>>12489679"An extra X chromosome in a male, producing XXY, occurs
approximately once in every 500 to 1,000 live male births.
People with this disorder, called Klinefelter syndrome, have
male sex organs, but the testes are abnormally small and the
man is sterile. Even though the extra X is inactivated, some
breast enlargement and other female body characteristics are
common. Affected individuals may have subnormal intelligence. About 1 of every 1,000 males is born with an extra
Y chromosome (XYY). These males undergo normal sexual
development and do not exhibit any well-defined syndrome,
but tend to be taller than average.
Females with trisomy X (XXX), which occurs once in
approximately 1,000 live female births, are healthy and have
no unusual physical features other than being slightly taller
than average. Triple-X females are at risk for learning disabilities
but are fertile. "
>extra Y chromosome : become taller>extra X chromosome: become retardedSource: Campbells Biology 8th Edition
