This study looks at coeliac disease, a condition where eating gluten (a protein in wheat) can cause the immune system to attack the small intestine. It also examines dermatitis herpetiformis, a skin rash linked to coeliac disease. Scientists want to learn why people with these conditions have different symptoms and find better ways to predict and manage them. They will study genes, immune responses, and gut bacteria.

To be part of this study, you must either have coeliac disease or dermatitis herpetiformis, or be a healthy friend or family member of someone with these conditions. You cannot participate if you're under 18, have not been officially diagnosed, or have a diagnosis if you're supposed to be a healthy control.

• The research aims to improve personalized treatment for coeliac disease.
• Participants may need to undergo genetic and medical tests.
• No compensation details are provided, but the study may help future treatments.