ICD-11 definition : Klinefelter syndrome defines a group of chromosomal disorders in which there is at
least one extra X chromosome compared with the normal 46,XY male karyotype. The effects
on physical features and on physical and cognitive development increase with the number
of extra X's, and each extra X is associated with an intelligence quotient (IQ) decrease
of approximately 15-16 points, with language most affected, particularly expressive
language skills.;
ICD-11 synonym : Klinefelter syndrome, unspecified; Klinefelter syndrome in males;
Klinefelter syndrome defines a group of chromosomal disorders in which there is at
least one extra X chromosome compared with the normal 46,XY male karyotype. The effects
on physical features and on physical and cognitive development increase with the number
of extra X's, and each extra X is associated with an intelligence quotient (IQ) decrease
of approximately 15-16 points, with language most affected, particularly expressive
language skills.