RAPID ANEUPLOIDY SCREENING WITH FLUORESCENCE IN SITU HYBRIDIZATION TEST

Lab Section Category	Cytogenetics - PP FISH View write-up
Specimen Required	Amniotic fluid (3ml), chorionic villi (5mg), or fetal cord blood/neonate blood (1.0ml)
Indications	- Advanced maternal age (≥35 years at EDD) - Abnormal ultrasound findings - Positive maternal serum screening - Previous history of chromosome abnormality - Family history of Down syndrome - Parental anxiety
Method	FISH assay using LSI 13 and 21, and CEP X, Y, and 18 DNA probes labelled with fluorophores and analysed under fluorescence microscopy.
Test Results	Normal or Abnormal. If Abnormal, the abnormality is described in accordance to the International System for Human Cytogenomic Nomenclature (ISCN, 2020).
Reference Interval / Value	Individuals with a trisomy will show three copies of a particular DNA probe. Normal individuals will show two copies of each DNA probe. Females will show two copies of the X probe, males one copy of the X and Y probe each.
Turnaround Time	1 ~ 3 days
Day(s) Test Set up	Monday – Friday (office hours)
Remarks	This FISH test is usually requested in conjunction with conventional cytogenetic studies.

Change History Notes

Last Updated - 13 Jun 2025

RAPID ANEUPLOIDY SCREENING, WITH FLUORESCENCE IN SITU HYBRIDIZATION TEST