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Phelan-McDermid Syndrome, deletion 22q13 by FISH*

Test Code

F PMS*

Test Synonyms

N25/ARSA, del(22)(q13.3)

Methodology

Fluorescence in situ Hybridization (FISH)
*Performed by affiliate laboratory

Turnaround Time

7-9 days

Specimen Requirements

5mL peripheral blood in sodium heparin
3mL bone marrow in sodium heparin
Fixed cytogenetically prepared cells in sterile centrifuge tube with pellet visible in 3:1, Methanol:Acetic Acid

Specimen Stability
Blood and bone marrow = 4°C to 25°C, specimens are stable up to 72 hours
Fixed cell pellets are stable for years when stored at -28°C to 15°C
Storage & Handling

4°C to 25°C during transit, but specimens may be transported on refrigerated gel packs. Do not allow the gel pack to come in contact with the specimen. Do not freeze. Extreme temperatures should be avoided.

Causes for Rejection

Clotted specimen; Specimen exposed to extreme temperature; Anticoagulant toxic to cells; Insufficient number of cells

Reference Range

See report

It is recommended that all FISH studies be done in conjunction with routine cytogenetic studies. If the FISH result is normal, a chromosome analysis allows identification of more complex abnormalities.

Description

Some symptoms include neonatal hypotonia, absent/delayed speech, moderate/profound developmental delay as well as minor dysmorphic features, including dolicocephaly, periorbital fullness, long eyelashes, prominent/full brow, large fleshy hands, dysplastic toenail. Behavioral featues include decreased perception of pain, obsessive chewing or mouthing, autism or autistic-like affect.

References
  1. Moessner R et al. (2007). Contribution of SHANK3 mutations to autism spectrum disorders. Am J Hum Genet. 81:1289-1297.
  2. Phelan MC et al. (2005). Deletion 22q13 syndrome (Phelan-McDermid syndrome). Management of Genetic Syndromes. 2nd ed. SB Cassidy and JE Allanson. Wiley-Liss. 171-181.
  3. Wilson HL et al. (2003). Molecular characterisation of the 22q13 deletion syndrome supports the role of haploinsufficiency of SHANK3/PROSAP2 in the major neurological symptoms. J Med Genet. 40:575.