoiu polimeraznoï lantsiugovoï reaktsiï z nastupnym sekvenuvanniam. Asotsiatsiï mizh klinichnymy i molekuliarnymy danymy analizuvaly u statystychniĭ programi SPSS software package, version 20.0.Rezul'taty. Chastota stereotypnykh vypadkiv v ukraïns'kiĭ KhLL kogorti bula vysokoiu (50,5 %) i ne rozriznialas' sered oprominenykh ta neoprominenykh khvorykh. Spivvidnoshennia mazhornykh i minornykh klasteriv, a takozh chastota okremykh klasteriv buly skhozhymy z danymy literatury za dekil'koma vyniatkamy: nyz'ka chastota klastera #2;vidsutnist' klastera #8; vysoka chastota minornogo klastera #V4|J4.5.6|18|5. Osoblyvostiamy oprominenykh khvorykh buly: 1) odnakova chastota stereotypnykh klasteriv sered vypadkiv KhLL z mutovanymy i nemutovanymy (UM) IGHV genamy (p = 0,557); 2) vidsutnist' dostovirnykh rozbizhnosteĭ v repertuari IGHV geniv sered stereotypnykh i geterogennykh vypadkiv (p = 0,508); 3) «geterogennist'» stereotypnykh vypadkiv: vsi identyfikovani klastery, za vyniatkom klasteru #1, buly predstavleni odnym vypadkom. Sered stereotypnykh vypadkiv z ekspresiieiu UM IGHV geniv I klanu (krim gena IGHV1-69) chastishe zustrichalys' mutatsiï gena NOTCH1. Khvori, iaki nalezhaly do klasteru #4, porivniano z patsiientamy klasteru #2, buly molodshymy, maly tendentsiiu do zbil'shennia periodu do pochatku terapiï ta zagal'nogo vyzhyvannia. Sered khvorykh klasteru #2 chastishe diagnostuvaly autoimunnu gemolitychnu anemiiu ta mutatsiï gena SF3F1. Ekspresiia gena IGHV3-21 bula asotsiĭovana z nyz'kymy pokaznykamy zagal'nogo vyzhyvannia pry uni- ta mul'tyvariantnomu regresiĭnomu analizi. Autoimunna gemolitychna anemiia chastishe zustrichalas' u khvorykh z ekspresiieiu UM IGHV4-59 i IGHV3-11 geniv.Vysnovky. Vyiavleni rozbizhnosti rozpodilu stereotypnykh vypadkiv v ukraïns'kiĭ kogorti khvorykh na KhLL naĭbil'sh virogidno vidobrazhaiut' vplyv genetychnykh faktoriv, faktoriv navkolyshn'ogo seredovyshcha (vkliuchaiuchy ĭ ionizuiuche vyprominiuvannia), ta ïkh vzaiemodiiu u pevniĭ geografichniĭ zoni.
Keywords: Chornobyl NPP accident; IGHV genes; chronic lymphocytic leukemia; stereotyped subsets.
N. I. Bilous, I. V. Abramenko, A. A. Chumak, I. S. Dyagil, Z. V. Martina.