Definition for XXXX syndrome
From Biology Forums Dictionary
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.