These uncommon congenital disorders are characterized by defects in the heart, spleen and paired organs such as the lungs and kidneys.

[2] Right atrial isomerism is named for its discoverer, Swedish pathologist Biörn Ivemark.

[3] In right atrial isomerism, both atria of the heart are morphological right atria leading to associated abnormalities in the pulmonary venous system.

In addition, individuals with right atrial isomerism develop asplenia, a midline liver, malrotation of the small intestine and the presence of two morphologic right lungs.

[5] The Ivemark Syndrome Association, which is based in Dorset,[1] is one of the organisations dedicated to helping patients and funding research.