Klinefelter syndrome

Klinefelter syndrome, 47, XXY, or XXY syndrome is a genetic disorder where people have an extra number of X chromosomes. People who have Klinefelter's Syndrome are often called "XXY Males", or "47, XXY Males".
Effects.
Males who have this condition are almost always infertile. This means that they cannot father babies.
In other organisms.
Any male mammal can have Klinefelter's Syndrome. The mouse is one example. 
Tortoiseshell or calico markings on male cats are an indicator of Klinefelter's syndrome. These cats are considered to be the model organism for Klinefelter syndrome, because the gene for a cat's orange/black coat markings is found on the X chromosome.