Bloom syndrome

Diagnosis and Testing

Why might a child be tested for Bloom syndrome?

Bloom syndrome may be suspected in children who were born very small with feeding difficulties shortly after birth; gastroesophagealreflux (GER) that causes recurrent infections of the ears and lung; and a butterfly-shaped patch of reddened skin across the nose and cheeks worsens after sun exposure.

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How are children tested for Bloom syndrome?

Is there newborn screening for Bloom syndrome?

Is there more than one genetic test for Bloom syndrome?

Who else in my family should I test for Bloom syndrome?

I already have one child with Bloom syndrome, what is the chance that I will have a second child with the condition?

If I have Bloom syndrome, can I have children?

If I have Bloom syndrome, what is the chance that I will have a child with the condition?

How are children tested for Bloom syndrome?

Children who have symptoms related to Bloom syndrome generally have a test to see if their DNA pieces are sharing too much information or a test to look for changes in the BLM gene. A blood sample is commonly needed for these tests.

Is there newborn screening for Bloom syndrome?

Bloom syndrome is not currently available on newborn screening. However, children with symptoms of Bloom syndrome should be evaluated by a doctor.

Is there more than one genetic test for Bloom syndrome?

Bloom syndrome is caused by gene changes, called mutations, in the BLM gene. Mutations in this gene can cause the replicated DNA copies (sister chromatids) during cell division to exchange too much genetic information. Testing can either look to see how many exchanges of information occur between the sister chromatids or to look for changes in the BLM gene.

Who else in my family should I test for Bloom syndrome?

Carriers of autosomal recessive conditions such as Bloom syndrome generally do not show symptoms of the condition and are unaware that they carry a change in the gene responsible. Family members of those with Bloom syndrome may wish to know whether they are carriers of a change in the BLM gene for family planning purposes. Family members who may want to know if they are carriers may include siblings, aunts, uncles, and cousins of people with Bloom syndrome or of people who are known carriers.

I already have one child with Bloom syndrome, what is the chance that I will have a second child with the condition?

Bloom syndrome is inherited in an autosomal recessive pattern, meaning that both parents of the child likely carry a change in the BLM gene. Each pregnancy between the parents of the affected child will have a 25% (1 in 4) chance of receiving two copies of the gene change causing that child to have Bloom syndrome, a 50% (1 in 2) of receiving one copy of the gene change causing that child to be a carrier, and 25% (1 in 4) chance of receiving two BLM gene copies with no changes.

If I have Bloom syndrome, can I have children?

Women with Bloom syndrome have been shown to have problems getting pregnant and often experience menopause at a young age. Men with Bloom syndrome do not produce sperm and as a result cannot have children.

If I have Bloom syndrome, what is the chance that I will have a child with the condition?

If you are a woman who has Bloom syndrome, your chance of having a child with the condition is dependent on whether your partner has a copy of the gene with a change that can cause the condition. Because approximately 1 in every 100 people of Ashkenazi Jewish background are carriers of Bloom syndrome, if a woman with Bloom syndrome has a child with a man of Ashkenazi Jewish background, there is a 1/200 chance their child will have the condition. If the man is not of Ashkenazi Jewish background, then their risk of having a child with the condition is low, but not zero.

Males who have Bloom syndrome are not able to have children because they do not produce sperm. This means a man with Bloom syndrome would not be able to have a child with the condition.

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