What are some types of chromosomal disorders?

Chromosomal disorders are a result of an alteration in genetic material. These alterations can be grouped into three categories: error in number, deletions and point mutations.

Error in the number of chromosomes (too many or too few) includes the following disorders:

  • Down’s syndrome or trisomy 21: The individual has an extra chromosome 21.
  • Trisomy 18 or Edwards’s syndrome: The individual has an extra chromosome 18.
  • Trisomy 13 or Patau syndrome: The individual has an extra chromosome 13
  • Turner’s syndrome: Girls with Turner syndrome have one X chromosome and are missing all or part of the other X chromosome
  • Klinefelter syndrome: Boys with Klinefelter syndrome have two, or occasionally more, X chromosomes along with their Y chromosome.

Deletion of a genetic material on a specific chromosome such as:

  • Cri-du-chat (cat cry) syndrome: the individual is missing the short arm on chromosome 5
  • Prader-Willi syndrome: The individual has a deletion on chromosome 15

Point mutation or any insertion/deletion entirely inside one gene examples include:

  • Color blindness: Carried on the X chromosome and males with the gene have the disorder.
  • Cystic fibrosis: Carried on chromosome 7 as a recessive trait.
  • Tay–Sachs disease: Carried on chromosome 15.

There are many types of chromosomal disorders. The most common is Down syndrome, which is most often caused by an extra copy of chromosome 21. Fragile X is a disorder that has DNA abnormalities on the X chromosome. In boys, the abnormality is most often inherited from their mother. Kleinefelter's syndrome occurs when boys are born with an extra X chromosome and may cause complications at puberty. Children with Turner's syndrome are born missing part of or a whole X chromosome. These are only a few chromosomal disorders; there are rarer disorders as well.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.