Bloom’s syndrome is a rare genetic disorder that can cause delays in growth and development, decreased immunity, and other disorders earlier in life.

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A child born with Bloom’s syndrome will need regular monitoring for different cancers that often do not occur until later in life. They have a much higher chance of developing cancer than children without this condition.

This article reviews Bloom’s syndrome symptoms, causes, affected populations, diagnosis, treatments, and frequently asked questions (FAQs).

Bloom’s syndrome can affect several areas of the body. The Bloom Syndrome Registry, which dates back to 1954, tracks and records observed clinical features of the condition.

Clinical features of Bloom’s syndrome can include:

  • small size and appearance
  • skin lesions in the shape of a butterfly on the nose and face, typically appearing after sun exposure when the child is 1 or 2 years old
  • issues with feeding, such as slow feeding and decreased appetite
  • an increased number of infections compared to peers
  • immunodeficiency

Children living with Bloom’s syndrome typically develop expected levels of intelligence on par with their peers.

Bloom’s syndrome increases a person’s risk of developing several types of cancer. At least 50% of people with this condition develop cancer in their lifetime. Their risk is 150–300 times higher than that of the general population.

In most cases, experts recommend regular screenings, often starting at an early age, to check for certain types of cancer, such as:

Bloom’s syndrome can also increase a person’s risk of developing other conditions, including:

Bloom’s syndrome is an inherited autosomal recessive disorder. This means a person will develop the condition only if they receive a mutated gene from each parent.

For a child to develop the condition, both parents must carry at least one copy of the mutated gene. Two parents who carry the mutation have a:

  • 25% likelihood of having an unaffected baby who does not carry the mutated gene
  • 50% likelihood of having an unaffected baby who carries the mutated gene
  • 25% likelihood of having a baby with Bloom’s syndrome

The odds do not increase or decrease with each pregnancy.

Genes and responsibilities

The BLM gene is responsible for the development of the condition. This gene makes BLM proteins, including a type called a RECQ helicase, which partially unwinds and rewinds a cell’s DNA during DNA replication and repair.

A defective RECQ helicase means the cells do not find and repair damaged DNA as quickly or replicate DNA as easily. This can result in either cell death or uncontrolled cell growth — cancer.

Geneticists often take an interest in Bloom’s syndrome because of the high volatility of chromosomes with a high mutation rate. The increased chance of mutations and changes to genes is likely responsible for both short stature and increased cancer risk in people with Bloom’s syndrome.

Bloom’s syndrome is an inherited, recessive trait. It affects males and females equally. If both parents carry the mutated gene, each pregnancy comes with a 25% chance that the child will develop the condition. To develop the condition, a child must receive one copy of the mutated gene from each parent.

Though anyone can develop Bloom’s syndrome, it is most common in people of Ashkenazi Jewish heritage from Poland or Ukraine. However, about 75% of all cases occur in people not in this demographic.

The number of reported cases of Bloom’s syndrome worldwide is about 283.

Diagnosis can often start with the appearance of characteristic clinical features, such as smaller stature or development delays in growth. Doctors may use genetic testing to confirm the diagnosis and rule out other conditions.

Genetic factors in diagnosis can include the identification of a BLM gene mutation known as a sister-chromatid exchange and a lack of mutations on the RMI1, RMI2, and TOP3A genes.

It is possible to diagnose the condition during prenatal testing.

There is currently no cure or permanent treatment for Bloom’s syndrome. Instead, treatments focus on addressing symptoms and monitoring the person for development of other conditions, such as cancer.

Treatment may include:

  • avoidance of unprotected sun exposure
  • monitoring for developmental delays
  • speech therapy, occupational therapy, or physical therapy as needed
  • use of assistive devices to help clear mucus from airways
  • use of growth hormones — but doctors often use these with caution due to cancer risks
  • a high calorie diet and assistance from a feeding specialist

Monitoring can include doctor visits to screen for cancer and other conditions. Parents or guardians should also learn about symptoms of blood sugar abnormalities, such as:

If another condition develops, such as cancer or diabetes, a person will need more treatment and monitoring. Additional precautions may be necessary during cancer treatment because it has the potential to damage DNA, leading to additional complications.

People may find genetic counseling helpful. Counselors can help people navigate the remainder of a pregnancy and connect them with resources.

The following sections provide answers to FAQs about Bloom’s syndrome.

Is there a cure for Bloom’s syndrome?

Currently, there is no cure for Bloom’s syndrome. Treatment typically involves addressing a person’s symptoms and monitoring their health for signs of cancer or other complications.

What is the life expectancy for Bloom’s syndrome?

The average life expectancy for people living with Bloom’s syndrome is 27 years. Most people with the condition die from cancer.

Is Bloom’s syndrome similar to any other conditions?

For several years, experts believed that Bloom’s syndrome was the only condition with a sister-chromatid exchange. However, more recently, researchers have found syndromes that affect the RMI1, RMI2, and TOP3A genes, which interact with the BLM proteins and can cause similar symptoms and an increased risk of cancer.

Experts refer to these as chromosomal instability syndromes. Examples include:

  • Cockayne syndrome
  • Nijmegen breakage syndrome
  • Russell-Silver syndrome
  • Werner syndrome
  • Rothmund-Thomson syndrome

Bloom’s syndrome is a rare disorder in which a genetic mutation causes delayed growth and development. People with this syndrome have an increased risk of developing cancer and other long-term conditions.

Symptoms often include smaller stature and delayed growth. The condition can also cause sensitivity to sunlight, insulin resistance, and immune system deficiencies. Life expectancy is generally shorter, and most people with the condition die from cancer.

Doctors can diagnose the condition during pregnancy or after birth. There is currently no cure, and treatment involves addressing symptoms and other conditions that develop as a result of Bloom’s syndrome.