Patients usually present with bloody diarrhoea, abdominal pain, weight loss, and fatigue, and the diagnosis is based on a combination of clinical and laboratory findings, such as abnormalities in the complete blood count (leucocytosis, anaemia, and thrombocytosis), elevated C-reactive protein (CRP), elevated faecal calprotectin, hypoalbuminemia, and micronutrient deficiencies. This evidence concerns the gene CRP and thrombocytosis disease.