Williams Syndrome, 7q11.23 Deletion, FISH
Method Description Describes how the test is performed and provides a method-specific reference
The FISH test to diagnose Williams syndrome (WS) involves a commercial DNA probe for the elastin WS chromosome region (WSCR) that hybridizes to 7q11.23. The WSCR probe is used in conjunction with a control probe that maps to the terminal region of chromosome 7 (7q36). Ten of 10 metaphases with 2 ELN signals is considered normal, and 10 of 10 metaphases with 1 ELN signal is consistent with microdeletion of the WS critical region. (Ewart AK, Morris CA, Atkinson D, et al: Hemizygosity at the elastin locus in a developmental disorder, Williams syndrome. Nature Genet 1993:5:11-16; Nickerson E, Greenberg F, Keating MT, et al: Deletion of elastin gene at 7q11.23 occur in approximately 90% of patients with Williams syndrome. Am J Hum Genet 1995;56:1156-1161)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Samples processed Monday through Sunday. Results reported Monday through Friday, 8 a.m.-5 p.m. CST.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test