Are chromosomal abnormalities only confined to certain parts of your body?

No: The typical chromosomal(chm) defect shows up as abnormal chm in every cell of your body. Some cells do little (skin just sits there) while others do a lot ( form the heart, hands, brain). The need for detail in complex parts means the defect will have more effect. Rare chm defects produce a mosaic, where a fraction of the body has normal & others abnormal. Variable effect.