First report of Rh<sub>null</sub> individuals in the Indian population and characterization of the underlying molecular mechanisms

Kulkarni, Shrikant; Vasantha, K; Gogri, Harita; Parchure, Disha; Madkaikar, Manisha; Férec, Claude; Fichou, Yann

doi:10.1111/trf.14150

Cited by 4 publications

(5 citation statements)

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“…From the data available in the literature, it is thought to be the eleventh intronic SNV in RHCE affecting splicing (Table 2). In RHCE , in addition to the novel variant presented here, only c.634+1G>T, 20 c.1074‐2A>G, 17 and c.801+1G>A 21 have been formally shown to alter splicing by functional analysis so far. At the transcriptional level, c.634+4A>G promotes inclusion of two abnormal products longer than and in addition to the full‐length exon within the transcript.…”

Section: Discussionmentioning

confidence: 71%

The novel c.634+4A>G splicing variant inRHCEresults in weak C and e antigen expression in a pregnant woman originated from Japan

et al. 2022

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Background: In the RH blood group genes, molecular variants that alter antigen expression with potential clinical relevance are frequently identified and reported in the literature. Study Design and Methods: A pregnant woman in her first pregnancy, who originates from Japan, was typed by routine serological testing. The RHCE gene was investigated to identify single nucleotide variants (SNVs) and/or structural variants by a commercial platform, Sanger sequencing, and quantitative multiplex PCR of short fluorescent fragments. The haplotypes were determined by sequencing PCR fragments generated from genomic DNA and subcloned into a plasmid vector. Effect on splicing was predicted by bioinformatics tools, including SpliceAI and the splicing module of Alamut. In parallel, functional analysis was carried out by a minigene splicing assay. Results: A patient with no transfusion history was typed RH:1,2w,3,4,5w. An unreported single variant was identified in RHCE intron 4 at the heterozygous state: c.634+4A>G. Minigene splicing assay showed that this SNV decreases significantly the relative abundance of the full-length transcript, in accordance with the predictions made by the Alamut tools, but not SpliceAI, suggesting expression of a normal RhCE protein. Conclusion:Overall, the novel RHCE*02(c.634+4A>G) allele alters quantitatively, but not qualitatively, the expression of C and e in the RH blood group system, indicating that the patient is not at risk for alloimmunization and may safely receive C+e+ red blood cell units. This report illustrates the relevance of functional assays for the interpretation of rare variants and, specifically, how it may help guide transfusion management in patients.

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Section: Discussionmentioning

confidence: 71%

The novel c.634+4A>G splicing variant inRHCEresults in weak C and e antigen expression in a pregnant woman originated from Japan

et al. 2022

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“…This system comprises two highly homologous genes, namely, RHD and RHCE , encoding RhD and RhCE antigens expressed on the surface of red blood cells (RBCs) (Daniels, ). The RhAG antigen, which currently belongs to the RhAG system (ISBT 030), is highly associated with the Rh system because it can affect the expression of Rh antigens on RBCs (Tilley et al, ; Daniels, ; Polin et al, ; Kulkarni et al, ).…”

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confidence: 99%

“…The Rh null phenotype arises from two distinct genetic mechanisms, which are of amorph and regulator types. The amorph type is caused by homozygosity mutations in RHD and RHCE , resulting in their inactivated forms; in contrast, the regulator type is caused by a mutation in RHAG in homozygous situations or with another RHAG allele containing an inactivating mutation in heterozygous situations, but the RHD and RHCE of Rh null regulator type are normal (Tilley et al, ; Polin et al, ; Kulkarni et al, ). The gene background of Rh mod is similar to that of Rh null regulator type; thus, RHD and RHCE of Rh mod are normal, and mutations exist in RHAG (Tilley et al, ).…”

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A novel double‐variant RHAG allele leads to Rh_mod phenotype

Xia

Chen

Zhang

et al. 2019

Transfusion Medicine

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Aims/Objectives:We aimed to analyse the molecular backgrounds and red blood cell (RBC) antigen expression of a male blood donor with Rh mod phenotype and his family members.Background: Rh deficiency phenotypes are rarely found worldwide and are characterised by the lack of Rh antigen expression on RBCs. During routine screening, we found a blood donor who seemingly lacked Rh antigens. Therefore, we recruited the donor and his family for further investigation. Methods:RBC serotyping and antibody screening/identification were performed for each sample. A routine blood examination was also conducted. RHD, RHCE and RHAG were sequenced at the genomic DNA or RNA level. Eleven antigens or proteins associated with Rh complex were tested using flow cytometry analysis. Results:The proband and one of his brothers showed extremely weak D antigen and Rh expression levels but did not manifest anaemia. Most of the expressed RBC antigens of the two Rh-deficient individuals were similar to the previously reported cases but with some exceptions. Molecular analyses demonstrated homozygous expression of a novel RHAG allele, namely, c.[572G>A;707A>C], both in the proband and one of his brothers. Conclusions:To our knowledge, we identified the second double-variant RHAG allele and the first one related to Rh mod phenotype. The novel allele was also confirmed to be heritable by family analyses.

