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Beckwith-Wiedemann Syndrome

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What is Beckwith-Wiedemann syndrome?

Beckwith-Wiedemann syndrome (BWS) is a genetic condition that affects many parts of the body and increases the risk of childhood cancer. One of the first indications a child may have BWS is fetal macrosomia, an overgrowth syndrome that makes the infant considerably larger at birth.

What is fetal macrosomia?

Newborns weighing more than 8 pounds and 13 ounces are considered larger than average. This condition is called fetal macrosomia and affects about 9% of all babies. The risks associated with fetal macrosomia increase greatly when the birth weight reaches more than 9 pounds and 15 ounces.

Babies with macrosomia are usually taller than their peers during childhood, but their growth begins to slow around 8 years old.

How does Beckwith-Wiedemann syndrome affect other parts of the body?

Sometimes in children with Beckwith-Wiedemann syndrome, specific body parts on one side of the body can grow larger than on the other, leading to an uneven or asymmetrical appearance. This growth pattern is known as hemihypertrophy and usually becomes less obvious over time as the child continues to grow.

The growth pattern alone does not usually increase health risks, but kids with BWS have an increased chance of developing childhood cancer. While the majority of children with BWS do not develop cancer, those who do can often be treated successfully.

Some children with BWS also have developmental delays such as speech problems that are usually related to hearing loss or having an enlarged tongue, which is called macroglossia.

What causes Beckwith-Wiedemann syndrome?

Beckwith-Wiedemann syndrome is a genetic condition. Genes are made up of deoxyribonucleic acid (DNA), which are made up of chromosomes. Genes form a kind of blueprint for the body and tell it how to form and function. There are two copies of each gene, one received from the egg and one from the sperm.

Typically, both genes are "turned on" or active. Some genes are "turned off" or inactive. The process of turning on and off genes is called genomic imprinting. Proper genetic imprinting is needed for growth an development.

The abnormalities involving genes on chromosome 11 that undergo genomic imprinting are what cause most cases of Beckwith-Wiedemann syndrome. About 80% of individuals with BWS have no family history of the syndrome. For these individuals, BWS is usually caused by an imprinting error that occurred sporadically. Approximately 5-10% of people have BWS due to a family history of the syndrome. For some people with BWS, the precise genetic cause is unknown.

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