AUTHOR=Dambietz Christine Anna , Doescher Andrea , Heming Michael , Schirmacher Anja , Schlüter Bernhard , Schulte-Mecklenbeck Andrea , Thomas Christian , Wiendl Heinz , Meyer zu Hörste Gerd , Wiethoff Sarah
TITLE=Case report: Clinical, genetic and immunological characterization of a novel XK variant in a patient with McLeod syndrome
JOURNAL=Frontiers in Genetics
VOLUME=15
YEAR=2024
URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2024.1421952
DOI=10.3389/fgene.2024.1421952
ISSN=1664-8021
ABSTRACT=Introduction: Pathogenic variants in the XK gene are associated with dysfunction or loss of XK protein leading to McLeod syndrome (MLS), a rare X-linked neuroacanthocytosis syndrome with multisystemic manifestation. Here we present clinical, genetic and immunological data on a patient originally admitted to our clinic for presumed post-COVID-19 syndrome, where thorough clinical work-up revealed a novel frameshift deletion in XK causal for the underlying phenotype. We additionally review the clinicogenetic spectrum of reported McLeod cases in the literature.
Methods: We performed in-depth clinical characterization and flow cytometry of cerebrospinal fluid (CSF) in a patient where multi-gene panel sequencing identified a novel hemizygous frameshift deletion in XK. Additionally, Kell (K) and Cellano (k) antigen expression was analysed by Fluorescence-activated Cell Sorting (FACS). KEL gene expression was examined by RNA sequencing.
Results: A novel hemizygous frameshift deletion in the XK gene resulting in premature termination of the amino acid chain was identified in a 46-year old male presenting with decrease in physical performance and persisting fatigue after COVID-19 infection. Examinations showed raised creatine kinase (CK) levels, neuropathy and clinical features of myopathy. FACS revealed the K-k+ blood type and reduced Cellano density. CSF flow cytometry showed elevation of activated T Cells.
Conclusion: In-depth clinical, genetic, immunological and ribonucleic acid (RNA) expression data revealed axonal neuropathy, myopathy and raised levels of activated CSF-T-lymphocytes in a patient with a previously unpublished frameshift deletion in the XK gene.