Atransferrinemia is a rare inherited disorder in which the body is unable to produce enough of the iron-binding protein transferrin. This protein is responsible for transporting iron throughout the body, and without it, iron levels can become dang...

Atresia of the urethra is a rare congenital disorder in which the urethra is abnormally closed or absent. This condition can occur in both males and females, but is more common in males. In males, the urethra is the tube that carries urine from th...

Atrial fibrillation (A-fib) is an irregular and often very rapid heart rhythm (a...

Atrial fibrillation (A-fib) is an irregular and often very rapid heart rhythm (arrhythmia) that can lead to blood clots in the heart. A-fib increases the risk of stroke, heart failure and other he...

Atrial fibrillation (AFib) facts Atrial fibrillation (also referred to as AFib) is the most common type of abnormal heart rhythm. AFib is caused by abnormal electrical discharges (signals) that generate chaotically throughout the upp...

Atrial septal aneurysm (ASA) is a congenital heart defect in which the wall between the two upper chambers of the heart (the atria) is abnormally thickened. This can cause blood to flow between the two chambers, leading to an increased risk of str...

Atrial septal defect, coronary sinus type (ASD-CS) is a rare congenital heart defect in which the atrial septum, the wall between the two upper chambers of the heart, is not completely formed. Instead, there is an opening between the two chambers ...

Atrial septal defect, ostium primum type is a congenital heart defect in which there is a hole in the wall (septum) between the two upper chambers (atria) of the heart. This type of defect is caused by a failure of the septum primum to form proper...

Atrial septal defect, ostium secundum type is a congenital heart defect in which there is a hole in the wall (septum) between the two upper chambers (atria) of the heart. This type of atrial septal defect is the most common type, accounting for ab...

Atrial septal defect, sinus venosus type is a type of congenital heart defect in which there is an abnormal opening between the upper chambers of the heart (the atria). This type of defect is usually located in the upper part of the atrial septum,...

Atrial septal defect-atrioventricular conduction defects syndrome (ASD-AVCD) is a rare genetic disorder characterized by a combination of two heart defects: an atrial septal defect (ASD) and an atrioventricular conduction defect (AVCD). An ASD is ...

Atrial septal defects (ASD) are a type of congenital heart defect in which there is a hole in the wall (septum) between the two upper chambers (atria) of the heart. This hole allows oxygen-rich blood from the left atrium to flow into the right atr...

Atrial standstill is a rare cardiac arrhythmia in which the atria of the heart stop beating. This condition can lead to a lack of blood flow to the rest of the body, resulting in dizziness, fainting, and even death. Treatment typically involves th...

Atrichia with papular lesions (APL) is a rare genetic disorder characterized by the absence of scalp hair (atrichia) and the presence of small, raised bumps (papules) on the skin. It is caused by mutations in the FOXL2 gene. Symptoms may include t...

Atrioventricular defect-blepharophimosis-radial and anal defect syndrome (AVBRAD) is a rare genetic disorder characterized by a combination of heart defects, blepharophimosis (a condition in which the eyelids are abnormally narrow), radial and ana...

Atrioventricular septal defect (AVSD) is a congenital heart defect in which there is an abnormal connection between the two upper chambers of the heart (the atria) and the two lower chambers of the heart (the ventricles). This defect can cause blo...

Atrophic lichen planus is a rare form of lichen planus, a chronic inflammatory skin condition. It is characterized by thin, atrophic (thinning) patches of skin that are usually lighter in color than the surrounding skin. The patches may be itchy o...