Acquired immunodeficiency syndrome (AIDS) is a chronic, potentially life-threatening condition caused by the human immunodeficiency virus (HIV). By damaging your immune system, HIV interferes with your body's ability to fight infection and disease

Coeliac disease is a condition where your immune system attacks your own tissues when you eat gluten. This damages your gut (small intestine) so you are unable to take in nutrients. Coeliac disease can cause a range of symptoms, including diarrhoea, abdominal pain and bloating.

Vitiligo is a condition in which the skin loses its pigment cells (melanocytes). This can result in discolored patches in different areas of the body, including the skin, hair and mucous membranes. Vitiligo (vit-ih-LIE-go) is a disease that causes loss of skin color in patches.

Fibromyalgia is a disorder characterized by widespread musculoskeletal pain accompanied by fatigue, sleep, memory and mood issues. Researchers believe that fibromyalgia amplifies painful sensations by affecting the way your brain and spinal cord process painful and nonpainful signals.

Hives is a common skin rash triggered by many things, including certain foods, medication and stress. Symptoms include itchy, raised, red or skin-coloured welts on the skin's surface. Hives usually go away without treatment, but antihistamine medication is often helpful in improving symptoms.

Lupus (SLE) can affect the joints, skin, kidneys, blood cells, brain, heart and lungs. Symptoms vary but can include fatigue, joint pain, rash and fever. These can periodically get worse (flare up) and then improve. While there's no cure for lupus, current treatments focus on improving quality of life through controlling symptoms and minimising flare-ups. This begins with lifestyle modifications, including sun protection and diet. Further disease management includes medication such as anti-inflammatories and steroids.

A goitre (sometimes spelled "goiter") is a swelling of the thyroid gland that causes a lump in the front of the neck. The lump will move up and down when you swallow. Credit: The thyroid gland is a small butterfly-shaped gland in the neck, just in front of the windpipe (trachea).

In MS, resulting nerve damage disrupts communication between the brain and the body. Multiple sclerosis causes many different symptoms, including vision loss, pain, fatigue and impaired coordination. The symptoms, severity and duration can vary from person to person. Some people may be symptom free for most of their lives, while others can have severe, chronic symptoms that never go away. Physiotherapy and medication that suppress the immune system can help with symptoms, and slow disease progression.

Parkinson's disease is a brain disorder that leads to shaking, stiffness, and difficulty with walking, balance, and coordination. Parkinson's symptoms usually begin gradually and get worse over time. As the disease progresses, people may have difficulty walking and talking.

Sarcoidosis is a disease characterized by the growth of tiny collections of inflammatory cells (granulomas) in any part of your body — most commonly the lungs and lymph nodes. But it can also affect the eyes, skin, heart and other organs.

Sickle cell anemia is an inherited red blood cell disorder in which there aren't enough healthy red blood cells to carry oxygen throughout your body. Normally, the flexible, round red blood cells move easily through blood vessels. In sickle cell anemia, the red blood cells are shaped like sickles or crescent moons.

The thyroid is a butterfly-shaped gland that sits low on the front of the neck. Your thyroid lies below your Adam's apple, along the front of the windpipe. The thyroid has two side lobes, connected by a bridge (isthmus) in the middle.

Ulcerative colitis (UL-sur-uh-tiv koe-LIE-tis) is an inflammatory bowel disease (IBD) that causes inflammation and ulcers (sores) in your digestive tract. Ulcerative colitis affects the innermost lining of your large intestine (colon) and rectum. Symptoms usually develop over time, rather than suddenly.

Diabetes is a disease that occurs when your blood glucose, also called blood sugar, is too high. Blood glucose is your main source of energy and comes from the food you eat. Insulin, a hormone made by the pancreas, helps glucose from food get into your cells to be used for energy.

Atopic dermatitis (eczema) is a condition that makes your skin red and itchy. It's common in children but can occur at any age. Atopic dermatitis is long lasting (chronic) and tends to flare periodically. It may be accompanied by asthma or hay fever. No cure has been found for atopic dermatitis.

Psoriasis is a skin disease that causes red, itchy scaly patches, most commonly on the knees, elbows, trunk and scalp. Psoriasis is a common, long-term (chronic) disease with no cure. It tends to go through cycles, flaring for a few weeks or months, then subsiding for a while or going into remission.

Ankylosing spondylitis is an inflammatory disease that, over time, can cause some of the bones in the spine (vertebrae) to fuse. This fusing makes the spine less flexible and can result in a hunched posture. If ribs are affected, it can be difficult to breathe deeply.

Rheumatoid arthritis, or RA, is an autoimmune and inflammatory disease, which means that your immune system attacks healthy cells in your body by mistake, causing inflammation (painful swelling) in the affected parts of the body. RA mainly attacks the joints, usually many joints at once.

Myasthenia gravis (my-us-THEE-nee-uh GRAY-vis) is characterized by weakness and rapid fatigue of any of the muscles under your voluntary control. It's caused by a breakdown in the normal communication between nerves and muscles.