Bloom syndrome (BSyn) is a rare chromosomal breakage syndrome characterized by a marked genetic instability associated with pre- and postnatal growth retardation, facial sun-sensitive telangiectatic erythema, increased susceptibility to infections, and predisposition to cancer.
Individuals with BSyn show proportionate growth retardation of prenatal onset and have a short stature (average adult height of 150 cm). Respiratory and gastrointestinal tract infections of variable severity (e.g. otitis, pneumonia) occur frequently throughout childhood and are associated with variable immunodeficiency. Gastroesophageal reflux with tracheal aspiration, common during infancy, may contribute to respiratory infections. Telangiectatic erythema appears during the first 1-2 years of life on the face (in particular the cheek) and dorsum of the hands. One major feature of Bsyn is a greatly increased predisposition to cancers in a distribution corresponding to the general population but occurring at a much younger age. The most common malignancies are leukemias and lymphoma during childhood and adolescence, and various types of adenocarcinomas during adulthood (e.g. colon, esophagus, breast). Rare tumors such as Wilms tumor and osteosarcoma may occur during childhood. Several individuals have had more than one primary tumor. Other usual features are poor feeding during infancy, and an exceptionally sparse subcutaneous adipose tissue giving a wasted appearance. Dolichocephaly, narrow face, prominent nose and ears, and malar and mandibular hypoplasia can be observed. Additional features include blistering and bleeding from the lips, patchy areas of hyper- and hypopigmentation, male infertility, and premature menopause. Decreased attention span and reduced memory function result in lack of interest in learning, but intellectual disability is not present. Ocular anomalies (e.g. conjunctivitis, bilateral optic nerve hypoplasia) have been reported.
Overall prevalence is unknown, but in the Ashkenazi Jewish population it is estimated at approximately 1/ 48,000 births.