Study on the Bw11 subtype caused by the 695 T>C mutation in exon 7 of the ABO blood group gene

doi:10.16150/j.1671-2870.2024.04.007

Abstract

Abstract:

Objective To identify the rare ABO*BW.11/ABO*O.01.02 subtype in the Yi ethnic group in China, and to investigate the blood group serological characteristics, molecular mechanisms, and genetic background of the ABO*BW.11/ABO*O.01.02 subtype. Methods The proband was a 25-year-old pregnant woman, with ABO typing discre-pancy in routine tests on admission. Due to the inability to accurately identify the conventional ABO blood serology, exons 1-7 of the ABO gene were analyzed by sequencing using the Sanger method, and the effect of the mutation at this site on the structure and function of B glycosyltransferase was predicted using the amino acid series homology modelling of wild-type B glycosyltransferase. Results The blood group serological results of the proband and lineage were inconsistent with the typical B subtype. ABO gene sequencing unveiled a c.695T>C missense mutation in exon 7 of the ABO blood group gene in the 7 probands and family members in 4 generations, leading to the substitution of leucine by proline at position 232 of the B glycosyltransferase. Homology modeling showed that the mutation influenced the peptide and hydrogen bonds of the protein, which probably led to structural and functional alterations, diminished B-glycosyltransferase activity, and weakened expression of the B antigen. Conclusions This proband carries a point mutation in the ABO allele in exon 7 c.695T>C.P.leu 232 Pro to form the ABO*BW.11/ABO*O.01.02 subtype, and is stably inherited in multiple members of this family.

Key words: ABO subtype, gene mutation, B_w isoform, B glycosyltransferase

CLC Number:

R446.1

ZHOU Lihua, SHEN Ru, QU Kexuan, WANG Aihua, CHEN Youhui, YUAN Zhimin. Study on the B_w11 subtype caused by the 695 T>C mutation in exon 7 of the ABO blood group gene[J]. Journal of Diagnostics Concepts & Practice, 2024, 23(04): 392-397.

