22q11.2 duplication syndrome

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
22q11.2 duplication syndrome
22q11 duplication syndrome.png
SpecialtyMedical genetics Edit this on Wikidata

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

Presentation[edit]

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[edit]

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[edit]

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[edit]

Treatment[edit]

References[edit]

  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[edit]

External links[edit]

Classification