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Reply to ‘hRap1B-retro: a novel human processed Rap1B gene blurs the picture?’ by Zemojtel et al

Leukemia volume 20, pages 146–147 (2006)Cite this article

We agree with the comments made by Zemojtel et al.1 and we thank them very much for the proposed hypothesis. In our work published in the September issue of Leukemia,2 we initially used previously published oligonucleotides3 to analyze rap1b transcript in bone marrow samples from 27 patients with myelodysplastic syndromes (MDS) and two secondary acute myeloid leukemias (sAML). In one patient with RARS and abnormal karyotype (45, XX, −7/46, XX (19/1)), we observed two substitutions as compared to rap1b cDNA published sequence, which we interpreted as two amino-acid substitutions in G12R and K42E in Rap1B protein. We then analyzed rap1b genomic DNA by using denaturating gradient gel electrophoresis. At that time, we were aware of the presence of a sequence highly homologous to rap1b corresponding to a pseudogene located on chromosome 5q13.3 and, in order to avoid the amplification of this pseudogene, we designed oligonucleotides located in the intronic sequences of rap1b on chromosome 12, including one pair specific for exon 2 and another one to amplify exon 3. Using this strategy, we did not identify any rap1b gene mutation in genomic DNA of 56 MDS patients tested. Unfortunately, DNA from the patient in whom we had identified substitutions in cDNA was not available for genomic analysis.

The rap1b pseudogene on chromosome 5q13.3 is a retrotransposon (hRap1B-retro) with two exons expected to lack intronic sequences. As indicated by Zemojtel and co-workers, an intronic sequence is actually created by insertion of a SVA sequence in the retrogene. Evidence for the transcription of this retrogene is provided by the fact that the corresponding cDNAs in the database are devoid of the intronic sequence. At the time we prepared our manuscript, we missed this information.

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References

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Acknowledgements

We thank Dr J. Andrieux, CHRU Lille, who provided 12q14 BAC and Dr F. Viguié from Hotel-Dieu (Paris) for cytogenetic analysis.

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Authors and Affiliations

  1. Departement d'Hematologie, Institut Cochin INSERM U567, CNRS UMR 8104, Universite Rene-Descartes, Paris, France

    E Gyan, F Porteu & M Fontenay

  2. Service d'Hématologie Biologique, Hôpital Cochin, AP-HP, Paris, France

    M Fontenay

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  1. E Gyan
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  2. F Porteu
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  3. M Fontenay
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Gyan, E., Porteu, F. & Fontenay, M. Reply to ‘hRap1B-retro: a novel human processed Rap1B gene blurs the picture?’ by Zemojtel et al. Leukemia 20, 146–147 (2006). https://doi.org/10.1038/sj.leu.2404042

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