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References 16

[1]	雷航, 范亮峰, 蔡晓红, 等. 中国人群血型ABO亚型的分子基础研究[J]. 诊断学理论与实践, 2020, 19(4):364-369.
	LEI H, FAN L F, CAI X H, et al. The study on molecular basis of ABO blood subgroups in the Chinese population[J]. J Diagn Concepts Pract, 2020, 19(4):364-369.
[2]	许先国, 洪小珍, 吴俊杰, 等. α-1,3-N-乙酰半乳糖胺基转移酶等位基因467C>T和539G>C变异导致A2亚型[J]. 中国实验血液学杂志, 2006, 14(4):808-811.
	XU X G, HONG X Z, WU J J, et al. Variants 467C>T and 539G>C of the α-1,3-N-acetylgalactosaminyltransferase Allele Responsible for A2 Subgroup[J]. Chin J Exp Hematol, 2006, 14(4):808-811.
[3]	尚红主编. 全国临床检验操作规程(第四版)[M]. 北京: 人民卫生出版社, 2014:118-126.
	Shang H (Editor). National Clinical Laboratory Operating Procedures(4th Edition)[M]. Beijing: People's Medical Publishing House, 2014:118-126.
[4]	孔永奎, 蔡晓红, 王莉, 等. 一例ABO血型Aw33亚型新等位基因的分子生物学鉴定[J]. 中华医学遗传学杂志, 2020, 37(5):570-572.
	KONG Y K, CAI X H, WANG L, et al. Characterization of a novel allele of Aw33 subtype of the ABO blood group[J]. Chin J Med Genet, 2020, 37(5):570-572.
[5]	梁海英, 王雅丽, 刘铁梅, 等. Bm亚型鉴定及家系调查分析[J]. 中国实验诊断学, 2018, 22(11):1974-1975.
	LIANG H Y, WANG Y L, LIU T M, et al. Identification of Bm subtype and family investigation analysis[J]. Chin J Lab Diagn, 2018, 22(11):1974-1975.
[6]	HOSSEINI-MAAF B, LETTS J A, PERSSON M, et al. Structural basis for red cell phenotypic changes in newly identified, naturally occurring subgroup mutants of the human blood group B -glycosyltransferase[J]. Transfusion, 2007, 47(5):864-875.
[7]	LEE S Y, IHM C, SHIN D J, et al. The p.R168Q mutation is associated with the Bw phenotype and a predicted decrease in the stability of the resulting ABO glycosyltransferase[J]. Transfusion, 2014, 54(5):1298-1304. doi: 10.1111/trf.12461 pmid: 24898455
[8]	孙文杰, 何婷, 韩军, 等. 20例ABO血型抗原表达异常样本的血型基因分析[J]. 南方医科大学学报, 2021, 41(9):1431-1435. doi: 10.12122/j.issn.1673-4254.2021.09.21
	SUN W J, HE T, HAN J, et al. Genetic analysis of weakened expression of ABO blood group antigen in 20 cases[J]. J South Med Univ, 2021, 41(9):1431-1435.
[9]	CAI X, QIAN C, WU W, et al. An exonic missense mutation c.28G>A is associated with weak B blood group by affecting RNA splicing of the ABO gene[J]. Transfusion, 2017, 57(9):2140-2149.
[10]	冯晨晨, 任伟超, 程道胜, 等. Bw11亚型家系表现ABO等位基因竞争现象的研究[J]. 中华医学遗传学杂志, 2021, 38(1):23-26.
	FENG C C, REN W C, CHENG D S, et al. Investigation of ABO Allelic Competition phenomena in a pedigree with Bw11 Subtype[J]. Chin J Med Gene, 2021, 38(1):23-26.
[11]	马晓莉, 马宏伟, 金新莉, 等. 基因分型结合血清学方法鉴定ABO血型亚型[J]. 中国输血杂志, 2018, 31(2):151-153.
	MA X L, MA H W, JIN X L, et al. ABO blood subgroup identification with serological methods assisted by genotyping[J]. Chin J Blood Transfus, 2018, 31(2):151-153.
[12]	赵桐茂. 基因分型预测ABO亚型的局限性[J]. 临床输血与检验, 2018, 20(2):113-116. doi: 10.3969/j.issn.1671-2587.2018.02.001
	ZHAO T M. Limitations of ABO Genotyping for Prediction of ABO Subtypes[J]. Clin Transfus Lab Med, 2018, 20(2):113-116.
[13]	Bugert P, Scharberg E A, Janetzko K, et al. A novel variant B allele of the ABO blood group gene associated with lack of b antigen expression[J]. Transfus Med Hemother, 2008, 35(4):319-323.
[14]	喻琼, 吴国光, 梁延连, 等. 一个中国汉族ABO血型B亚型家系中发现新的B等位基因[J]. 中华医学遗传学杂志, 2005, 22(2):129-133.
	YU Q, WU G G, LIANG Y L, et al. Identification of a novel B variant allele in a Chinese Han individual with B Subgroup[J]. Chin J Med Gene, 2005, 22(2):129-133.
[15]	YING Y, HONG X, XU X, et al. Mechanism evaluation for an amino acid substitution p.Y246C of B-glycosyltransferase enzyme with Bweak phenotype[J]. Vox Sang, 2021, 116(4):464-470. doi: 10.1111/vox.13041 pmid: 33326610
[16]	SELTSAM A, GRÜGER D, JUST B, et al. Aberrant intracellular trafficking of a variant B glycosyltransferase[J]. Transfusion, 2008, 48(9):1898-1905. doi: 10.1111/j.1537-2995.2008.01782.x pmid: 18513251

Primers for sequencing exons 1-7 of the ABO gene	Primer sequences(5′→3′)	Fragment (Size)
EXON1		818 bp
1Forward	CGGGGATCGTGGGTTCTG
1Reverse	GGGCGGTAGGTGCTGAAAAT
EXON2		286 bp
1Forward	AAGGCGGGACAGGTAAAGT
1Reverse	GCTGGACGCAGGCAATAA
EXON3		297 bp
1Forward	GAGGAAGGGACCAACAGG
1Reverse	GACTCCAGAGGTATCCAGGTG
EXON4		391 bp
1Forward	GCTTCGACGTGTCTGGTGA
1Reverse	CACATGTGCCAGGGCTGCAG
EXON5		972 bp
1Forward	GATGTCCTCACGGTCCATCC
1Reverse	GAACAAAGGGTCAGGAAACAAG
EXON6		545 bp
1Forward	GGAGGGTTTGTTCCTATCTCT
1Reverse	TGACCTTTCCCATCTACCCTCT
EXON7		911 bp
1Forward	GTGGTGCATCTGCTGCTCTAA
1Reverse	GGACGGACAAAGGAAACAGAGTT

Sample No.	Title	Forward typing		Reverse typing			Additional testing
Sample No.	Title	Anti-A	Anti-B	A1c	BC	Oc	Anti-AB	Anti-H	Self-control
1	Proband	0	2+	2+	1+	0	0	4+	0
2	Sister	0	2+	2+	1+	0	0	4+	0
3	Uncle	0	2+	3+	1+	0	0	4+	0
4	Aunt	0	2+	2+	1+	0	0	4+	0
5	Elder male cousin	0	2+	3+	1+	0	0	4+	0
6	Brother's son	0	2+	2+	1+	0	0	4+	0
7	Grandma	0	2+	2+	1+	0	0	4+	0