Extensive clinical, serologic and molecular studies lead to the first reported Rhmod phenotype in Argentina
- 6 May 2020
- journal article
- research article
- Published by Wiley in Transfusion
- Vol. 60 (7), 1373-1377
- https://doi.org/10.1111/trf.15792
Abstract
BACKGROUND A highly reduced expression of Rh antigens in the erythrocyte membrane is the main feature of Rhmod, an extremely rare phenotype. Mutations within RHAG gene, which encodes RhAG glycoprotein and modulates Rh antigen expression and Rh complex formation, are the molecular events responsible for the Rhmod phenotype. Here we report a clinical, serologic, and molecular study of an Argentinean proband with Rh‐deficiency syndrome. MATERIALS AND METHODS Rh antigens, RhAG and CD47 glycoproteins were studied by serologic methods in the proband, her parents and sister. Osmotic fragility and viscoelastic parameters were also examined. RHD zygosity was analyzed by RFLP‐PCR. RHD, RHCE, and RHAG genes were studied by Sanger sequencing. RESULTS No Rh antigens were detected in the proband by standard techniques. However, adsorption‐elution and anti‐RhAG tests showed that the proposita was Rhmod. Reduced expression of CD47, enhanced osmotic fragility, and surface viscosity alterations giving rise to spherocytes were observed in the patient. Sequencing analysis showed that a c.920C>T mutation in RHAG Exon 6 was present in a homozygous state in the proband and in a heterozygous state in the rest of the family. This novel missense mutation caused the p.Ser307Phe amino acid substitution in Transmembrane Segment 10 of the RhAG glycoprotein. CONCLUSION This comprehensive study determined the causes of the probandʼs anemia allowing the diagnosis of Rh‐deficiency syndrome.Funding Information
- Agencia Nacional de Promoción Científica y Tecnológica (PICT 2015‐2324)
- Consejo Nacional de Investigaciones Científicas y Técnicas
- Fundação de Amparo à Pesquisa do Estado de São Paulo
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