XXXXY Variation of Kleinfelter's Syndrome
49,XXXXY. This karyotype shows a variant
of Klinefelter's syndrome. Individuals with this syndrome are male, typically
with the karyotype 47,XXY. They exhibit a characteristic phenotype including
tall stature, infertility, gynecomastia and hypogonadism. Aneuploidy above
one extra chromosome is usually fatal but because of X-inactivation, which
"turns off" all but one X chromosome per cell, the effects of 3 extra chromosomes
are reduced.
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