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An Introduction

Klinefelter's Syndrome (KS) is a common congenital condition which is found in around 1 in 650 live male births and is the result of the presence of one or more additional sex chromosomes.

Chromosomes are genetic material and a person's sex is determined by X and Y chromosomes. Generally males have one X and one Y chromosome (XY), females have two X chromosomes (XX). 

Klinefelter's Syndrome is characterised by the pattern XXY.

KS is diagnosed by a blood test which identifies the karyotype i.e. the number, size and shape of the chromosomes.