Some guidelines recommend investigating serologically weak or discrepant D (RH1) results at the molecular level. This is important not only for transfusions, as anti-D can cause hemolytic transfusion reactions (HTR), but also for women of childbearing potential as anti-D can lead to severe hemolytic disease of the fetus and newborn (HDFN). According to current Swiss transfusion practices, individuals with RHD*01W.1, RHD*01W.2, RHD*01W.3 and RHD*09.04 are treated as D positive. For women of childbearing potential, this means that no prophylactic anti-D is given during pregnancy.
The Rh blood group system has the largest number of variant antigens and alleles. Its genetic diversity and complexity are due to the high homology between the two genes, RHD and RHCE. Molecular blood group diagnostics have become an important tool for the characterization of these RH variants, especially RHD variants.
It all begins with serological D (RH1) determination which helps in categorizing the variant as weak or partial D. Based on the serological pattern, an SSP-PCR kit is chosen. With commercially available kits, the most common RHD variant alleles can be detected. If a common variant is not detected the RHD gene is sequenced either at the DNA or RNA level to identify the underlying RHD variant.
In this webinar, Sofia Lejon Crottet, PhD, will use case studies to show how the most common D variants react serologically and how D characterization is helpful when it comes to choosing the sequence specific (SSP)-PCR kit. She will also present some cases of D variants not detectable by commercially available kits and where DNA or RNA sequencing were needed.
Sofia Lejon Crottet, PhD,
Head of the Swiss National Immunohematology Reference Laboratory
Sofia Lejon Crottet, PhD, is the head the Swiss National Immunohematology Reference Laboratory. After receiving a Master of Science in molecular biology in 2004, she graduated with a PhD in biochemistry in 2008. Before joining the Interregional Blood Transfusion SRC in Bern, Switzerland, she was involved in protein analysis by EIS‐MS, HPLC, amino acid analysis, and Edman sequencing at the Analytical Research and Services, Department of Chemistry and Biochemistry at the University of Bern. She also co-authored a scientific book called “Human Blood Plasma Proteins – Structure and Function” that was published in 2008.
Since 2009, she has worked at the Interregional Blood Transfusion in Bern. She started as a postdoctoral fellow in the Department of Research and Development with a focus on molecular blood group diagnostics and in 2010, she became the deputy head of the laboratory. In 2012, she joined the Swiss National Immunohematology Reference Laboratory as deputy head where she supervised RBC serology and molecular blood group diagnostic activities, reported the results of complex cases, and gave lectures at congresses. Since 2016, she has led and represented the Immunohematology and Reference Laboratory Swiss Transfusion SRC. In addition to investigating and reporting complex cases, she continues to give lectures and share her experience at national events, like the ones organized by the Swiss Association of Transfusion Medicine as well as international congresses such as the ISBT.