The Organs Are Placed in Other Locations

There are also people, however, whose organs are assembled exactly the other way around. One in about 8,500 people is affected by heterotaxy, as this condition is called. Taking a major city such as Frankfurt a. M. as an example, this would statistically apply to over 80 people. This disease is referred to as situs inversus, which means that the heart and all the other organs are asymmetrically mirrored from their normal positions. In certain individuals, the order of the inner organs is in fact completely disarranged. Patients with so-called situs inversus or heterotaxy, respectively, can be recognized by the fact that each organ seems to pick its own place in the body regardless of the other organs. The distribution of the heart, liver, spleen, as well as the position of the intestinal coils, are random. And this is what usually causes complications.

Diagnosis is already Established during Pregnancy

Heterotaxy is frequently diagnosed at a very early stage. It is established during pregnancy, or, if this is not the case, shortly after birth. Newborns in which the inner organs are randomly assembled often have a bluish skin, do not drink well and have breathing difficulties. These symptoms could be caused by congenital heart disease which affects almost every child with heterotaxy.

Gene Mutations Might Be Responsible

Although congenital heart disease occurs relatively frequently, the causes are still not entirely clear even today. It is certain, however, that a considerable proportion has a genetic cause. Accordingly, mutations in certain genes can be the cause of an abnormal heart development. This mostly applies to genes that are heart-specific. In certain cases, however, it does not necessarily have to be a gene from right within the heart that guides the heart’s development.

The Body has to be Able to Know the Difference between Right and Left

At a very early stage during development, the body axes are defined. This determines the outer and inner form of our body. In this context, the normal development of the left-right axis and, accordingly, of an inner asymmetry, is important particularly for the development and placement of the heart. If the body does not know where its left and right side will be, this will lead to complications in the organs’ placement that are not visible from the outside. In particular, this can result in heart malformations, that is, congenital heart disease.

Donated Data from the Register Support our Research

At the University of Ulm, we are investigating the development of such heart defects that are caused by an irregular determination of left and right in the body. By means of the DNA of heterotaxy patients that is stored in the biorepository of the National Register for Congenital Heart Defects, we are looking for mutations in a gene that is essential for the functioning of adult hearts. Preliminary tests have revealed that this gene plays quite a significant role in the determination of the organ asymmetry and, above all, in the development of the heart.