New Guidelines on FISH Genetic Testing

New guidelines issued by the American College of Medical Genetics (ACMG) and the American Society of Human Genetics recognizes fluorescence in situ hybridization (FISH)-based genetic testing as a medically appropriate option for patients undergoing amniocentesis for specific prenatal indications. The guidelines were published in the November/December 2000 issue of Genetics in Medicine.

Because of the high analytical accuracy of prenatal FISH for selected abnormalities, the new ACMG position states that FISH results may be reported to a doctor before the traditional chromosome analysis results are available. The College recommends that irreversible decisions to act on positive results should be "supported by two of the three possible pieces of information, i.e., FISH results, routine chromosome analysis, and clinical information.” The College recommends that traditional chromosome analysis be performed in addition to FISH so that the geneticist can determine why the abnormality occurred.

The original ACMG position highlighted unresolved analytical and clinical issues concerning the use of FISH technology in prenatal testing. The new guidelines show that many of these questions have now been answered. The current position is that "FISH technologies provide highly analytically accurate test systems…for those abnormalities detectable by these tests. The tests are standardizable and controllable.”

The guidelines were announced by Vysis, Inc. (Downers Grove, IL, USA), a developer and marketer of DNA-based clinical products, including FISH prenatal tests.



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