X Polysomies, in Females
Trisomy X; Triple X; Tetrasomy X; Pentasomy X; 47, XXX; 48, XXXX; 49, XXXXX
Definition and Characteristics
47,XXX is characterized by an extra X chromosome that is of maternal origin in the majority of cases . Females with X trisomy cannot be identified at any age by specific physical or behavioral features and might not come to medical attention, therefore, in the majority of cases. Trisomy X results from non-disjunction in meiosis I or II and rarely from post-zygotic non-disjunction. The mechanism underlying tetrasomy X and pentasomy seems to be successive non-disjunction in maternal meiosis I and II .
Molecular and Systemic Pathophysiology
47, XXX: While