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How long is the average lifespan of a person with XYY syndrome?

While most males have a 46,XY karyotype, males with XYY syndrome have a 47,XYY karyotype, meaning they possess an extra Y chromosome. In one nationwide study of diagnosed individuals with the condition, researchers found that the average lifespan of a person with XYY syndrome may be approximately 10 years less than that of the general male population.