A thorough literature search using Google Scholar as the search engine and using keywords such as 'absolute lymphocyte count', 'CD3 negative natural killer cells', 'CD56 natural killer cells', 'CD16 natural killer cells', 'systemic lupus erythematosus', and 'ROC curve' did not reveal any studies giving a cut-off value with sensitivity and specificity. The gene discussed is NCAM1; the disease is systemic lupus erythematosus.