Key result
FRET assay detects ~20% lower T cell RNase H2 activity in an RNASEH2C-variant systemic sclerosis patient.
Why the study?
No method for quantification of RNase H2 activity has been validated for the clinical setting.
Observational (n=25)
Absolute Event Rate: 80% vs 100%
A FRET-based whole-cell lysate RNase H2 activity assay was validated for clinical screening, showing acceptable variability and the ability to detect reduced activity in a clinical sample.
Does not support clinical screening for RNase H2 activity in systemic sclerosis; hypothesis-generating for RNASEH2C variants in T-cell dysfunction.
As the key enzyme mediating ribonucleotide excision repair, RNase H2 is essential for the removal of single ribonucleotides from DNA in order to prevent genome damage. Loss of RNase H2 activity directly contributes to the pathogenesis of autoinflammatory and autoimmune diseases and might further play a role in ageing and neurodegeneration. Moreover, RNase H2 activity is a potential diagnostic and prognostic marker in several types of cancer. Until today, no method for quantification of RNase H2 activity has been validated for the clinical setting. Herein, validation and benchmarks of a FRET-based whole-cell lysate RNase H2 activity assay are presented, including standard conditions and procedures to calculate standardized RNase H2 activity. Spanning a wide working range, the assay is applicable to various human cell or tissue samples with overall methodological assay variability from 8.6% to 16%. The assay readily detected reduced RNase H2 activity in lymphocytes of a patient with systemic sclerosis carrying a RNASEH2C variant. Implementation of larger control groups will help to assess the diagnostic and prognostic value of clinical screening for RNase H2 activity in the future.
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Schulz et al. (2022) conducted an observational in Systemic sclerosis (n=25). RNASEH2C c.468G>T variant vs. Healthy controls was evaluated on RNase H2 activity per cell in T cells. A validated FRET-based whole-cell lysate assay detected significantly reduced RNase H2 activity (80% residual activity per cell) in T cells of a systemic sclerosis patient carrying an RNASEH2C variant compared to healthy controls.
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