DNA extraction from chorionic villi for prenatal diagnosis of foetal haemoglobin genotype.
Extraction of DNA from the chorionic villi is the first major step in the molecular determination of foetal haemoglobin genotype. There are few reports on DNA extraction from the chorionic villi. A desired method should be simple to conduct, reliable and cost effective. The aim of the study was to demonstrate that boiling-based protocol for DNA extraction can be used for the prenatal determination of foetal haemoglobin genotype in a low resource setting. Chorionic villi obtained from 10 women in transabdominal procedures were treated with trypsin. Prepared solution 1, (0.5gm NaOH , 250mls distilled H20 at pH 8.0) was added to the sample and boiled. Finally prepared solution 2 (6.05gm TrisHCl and 250 mls of distilled H20 at pH 7.5) was added. Extracted DNA was amplified using PCR , run on gel electrophoresis and gel imager for determination of foetal genotype. DNA was successfully extracted and foetal genotype determined in all cases. The mean wet weight of sample was 25 mg with twice aspirations in 50% of women. Foetal genotypes were AA in five, AS in four and SS in one. No case of repeat extraction on account of inability to obtain a genotype was reported. Boiling-based method is a rapid and reliable way to extract DNA from the chorionic villi.