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“…[3][4][5] Conditions caused by the former are called amorph type and by the latter the regulator type. 6 Only 18 nucleotide mutations to date have been registered with the International Society of Blood Transfusion (ISBT) as Rh null -associated RHAG blood group alleles, and the mechanisms of regulator-type Rh null phenotypes, and their clinical features are still unclear. In this study, we examined three individuals within two families in the Japanese population who had the same genetic mutation in RHAG, c.945+1G>A (RHAG*01 N.04 ISBT designation).…”

mentioning

confidence: 99%

“…Rh antigen expression depends on the genetic background of either RH‐coding genes ( RhD and RhCE ) or Rh‐associated glycoprotein ( RHAG ) genes . Conditions caused by the former are called amorph type and by the latter the regulator type . Only 18 nucleotide mutations to date have been registered with the International Society of Blood Transfusion (ISBT) as Rh null ‐associated RHAG blood group alleles, and the mechanisms of regulator‐type Rh null phenotypes, and their clinical features are still unclear.…”

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confidence: 99%

Rh_null phenotype caused by a novel RHAG mutation, c.945+1G>A, in the Japanese population

et al. 2019

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BACKGROUND The Rh complex contributes to cell membrane structural integrity of erythrocytes. Rhnull syndrome is characterized by the absence of the Rh antigen on the erythrocyte membrane, resulting in chronic hemolytic anemia. We recently came across 3 Rhnull phenotype probands within two families with the same novel RHAG mutation in the Japanese population. MATERIALS AND METHODS Detailed Rh phenotyping by hemagglutination was performed using monoclonal and polyclonal anti‐D, ‐C, −c, −E, and ‐e; monoclonal and polyclonal anti‐Rh17 antibodies; and polyclonal anti‐Rh29 antibodies. RHAG mRNA transcripts were analyzed by reverse transcription–polymerase chain reaction, and the mutation was verified by genomic sequencing. RESULTS The genomic region spanning exon 6 contained a G > A transition in the invariant GT motif of the 5′ donor splice‐site of Intron 6 (c.945+1G>A). The Rhnull phenotype was caused by an autosomal recessive mutation in Probands 1 and 2, determined by family history. Regarding clinical features, the degree of hemolysis varied slightly between these individuals, with Proband 3 displaying acute hemolytic anemia with an infection. While no standard therapy has been established, the condition of the patient in this study improved with conservative treatment, including hydration and antibiotics. CONCLUSION The mechanisms of hemolysis due to the Rhnull phenotype can vary, but our findings indicate that acute hemolytic crisis caused by the Rhnull syndrome could be associated with infection.

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First report of Rh_null individuals in the Indian population and characterization of the underlying molecular mechanisms

Abstract: Overall, we report for the first time the molecular mechanisms responsible for Rh phenotype in individuals of Indian origin. This study contributes to extend the molecular spectrum of variations in Rh individuals.

Cited by 4 publications

References 26 publications

The novel c.634+4A>G splicing variant inRHCEresults in weak C and e antigen expression in a pregnant woman originated from Japan

The novel c.634+4A>G splicing variant inRHCEresults in weak C and e antigen expression in a pregnant woman originated from Japan

A novel double‐variant RHAG allele leads to Rh_mod phenotype

Rh_null phenotype caused by a novel RHAG mutation, c.945+1G>A, in the Japanese population

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First report of Rhnull individuals in the Indian population and characterization of the underlying molecular mechanisms

Abstract: Overall, we report for the first time the molecular mechanisms responsible for Rh phenotype in individuals of Indian origin. This study contributes to extend the molecular spectrum of variations in Rh individuals.

Cited by 4 publications

References 26 publications

The novel c.634+4A>G splicing variant inRHCEresults in weak C and e antigen expression in a pregnant woman originated from Japan

The novel c.634+4A>G splicing variant inRHCEresults in weak C and e antigen expression in a pregnant woman originated from Japan

A novel double‐variant RHAG allele leads to Rhmod phenotype

Rhnull phenotype caused by a novel RHAG mutation, c.945+1G>A, in the Japanese population

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First report of Rh_null individuals in the Indian population and characterization of the underlying molecular mechanisms

A novel double‐variant RHAG allele leads to Rh_mod phenotype

Rh_null phenotype caused by a novel RHAG mutation, c.945+1G>A, in the Japanese population