MATERNAL CELL CONTAMINATION IN CHORIONIC VILLOUS SAMPLES FOR THE PRENATAL DIAGNOSIS OF THALASSAEMIA
Objective: To assess the frequency of maternal cell contamination (MCC) in chorionic villous samples (CVS) for prenatal diagnosis of thalassaemia.
Materials & Methods: This descriptive study was carried out at the Department of Hematology, Armed Forces Institute of Pathology (AFIP) Rawalpindi over a period of one and a half year from July 2008 to January 2010. Seventy CVS having β thalassaemia trait were selected by non-probability purposive sampling. The CVS was cleaned by microdissection under stereo zoom microscope at 16X magnification. DNA was extracted by phenol chloroform method after proteinase-K enzyme digestion. Parent’s β-thalassaemia mutations were tested by amplification refractory mutation system (ARMS). The presence of MCC in the CVS was tested by short tandem repeats (STR) analysis at D3S1358, D5S818, D8S1179 and D21S11 loci.
Results: None of the seventy samples showed any molecular evidence of MCC.
Conclusion: Meticulous microdissection of CVS can almost completely rule out errors in prenatal diagnosis of β thalassaemia due to MCC.
Key Words: Maternal contamination, Chorionic Villous Sample, Prenatal diagnosis, Short Tandem Repeats, Polymerase Chain Reaction.