Chromosomal Abnormalities and Associated Disorders

Chromosomal abnormalities can lead to various trisomies and sex chromosome disorders. Trisomy 21 (Down

syndrome) is caused by an extra copy of chromosome 21 and is characterized by short stature,

epicanthal folds, a single palmar crease, and mild to moderate intellectual disability,

with higher risk in children of older mothers. Trisomy 18 (Edwards syndrome) and trisomy

13 (Patau syndrome) involve extra copies of chromosomes 18 and 13, respectively,

and are associated with severe developmental defects, organ malformations, and very low survival

rates. Sex chromosome aneuploidies include Turner syndrome (45,X), in which females

have short stature, webbed neck, absent menstruation, and sterility; Klinefelter syndrome (47,XXY),