Bloom syndrome is an inherited genetic disorder that causes short stature, skin rash and an increased risk of cancer.
Symptoms include skin sensitivity to sun exposure which can cause a butterfly-shaped patch of red skin across the nose and cheeks, as well as the back of the hands and forearms. Additionally, small clusters of enlarged blood vessels (telangiectases) often appear in the rash or in the eyes, along with patches of skin that are lighter or darker than the surrounding areas (hypopigmentation or hyperpigmentation). Other symptoms include a high-pitched voice as well as a long narrow face with a small lower jaw and prominent nose and ears. Affected individuals are also at an increased risk for cancer and tend to develop cancer much earlier in life than the general population, as well as developing more than one type of cancer. There is no treatment for this disorder other than supporting the symptoms that may arise and limiting contact with direct sunlight.
This condition is caused by pathogenic (disease-causing) variants in the BLM gene. Bloom syndrome exhibits autosomal recessive inheritance, which means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background. For example, individuals of Ashkenazi Jewish descent have a higher risk of carrying the disease, with a carrier frequency of 1 in 100. Carriers typically do not experience any symptoms of the disorder. Other names for this condition include congenital telangiectatic erythema.