What Is Bloom Syndrome?

By Cristina Mutchler 

 Medically reviewed by Lyndsey Garbi, MD

Bloom syndrome, or Bloom's syndrome, is an extremely rare genetic disorder mainly characterized by short stature, extreme sun sensitivity, and increased cancer risk. Other potential complications affect multiple systems in the body.

It's caused by an inherited mutation in what's known as the BLM gene, which is particularly prevalent in people with Ashkenazi Jewish ancestry (Jews from northern and eastern Europe). There is currently no cure for Bloom syndrome, so treatment options are largely focused on preventing and managing the various symptoms and complications.1

Bloom syndrome is named after New York City dermatologist David Bloom. He discovered the condition in 1954 after observing patients with a sun-induced skin rash and shorter-than-average height.2 His research led to the creation of the Bloom Syndrome Registry, which records the few hundred individuals worldwide documented to have the disease.3

Bloom Syndrome Symptoms

Bloom syndrome comes with several signature symptoms, including some physical signs that are usually detected at birth or shortly after and others that may develop years later. The most common include the following:2

Abnormal Growth

One of the most noticeable physical features of Bloom syndrome is abnormal growth and small stature. People with Bloom syndrome tend to be much smaller in height and weight, and usually do not surpass 5 feet tall after reaching adulthood. A very thin or slim frame with little fat tissue under the skin is common.

Distinctive Features

Bloom syndrome is typically marked with distinguishing facial features such as a long, narrow face, a smaller lower jaw or chin, a pronounced nose, and prominent ears. A high-pitched voice may also be present.

Sun Sensitivity

Extreme sensitivity to the sun causes what's been described as a butterfly-shaped red and scaly rash across the nose, cheeks, or other parts of the body that receive frequent sun exposure, like the hands, arms, and neck.4

Other skin conditions such as hypopigmentation (lighter patches of skin), hyperpigmentation (darker patches of skin), and cheilitis (lip blistering) may also appear.

Feeding and Digestive Issues

Parents of newborns with Bloom syndrome have reported issues with feeding and a decreased appetite in their baby, which can continue into childhood. Experts think gastroesophageal reflux (GERD)—which is common in Bloom syndrome patients—may contribute to the feeding issues.5

Immunodeficiency

Bloom syndrome patients are usually immunocompromised, meaning the immune system doesn't work at full capacity. This makes them more susceptible to getting repeated infections.

Upper respiratory tract, ear, and lung infections are common, especially during infancy and childhood. Experts believe this is due to a deficiency in immunoglobulins (proteins responsible for fighting off different infections).2

Increased Cancer Risk

Bloom syndrome is linked to an increased risk of developing any type of cancer—particularly leukemia (cancer of the blood), lymphoma (cancer of the lymphatic system), skin, and gastrointestinal tract cancers. Bloom syndrome patients often develop more than one type of cancer, usually earlier in life than the general population.6

Increased Risk of Certain Medical Conditions

Insulin resistance, diabetes, chronic obstructive pulmonary disease (COPD), and developmental learning issues can occur more often in people with Bloom syndrome. In addition, Bloom syndrome also causes reduced fertility or fertility complications, and sometimes an early onset of menopause, marking the end of menstrual cycles.7

Causes

Bloom syndrome is an autosomal recessive inherited disorder, meaning that it is a condition inherited from both parents. Each parent contributes one copy of an abnormal gene to pass down Bloom syndrome.

Specifically, Bloom syndrome is caused by a mutation of what's known as the BLM gene, which has dozens of known variations and provides instructions for making a certain type of protein. Because of this mutation, the gene doesn't work correctly and is unstable, resulting in the various signs, symptoms, and complications of Bloom syndrome.8

Prevalence in the Ashkenazi Jewish Population

Certain ethnic groups are more likely to carry mutated genes for genetic disorders like Bloom syndrome. When both parents are from the same ancestral background, the chances of having a child with a certain genetic condition go up.

Although Bloom syndrome may occur in any ethnic group, it seems to appear more commonly among people with Ashkenazi (northern and eastern European) Jewish ancestry compared to non-Jewish populations due to a unique variation of the BLM gene common within this group.

For some context, of the roughly 300 people who have been officially diagnosed through the Bloom Syndrome Registry, approximately one-third are of Ashkenazi Jewish descent.4

Diagnosis

Bloom syndrome is typically first diagnosed based on symptoms observed during a medical exam, which can happen in the womb, at birth, or during infancy or childhood. The diagnosis may be confirmed through additional measures, such as:

• Blood testing: Also known as cytogenetic testing, a blood analysis can be done in a lab to check a person's chromosomes for features that align with a Bloom syndrome diagnosis.

