Tags: Disease.
XXXX syndrome (also called tetrasomy X quadruple X or 48 XXXX) is a rare chromosomal disorder caused by the presence of four X chromosomes instead of two X chromosomes. This condition occurs only in females as there are no Y chromosomes present. Tetrasomy X was first described in 1961 and since then approximately 100 cases have been reported worldwide. Approximately 60 females have been described in medical literature with this condition.[citation needed]
