user: What are the symptoms of Ankylosing spondylitis ?

assistant: What are the signs and symptoms of Ankylosing spondylitis? Ankylosing spondylitis (AS) primarily affects the spine, but may affect other parts of the body too. Signs and symptoms usually begin in adolescence or early adulthood and include back pain and stiffness. Back movement gradually becomes more limited over time as the vertebrae fuse together. Many affected people have mild back pain that comes and goes; others have severe, chronic pain. In very severe cases, the rib cage may become stiffened, making it difficult to breathe deeply. In some people, the condition involves other areas of the body, such as the shoulders, hips, knees, and/or the small joints of the hands and feet. It may affect various places where tendons and ligaments attach to the bones. Sometimes it can affect other organs including the eyes, and very rarely, the heart and lungs. Episodes of eye inflammation may cause eye pain and increased sensitivity to light (photophobia). Neurological complications of AS may include an inability to control urination and bowel movements (incontinence), and the absence of normal reflexes in the ankles due to pressure on the lower portion of the spinal cord (cauda equina). The Human Phenotype Ontology provides the following list of signs and symptoms for Ankylosing spondylitis. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Abnormal form of the vertebral bodies 90% Abnormality of the oral cavity 90% Abnormality of the sacroiliac joint 90% Arthralgia 90% Arthritis 90% Diarrhea 90% Enthesitis 90% Inflammatory abnormality of the eye 90% Joint swelling 90% Spinal rigidity 90% Abnormality of the thorax 50% Myalgia 50% Respiratory insufficiency 50% Abdominal pain 7.5% Abnormal tendon morphology 7.5% Abnormality of temperature regulation 7.5% Abnormality of the aortic valve 7.5% Abnormality of the pericardium 7.5% Abnormality of the pleura 7.5% Anorexia 7.5% Arrhythmia 7.5% Autoimmunity 7.5% Cartilage destruction 7.5% Hematuria 7.5% Hemiplegia/hemiparesis 7.5% Hyperkeratosis 7.5% Nephrolithiasis 7.5% Nephropathy 7.5% Nephrotic syndrome 7.5% Osteomyelitis 7.5% Proteinuria 7.5% Pulmonary fibrosis 7.5% Pustule 7.5% Recurrent fractures 7.5% Recurrent urinary tract infections 7.5% Renal insufficiency 7.5% Skin rash 7.5% Skin ulcer 7.5% Anterior uveitis - Aortic regurgitation - Back pain - Hip osteoarthritis - Inflammation of the large intestine - Kyphosis - Multifactorial inheritance - Psoriasis - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.