Bloom syndrome is a rare genetic disorder characterized by short stature; increased skin sensitivity to ultraviolet rays from the sun (photosensitivity); multiple small dilated blood vessels (telangiectasia) over the nose and cheeks resembling a butterfly in shape; mild immune deficiency with increased susceptibility to infections; and most importantly, a markedly increased susceptibility to many types of cancer, especially leukemia, lymphoma and gastrointestinal tract tumors.