[MIM 208 530]

(right atrial isomerism)

Very rare. Sporadic or autosomal recessive transmission of a  mutation of the GDF1 (19p13.11) or the ZIC3 gene (Xq26.2). Association of variable severity of heart defect, asplenia and heterotaxy.

Two forms:

• right atrial isomerism (most common): a double-outlet right atrioventricular canal or ventricle, abnormal pulmonary venous return, and transposition or malposition of the large vessels. Both lungs are trilobulated, the liver is medial and there is asplenia. A situs inversus of other organs may be associated
• left atrial isomerism: presence of two superior vanae cavae and abnormal pulmonary venous return; absence of the intrahepatic portion of the IVC; polysplenia; both lungs are bilobulated

The aorta and the lower vena cava are located on the same side of the vertebral axis.

Often: renal dysplasia, pancreatic cysts and portal fibrosis with ductular proliferation.

Forms due to a mutation in the ZIC3 gene are associated with midline abnormalities: hypertelorism, anophthalmia, arhinencephaly, holoprosencephaly, hydrocephalus, meningocele, cleft palate, sacral or anal abnormalities

See also heterotaxy.

Anesthetic implications: 

echocardiography; check renal and hepatic functions. Prophylactic antibiotics as the risk for infection is increased.

References : 

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Updated: December 2020