Heterotaxy syndrome

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at December 22, 2016
StartDiseasesHeterotaxy syndrome

Heterotaxy syndrome is a rare condition where the internal organs are found in the wrong places in the patient’s abdomen and chest. The heart is the organ that is most affected. It is more common in boys than girls, and some rare forms only affect boys.

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Definition & Facts

Heterotaxy comes from the Greek words “hetero,” which means different and “taxy” which means location. Most people are born with their organs in predictable places in their bodies. For example, the liver is mostly on the right side of the body, the spleen on the left, the heart just left of center.

In some cases, the organs are reversed in a condition called situs inversus. Most people with this condition are healthy. But children with heterodoxy syndrome are often very unwell because the organs are not only in the wrong place but so abnormal that they can’t function the way they should.

Heterotaxy syndrome is present at birth (that is, it's a congenital disorder) and affects about 4 in 1,000,000 people, though researchers believe the condition is under-reported. It is more common in Asia than in Europe or North America, and in the United States it is more common in Hispanic and African-American children than Caucasian children. Most children with heterotaxy syndrome don’t live past one year old if the disorder is left untreated.

Symptoms & Complaints

Babies who are born with heterotaxy syndrome are often cyanotic, or have a blue color under their fingernails or around their mouths because their blood is deprived of adequate oxygen.

They may be sluggish and have difficulty breathing or poor feeding. This is because of the multiple congenital heart defects that can affect the child. In one type of defect, the aorta of the heart and the pulmonary artery originate in the right ventricle of the heart instead of the left ventricles, or the arteries can be reversed.

In another defect, the septa, which are membranes that separate the four chambers of the heart, have holes in them. In some cases, the child does not have symptoms, and the defect or defects aren’t discovered until they are older.

Babies with heterotaxy syndrome are often born with no spleen or an unnaturally small spleen. Sometimes there are multiple small spleens, but they still do not function like a single, normal-sized spleen. Since the spleen is part of a person’s immune system, the baby is subject to constant infections, including septicemia, an infection of the blood.

Babies suffer abdominal pain, vomiting, and bloating because their intestines can be twisted in on themselves. Other sources of abdominal pain are a narrowing of the bile ducts. This is called biliary atresia. Narrowed bile ducts often lead to jaundice, which is a yellowing of the skin and the whites of the eyes (sclera).

The pancreas can be of an abnormal size or in an abnormal position and may not work properly. This has implications in the levels of necessary hormones and enzymes the pancreas produces, including insulin. The kidneys, skeleton, and nervous system can also be affected.

Causes

As of 2016, medical researchers do not know the exact cause of heterotaxy syndrome. They assume that it is caused by a great many mutations in the child’s genes, including those genes that determine where in the body organs should be placed. Sometimes, the child’s chromosomes have suffered deletions, rearrangements or duplications that result in heterotaxy syndrome.

Women who are exposed to toxins or who have diabetes during pregnancy seem to be at greater risk for having a baby with heterotaxy syndrome. The condition can appear for what seems to be no reason at all.

About 10 percent of children born with heterotaxy syndrome have a close relative who was born with a heart defect but not the other defects of heterotaxy syndrome. In rare cases where the condition is inherited, it can be caused by a defective gene from one parent, a defective gene from both parents, or a defect in the X chromosome.

Heterotaxy syndrome can be a stand-alone syndrome or can be accompanied by other genetic factors. These patients can have disorders such as primary ciliary dyskinesia, which causes them to be infertile and have chronic infections of their lungs, bronchial tubes, and other parts of the respiratory tract.

Diagnosis & Tests

Heterotaxy syndrome can be diagnosed before the baby is born through a fetal echocardiogram, which is a type of sonogram that measures the baby’s heart. If the baby is believed to have heterotaxy syndrome, the mother is monitored throughout her pregnancy. When the child is born, the baby is given at least one or sometimes all of these tests: 

Sometimes a baby needs to be fitted with a cardiac catheter to allow doctors to have a better view of the defects in their heart. This is usually done before surgery. Babies are given tests such as a liver-spleen scan to find defects in other organs of the body. 

Treatment & Therapy

Because heterotaxy syndrome has so many symptoms and effects, treatment differs from patient to patient. Some patients need cardiac surgery, including multiple open heart surgeries. Others will need defibrillators or artificial cardiac pacemakers to regulate their heart rhythm when they are older. Even if the patient does not need surgery, they will need to be monitored by a doctor who specializes in the heart problems of children.

Babies who are born without a spleen or a spleen that does not function well are often prescribed daily antibiotics to reduce their risk of infection. It's also important that they be given all necessary vaccinations. If the child does develop an infection, it needs to be treated very aggressively.

Children with biliary atresia often need liver transplants, and children with twisted intestines need surgery to correct the condition.

Prevention & Prophylaxis

There is no way to prevent heterotaxy syndrome. However, if the child does not have too many defects, if they are treated with surgery and other therapies, and if they are monitored by their physician, they can attain a high quality of life.