• Genetic testing: Genetic testing (also known as DNA testing or molecular analysis) to clinically confirm an initial Bloom syndrome diagnosis looks for molecular abnormalities in the BLM gene inherited from both parents.9

• Prenatal testing: Ultrasound and other diagnostic tests used during pregnancy can help detect genetic abnormalities before birth and keep track of the baby's growth. For Bloom syndrome, this could include screening tests to measure weight gain, linear growth, and head circumference.10

Potential Bloom syndrome cases may also be identified before pregnancy if a couple is suspected of having the BLM mutation. Genetic counseling may be available to detect genetic issues and provide families with information about Bloom syndrome's risks and management.

Genetic counselors will collect information about your family and medical history and offer preconception counseling.11

Treatment

There is no cure for Bloom syndrome and no specific treatment for the underlying genetic mutation. Instead, treatment focuses on managing and preventing the symptoms to help improve quality of life, including:12

• Sun protection: Because Bloom syndrome patients are much more susceptible to skin cancer and often develop sun exposure–induced skin rashes, sun safety measures are vital. Experts recommend using a sunscreen with a sun protection factor (SPF) of at least 30, wearing hats and protective clothing, and avoiding being out in the sun during the day.4

• Infection treatment: People with recurring infections may be treated with supplemental immunoglobulins to help cut down on the severity and frequency of infections, and antibiotics may be prescribed for bacterial infections.13

• Insulin treatment: Bloom syndrome patients with insulin resistance have treatment options similar to type 2 diabetes treatments. This may include changes to diet, blood sugar monitoring, and insulin therapy, depending on the situation.

• Cancer treatment: Bloom syndrome patients should be screened regularly and monitored closely for signs of cancer—from skin cancer to lymphoma to everything in between. If cancer is detected, experts recommend using standard cancer treatments like chemotherapy and radiation with extreme caution since people with Bloom syndrome risk developing secondary cancers.14

• Nutritional support: Because Bloom syndrome patients tend to be small in stature, some doctors will recommend high-calorie formulas and foods to promote weight gain, especially in childhood.

• Cognitive assistance: If needed, physical, occupational, or speech therapies, services, and classes can be considered for Bloom syndrome patients who show developmental delays.

Prognosis

A Bloom syndrome diagnosis comes with an increased likelihood of developing cancer and a shortened life span, but that doesn't mean people with Bloom syndrome can't lead productive lives.

While research shows that the median overall life expectancy for Bloom syndrome is approximately 30 years, treatment options for symptoms and complications—along with early detection of cancer and other issues—could extend life spans by more than a decade.14

Early and frequent screenings may help produce a better prognosis. Recommendations include abdominal ultrasounds from birth throughout childhood. Also recommended from roughly adolescence onward are full-body MRIs (magnetic resonance imaging), thyroid function tests, blood sugar tests, colonoscopies and fecal immunochemical tests for colon cancer, and breast MRIs to detect breast cancer.15

Summary

Bloom syndrome is a rare genetic condition that can occur in any population but is more common in people of Ashkenazi Jewish ancestry. Symptoms include short stature, extreme sun sensitivity, and increased cancer risk. Treatment aims at reducing symptoms and health risks. There is currently no cure.

 Sources

National Center for Advancing Translational Sciences—Genetic and Rare Diseases Information Center. Bloom syndrome.

Cunniff C, Bassetti JA, Ellis NA. Bloom's syndrome: Clinical spectrum, molecular pathogenesis, and cancer predisposition. Mol Syndromol. 2017;8: 4-23. doi:10.1159/000452082

Weill Cornell Medicine. Bloom Syndrome Registry.

National Organization for Rare Disorders. Bloom syndrome.

Bloom Syndrome Association. Bloom syndrome and the digestive system.

Arora H, Chacon AH, Choudhary S, McLeod MP, Meshkov L, Nouri K, Izakovic J. Bloom syndrome. Int J Dermatol. 2014 Jul;53(7):798-802. doi:10.1111/ijd.12408

National Institutes of Health: National Cancer Institute. Bloom syndrome.

U.S. National Library of Medicine: Medline Plus. BLM gene.

Bloom Syndrome Association. Genetic testing.

Flanagan M, Cunniff CM. Bloom syndrome. GeneReviews.

Children's Healthcare of Atlanta. Bloom syndrome.

Cunniff C, et al. Health supervision for people with Bloom syndrome. Am J Med Genet A. 2018 Sep;176(9): 1872-1881. doi:10.1002/ajmg.a.40374

Schoenaker MHD et al. Immunodeficiency in Bloom's Syndrome. J Clin Immunol. 2018 Jan;38(1): 34-44. doi: 10.1007/s10875-017-0454-y.

Campbell MB et al. Bloom syndrome: research and data priorities for the development of precision medicine as identified by some affected families. Cold Spring Harb Mol Case Stud. v.4(2); 2018 Apr. doi: 10.1101/mcs.a002816

Cuniff C, Djavid AR, Carrubba S, et al. Health supervision for people with Bloom syndrome: Recommendations for screening and prevention. AM J Med Genet Part A. 2018;1-10.

By Cristina Mutchler
Cristina Mutchler is an award-winning journalist with more than a decade of experience in national media, specializing in health and wellness content.