A proposed clinical tool to identify high-risk patients for monogenic lupus: a pilot study.

Objectives: To develop an easy-to-use and efficient clinical score to identify monogenic lupus based on clinical presentations and to stratify patients who may benefit from confirmatory molecular genetic testing.

Methods: A comprehensive literature review identified 55 distinct items across 12 clinical and laboratory domains, narrowed down to the top ten by a panel of 12 expert paediatric rheumatologists with 80% consensus. The proposed score was tested in a pilot study on 10 patients with monogenic lupus and 30 control subjects with various autoimmune and autoinflammatory diseases. All patients, both with monogenic lupus and the control group, were then scored, and a receiver operating characteristic curve was employed to determine the threshold that distinguishes monogenic lupus from non-monogenic lupus.

Results: The clinical score comprised 10 items. Among all patients, the most frequent items were antinuclear antibody positivity and consanguinity, followed by early disease onset (<5 years), with no significant differences between monogenic lupus patients and the controls. However, the monogenic lupus patients exhibited significantly higher rates of family history of lupus, failure to thrive, cutaneous lesions, brain imaging changes, a low C1q level, and recurrent infections. Also, they achieved the highest scores compared to the controls. A score of more than three was found to be highly predictive for diagnosing monogenic lupus, with a sensitivity of 90% and a specificity of 90%.

Conclusions: Our clinical score appears to be a valuable tool for the early identification of patients with monogenic lupus who may require further molecular genetic testing for confirmation.