Congenital Hypotransferrinaemia

Congenital hypotransferrinaemia is an extremely rare blood disorder that creates a puzzling medical paradox: patients suffer from severe anemia while simultaneously accumulating dangerous amounts of iron in their organs.

Congenital atransferrinemia

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Table of contents

• What is Congenital Hypotransferrinaemia
• How Rare is This Disease
• Genetic Causes and Inheritance
• Signs and Symptoms
• How the Disease is Diagnosed
• Treatment Options
• Outlook for Patients

What is Congenital Hypotransferrinaemia

Congenital hypotransferrinaemia is a very rare blood disease caused by a deficiency of transferrin, which is a protein in the blood that carries iron throughout the body^[1]. This disorder is also known as congenital atransferrinemia, though hypotransferrinaemia is the more accurate term when some transferrin is still present.

The disease creates an unusual double problem. Without enough transferrin to deliver iron to developing red blood cells in the bone marrow, patients develop microcytic hypochromic anemia, meaning their red blood cells are smaller than normal and contain less hemoglobin than they should^[2]. At the same time, the body absorbs more iron from the intestines than it should, and this excess iron gets stored in organs like the liver, heart, and other tissues, causing iron overload^[2].

This condition can be life-threatening if not treated properly. The lack of transferrin prevents the body from delivering iron to immature red blood cells, which leads to a large increase in iron absorption in the intestines, resulting in the iron overload that defines this disease^[5].

How Rare is This Disease

Congenital hypotransferrinaemia is extremely rare. The disease affects less than 1 person in 1 million^[2]. According to medical literature, only 16 cases from 14 families have been reported worldwide^[1][2]. Because the condition is so uncommon, it can be overlooked or misdiagnosed, which means the true number of affected individuals might be slightly higher than reported.

Genetic Causes and Inheritance

Congenital hypotransferrinaemia is caused by mutations in the TF gene, which is located on the long arm of chromosome 3 at position 3q21^[1][2]. This gene provides instructions for making transferrin, the protein needed for proper iron transport to the liver, spleen, and bone marrow.

The disease follows an autosomal recessive inheritance pattern^[1][2]. This means a person must inherit two copies of the faulty gene, one from each parent, to develop the disease. Parents who each carry one copy of the mutated gene typically do not show symptoms themselves but have a 25% chance with each pregnancy of having a child with the condition. Both males and females have equal risk of inheriting the disorder.

When TF gene mutations occur, they result in defective levels of functional transferrin. Without enough transferrin, iron cannot be properly delivered to developing red blood cells in the bone marrow. This leads to reduced hemoglobin production, causing anemia, while excess iron accumulates in various organs throughout the body^[2].

Signs and Symptoms

The disease usually begins in infancy or early childhood, though one patient was not diagnosed until age 20^[2]. The symptoms and their severity can vary from person to person, depending on where and how much iron builds up in the body.

The most common early signs relate to anemia and include pallor (pale skin), fatigue, loss of appetite, irritability, rapid heartbeat, and a heart murmur that can be heard through a stethoscope^[2]. Children with the condition often experience growth delays and have frequent infections^[1][2].

Some patients may have an enlarged liver, a condition called hepatomegaly^[2]. As the disease progresses without treatment, the buildup of iron in various organs can cause serious damage. The liver, heart, joints, pancreas, kidneys, and thyroid gland can all be affected by iron accumulation^[5].

Over time, untreated iron overload can lead to severe complications including liver cirrhosis, heart failure, joint problems (arthropathy), and underactive thyroid (hypothyroidism)^[2]. In some cases, the spleen may become enlarged^[1]. Life-threatening complications can develop, such as pneumonia or congestive heart failure, where the heart cannot pump blood effectively, causing fluid to build up in the heart, lungs, and other parts of the body^[2].

The unusual characteristic of this disease is that patients have severe anemia that does not respond to iron supplements or standard treatments, while at the same time showing signs of too much iron in their body^[1].

How the Disease is Diagnosed

Diagnosis is based on laboratory testing that shows anemia along with very low levels of transferrin in the blood^[2]. Specifically, doctors look for a serum transferrin level of less than 35 mg/dL (the normal range is approximately 203-362 mg/dL)^[1][2].

Blood tests typically reveal microcytic hypochromic anemia with unusually high ferritin levels (indicating iron overload) but low serum iron levels^[1]. This combination of findings is highly unusual and should raise suspicion for congenital hypotransferrinaemia, especially when the anemia does not respond to repeated trials of iron supplements.

In some cases, an enlarged liver may be noticed during physical examination due to iron buildup^[2]. Molecular genetic testing can identify mutations in the TF gene, which confirms the diagnosis^[2]. Testing family members can also be helpful, as parents of affected children often have transferrin levels that are lower than normal, though not low enough to cause symptoms^[1].

Doctors must rule out other conditions that can cause low transferrin levels, such as GRACILE syndrome, kidney diseases that cause protein loss (nephrotic syndromes), and in adults, chronic alcoholism^[2].

For families who already have a child with the condition, prenatal diagnosis is possible for future pregnancies, but this requires prior identification of the specific mutations causing the disease in the family^[2].

Treatment Options

There is no cure for congenital hypotransferrinaemia, but there are treatments that can manage the condition effectively^[2]. The main treatment approach involves replacing the missing transferrin in the blood.

The standard treatment consists of regular infusions of fresh frozen plasma or purified apotransferrin (the iron-free form of transferrin)^[1][2]. These infusions are typically given monthly and help remove excess iron from the body while replenishing transferrin levels, which allows for proper formation of hemoglobin in red blood cells^[2].

In reported cases, patients have responded well to monthly fresh frozen plasma replacement, with improvements in their anemia^[1]. Some treatment protocols start with infusions every 8 weeks for the first 6 months, then adjust to every 4 weeks based on the patient’s response^[9].

Recent studies have shown that treatment with human apotransferrin can significantly improve hemoglobin levels and reduce iron overload. In one long-term study of patients treated for nearly 10 years, hemoglobin, hematocrit, and red blood cell counts increased to normal values and remained stable throughout the study period^[9].

Some patients may also benefit from additional iron supplementation given alongside plasma infusions, particularly during growth periods. One approach involves giving oral iron for 10 days around the time of each plasma transfusion to maximize the interaction between iron and transferrin^[10].

Treatment is lifelong, and patients require regular follow-up monitoring^[2]. Blood tests to measure hemoglobin, ferritin, serum iron, and transferrin levels are needed regularly to adjust treatment as needed. Imaging studies such as MRI may be used yearly to monitor iron levels in the liver and heart.

Outlook for Patients

With proper treatment, the outlook for patients with congenital hypotransferrinaemia is generally good^[2]. Regular plasma or apotransferrin infusions can effectively control the anemia and reduce iron overload, allowing patients to maintain normal hemoglobin levels and preventing organ damage.

However, because there have been so few reported cases, information about long-term complications remains limited^[2]. Patients who are not diagnosed or treated early may develop serious and potentially fatal complications from iron accumulation in vital organs. Death can occur from congestive heart failure or pneumonia if the disease is left untreated^[2].

The key to a good outcome is early diagnosis and consistent, lifelong treatment. With monthly transfusions and careful monitoring, patients can achieve and maintain stable blood counts and avoid the serious complications of iron overload. Genetic counseling is available for families affected by this condition to help them understand the inheritance pattern and risks for future children^[2].