What are the most common chromosomal disorders?
The major chromosomal aneuploidies are trisomy 13, trisomy 18, Turner Syndrome (45, X), Klinefelter syndrome (47, XXY), 47XYY, and 47XXX. Structural chromosomal abnormalities result from breakage and incorrect rejoining of chromosome segments.
What are the types of chromosomal abnormalities?
- Numerical Abnormalities: Overview of Trisomies and Monosomies. Down Syndrome. Trisomy 18 & 13. Turner Syndrome.
- Structural Abnormalities: Deletions (Cri du Chat) and Duplications (Pallister Killian) Translocations. Translocation Down Syndrome. Other Arrangements: Rings and Inversions.
- Mosaicism. Mosaic Down Syndrome.
How chromosomal abnormalities lead to genetic disorders?
An error in cell division called nondisjunction results in reproductive cells with an abnormal number of chromosomes. For example, a reproductive cell may accidentally gain or lose one copy of a chromosome. Changes in chromosome structure can also cause chromosomal disorders.