The most serious and frequent complication of Bloom syndrome is cancer. In the 281 persons followed by the Bloom Syndrome Registry, 145 persons (51.6%) have been diagnosed with a malignant neoplasm, and there have been 227 malignancies. The types of cancer and the anatomic sites at which they develop resemble the cancers that affect persons in the general population. The age of diagnosis for these cancers is earlier than for the same cancer in normal persons. And many persons with Bloom syndrome have been diagnosed with multiple cancers. The average life span is approximately 27 years. The most common cause of death in Bloom syndrome is from cancer. Other complications of the disorder include chronic obstructive lung disease and type 2 diabetes.