Fast Prenatal Diagnosis With Automatic Interphase FISH Scanning
Ian Corless MD of Image Solutions (UK) Ltd., shows how automated interphase FISH scanning technique speeds up the slow and labour-intensive process of testing for chromosomal disorders.
In many countries, cytogenetic analysis of amniotic fluid for the diagnosis of chromosomal disorders is now a standard task and has reached an excellent level of analytical accuracy.
Traditional cytogenetic analysis requires the cultivation of foetal cells in the amniotic fluid for 1–3 weeks until analysis of metaphase chromosomes can be performed. However, patients at high risk of chromosomal abnormalities, as indicated by sonographic abnormalities, aberrant serum screening and being of advanced maternal age, would benefit from a more rapid analysis. This is especially true in countries with laws restricting the performance of abortions between 21 and 24 weeks of gestation.
One such technique is fluorescence in situ hybridisation (FISH) on uncultured amniocytes using chromosome-specific DNA probes. Between 80 and 95% of all chromosomal disorders, expected in the second trimester, can be discovered within 24 hours if DNA probes specific for chromosomes 21, 18, 13, X, and Y are used with FISH.