what is chromosomal abnormality
Structural Abnormalities: Deletions (Cri du Chat) and Duplications (Pallister Killian) Structural chromosome abnormalities occur when there is a change in the structure or components of a chromosome. The total number of chromosomes is usually normal (46 total per cell). Structural chromosome abnormalities occur when part of a chromosome is missing, a part of a chromosome is extra, or a part has switched places with another part. Ultimately, this leads to having too much or too little genetic material. This is a cause of some birth defects. Each chromosome has many segments.