Hypotransferrinaemia

Hypotransferrinaemia is an extremely rare genetic blood disorder that causes a puzzling combination: severe anemia despite iron overload in the body. This life-threatening condition requires lifelong treatment with regular plasma infusions to survive.

Table of contents

• What is hypotransferrinaemia?
• Causes and inheritance
• Disease identification codes
• How rare is this condition?
• Signs and symptoms
• Diagnosis
• Complications and organ damage
• Treatment and management
• Outlook

What is hypotransferrinaemia?

Hypotransferrinaemia, also known as congenital hypotransferrinaemia or congenital atransferrinemia, is a very rare blood disorder characterized by a severe deficiency of transferrin, a protein that carries iron through the bloodstream^[1]. The disease causes a type of anemia called microcytic hypochromic anemia, which means the red blood cells are smaller than normal and contain less oxygen-carrying hemoglobin than they should^[1].

Congenital atransferrinemia, Congenital hypotransferrinemia

What makes this condition particularly unusual and dangerous is that despite having anemia, affected individuals also develop iron overload in their body tissues. This happens because without enough transferrin to transport iron properly, the body continues to absorb iron from food, but this iron cannot be delivered to the bone marrow where red blood cells are made. Instead, it accumulates in organs throughout the body, causing damage^[4].

Hypotransferrinaemia is a milder form compared to complete atransferrinemia, but both conditions are caused by mutations in the same gene and share similar characteristics^[4].

Causes and inheritance

Hypotransferrinaemia is caused by mutations in the TF gene located on chromosome 3 at position 3q21^[1]. This gene provides instructions for making transferrin, the blood protein that is essential for proper iron transport to the liver, spleen, and bone marrow^[9].

The condition is inherited in an autosomal recessive manner^[1]. This means that a person must inherit two copies of the faulty gene—one from each parent—to develop the disease. When two carrier parents (who each have one normal and one faulty copy of the gene) have a child together, there is a 25% chance with each pregnancy that the child will inherit both faulty genes and develop the condition. Both males and females are equally at risk^[4].

Recent research has identified several types of mutations that can cause this condition, including missense mutations, frameshift mutations, and regulatory variants that affect how the transferrin gene is read and expressed^[3].

Disease identification codes

10083911
C538259
E88.0

How rare is this condition?

Hypotransferrinaemia is an extremely rare disorder. As of recent reports, only 16 to 20 cases from 14 to 18 families have been documented in medical literature worldwide^[1][9]. The true prevalence is unknown, and the condition may be underdiagnosed or misdiagnosed in some cases^[4].

Signs and symptoms

The disease typically begins in infancy or early childhood, although in rare cases it may not be diagnosed until later. Most affected individuals are identified during their first few years of life^[1][9].

The primary symptoms relate to anemia and include pallor (pale skin), fatigue, anorexia (poor appetite), irritability, and weakness^[1]. Children with the condition often experience growth retardation, meaning they do not grow at the expected rate for their age^[1][9].

Affected individuals frequently develop recurrent infections due to a weakened immune system^[1][9]. An enlarged liver, known as hepatomegaly, is another common finding^[9].

The anemia is typically resistant to treatment with iron supplements or other standard treatments for iron deficiency, and many patients require blood transfusions^[1].

Diagnosis

Diagnosis is based on laboratory testing that reveals both anemia and abnormal iron metabolism. Blood tests show microcytic hypochromic anemia with unusually small red blood cells that are poorly filled with hemoglobin^[1].

The key diagnostic finding is a very low level of transferrin in the blood. A serum transferrin level of less than 35 mg/dL is consistent with the diagnosis^[9]. Normal transferrin levels typically range from 203 to 362 mg/dL^[1].

Additional laboratory findings include high serum ferritin levels (indicating iron overload) despite low serum iron levels^[1]. This paradoxical combination—anemia with iron overload—is highly characteristic of the condition.

The diagnosis can be confirmed through molecular genetic testing to identify mutations in the TF gene^[9]. In confirmed cases, testing of parents often shows transferrin levels that are lower than normal but higher than the affected child, consistent with carrier status^[1].

An important clue to diagnosis is that the anemia does not respond to repeated trials of oral iron supplements or other standard treatments for anemia^[1].

Complications and organ damage

Despite the presence of anemia, iron accumulates throughout the body because it cannot be properly transported to where it is needed. This iron overload can cause serious damage to multiple organs over time^[1].

The liver, heart, joints, pancreas, kidneys, and thyroid gland are all vulnerable to iron accumulation^[4]. Without proper treatment, iron overload can lead to liver cirrhosis, heart failure, and an enlarged spleen known as splenomegaly^[1][9].

Other complications that have been reported include arthropathy (joint disease) and hypothyroidism (underactive thyroid)^[9]. Some cases have also presented with developmental abnormalities such as hypospadias^[1].

Life-threatening complications can occur, including congestive heart failure and severe pneumonia^[9]. The condition can be fatal if left untreated^[9].

Treatment and management

There is no cure for hypotransferrinaemia. Treatment focuses on replacing the missing transferrin protein and managing iron overload^[9].

The primary treatment involves regular infusions of fresh frozen plasma or purified human apotransferrin (the iron-free form of transferrin) to replenish transferrin levels in the blood^[1][9]. This replacement therapy allows proper iron transport and enables the formation of hemoglobin.

Most patients receive monthly infusions, though the specific dose and frequency may be adjusted based on individual response^[1]. In clinical studies, patients have been treated with doses ranging from 75 to 150 mg/kg of apotransferrin every 4 to 8 weeks^[8].

Treatment with human apotransferrin has been shown to resolve anemia and reduce iron accumulation in organs. In one long-term study, patients treated for nearly 10 years showed rapid increases in hemoglobin levels to normal values, and ferritin levels (indicating iron stores) decreased to normal ranges over time^[8].

In some cases, phlebotomy (removal of blood) may be used to help remove excess iron from the body^[9].

Treatment is lifelong, and regular monitoring is essential to assess blood counts, iron levels, and organ function. This includes monitoring hemoglobin, transferrin levels, serum ferritin, and periodic evaluation of iron content in the liver and heart through imaging studies such as MRI^[8].

Outlook

With proper and timely treatment, the prognosis for patients with hypotransferrinaemia is generally good^[9]. Regular replacement therapy can normalize blood counts and prevent or reduce organ damage from iron overload.

However, because the condition is so rare and only a small number of patients have been followed long-term, the complete picture of long-term complications remains uncertain^[9]. Continued lifelong treatment and regular follow-up with healthcare providers are essential for the best outcomes.