22q11.2 duplication syndrome

22q11.2 duplication syndrome is a rare genetic disorder caused by a duplication of a segment at the end of chromosome 22.

22q11.2 duplication syndrome
SpecialtyMedical genetics 

Presentation

The most frequent reported symptoms in patients with 22q11.2 duplication syndrome are mental retardation/learning disability (97% of patients), delayed psychomotor development (67% of patients), growth retardation (63% of patients) and muscular hypotonia (43% of patients).[1] However, these are common and relatively non-specific indications for cytogenetic analysis, and the extent to which the duplication of 22q11.2 causes these features is currently unknown. The duplication is frequently inherited from a normal parent, so it is clear that intellectual development can be normal.

Genetics

Duplications of 22q11 vary in size and thereby in gene content. They include the typical common 3-Mb microduplication, 1.5-Mb nested duplication, consistent with non-allelic homologous recombination (NAHR) using distinct low-copy repeats. These microduplications likely represent the predicted reciprocal rearrangements to the microdeletions characterized in the 22q11.2 region.[2] Smaller microduplications may occur within this highly dynamic with frequent rearrangements using alternative low-copy repeats as recombination substrates within and distal to the DiGeorge syndrome region.

Origin of duplication

The majority of 22q11 duplications are inherited often from a parent with a normal or near-normal phenotype. This is in sharp distinction to 22q11 deletion syndrome where about 90% of cases are caused by mutations that occur de novo.

Diagnosis

Treatment

gollark: Here is some more information:
gollark: Don't forget me!
gollark: It was such a great idea that I might have chosen to implement it, for instance.
gollark: Of course they would. Palaiaologos said *they* would.
gollark: Taking credit for everyone else's work is extremely efficient.

References

  1. Wentzel C, Fernström M, Ohrner Y, Annerén G, Thuresson AC (2008). "Clinical variability of the 22q11.2 duplication syndrome". Eur J Med Genet. 51 (6): 501–10. doi:10.1016/j.ejmg.2008.07.005. PMID 18707033.
  2. Ou Z, Berg JS, Yonath H, et al. (April 2008). "Microduplications of 22q11.2 are frequently inherited and are associated with variable phenotypes". Genet. Med. 10 (4): 267–77. doi:10.1097/GIM.0b013e31816b64c2. PMID 18414210.

Further reading

Classification
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.