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CASE REPORT
False homozygous HLA genotyping results due to copy number neutral loss of heterozygosity in acquired aplastic anaemia
  1. Bert Heyrman1,
  2. Ann De Becker1,
  3. Sonja Verheyden2,
  4. Christian Demanet2
  1. 1Department of Hematology, Universitair Ziekenhuis Brussels, Brussels, Belgium
  2. 2Department of Molecular Hematology, Universitair Ziekenhuis Brussels, Brussels, Belgium
  1. Correspondence to Dr Bert Heyrman, bertheyrman{at}gmail.com

Summary

The aim of this case report is to draw attention on possible false human leucocyte antigen (HLA) genotyping in acquired aplastic anaemia prior to allogeneic haematopoietic stem cell transplantation. In acquired aplastic anaemia loss of heterozygosity (LOH) of chromosome 6p is known to occur in around 12%. We report false HLA genotyping results due to LOH and a coinciding steep rise in neutrophils following filgrastim stimulation in a patient with very severe aplastic anaemia. At diagnosis we obtained heterozygous results on peripheral blood. Failing to reach a partial response at 6 months with immune-suppressive therapy we repeated HLA genotyping, obtaining homozygous results. Repeated testing confirmed loss of HLA genotype heterozygosity. HLA genotyping on cells obtained by a buccal swab confirmed the previous HLA heterozygosity. A second course of filgrastim at the time of homozygous HLA genotyping resulted in a steep rise in neutrophils. Stopping filgrastim resulted in an equally steep drop.

https://doi.org/10.1136/bcr-2016-217867

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    Footnotes

    • Contributors The first author was responsible for literature research and writing the manuscript. ADB supervised the clinical follow-up of the patient. SV is responsible for all HLA testing. CD noticed the discrepancy between the new and earlier HLA results and motivated to write this manuscript. All co-authors were equally involved in critically revising and editing the manuscript. The final version was approved by all authors.

    • Competing interests None declared.

    • Patient consent Obtained.

    • Provenance and peer review Not commissioned; externally peer reviewed.