Smoking habits during pregnancy may cause genetic instability in the foetus

Dec 2 2004

The Spanish Pediatrics Association has recently awarded the Pediatrics laboratory at the University of Navarre for a research into tobacco and foetal genetic instability.

The study, by Marta Zalacaín, was carried out in conjunction with the Department of Gynacology and Obstetrics at the Hospital Virgen del Camino. “It involved analysing umbilical cords from many births which took place at both centres over three years and which have been distributed in four groups: non-smoking mothers, ex-smokers, those who stop smoking during pregnancy and those who continue to smoke. The aim was the look for any instability in the cord blood to see if there was any relationship with the smoking habits of the mother, either active or passive. In order to carry out this study, the collaboration by the Hospital Virgen del Camino has provided us with a very wide-ranging population of smoking mothers”, explains Marta Zalacaín. The research involved a questionnaire filled in by both the mother and father regarding their smoking habits, together with biochemical tests to measure cotinine in urine, the metabolite produced by nicotine in the body.

This work involves the micronuclei testing, the technology of which has been developed and applied successfully by Marta Zalacaín. According to Dr. Patiño, “When a genotoxic agent affects the cells, such as benzoapyrene in tobacco, genetic damage may be caused which interfere with cell division. As a product of this damage, a number of chromosomic fragments separate from the main nucleus and come together in a secondary nucleus known as a micronucleus. The research is aimed at seeing how the number of micronuclei vary amongst smoking and non-smoking mothers”.

The research undertaken at the Pediatrícs Laboratory aimed to test the efficacy of the micronuclei technique in detecting instability. “The development of this technology has not been an easy task, and involved working jointly with the CIFA Toxicology Department at the University of Navarre. Specifically, Marta Zalacaín had to carry out a great number of trials in order to test and validate the technique and see how the numbers of micronuclei changed while we increased the benzoapyrene in vitro. In a preliminary manner we found that the micronuclei numbers in vivo increased in samples of those mothers who actively smoked during gestation; nonetheless, these results have to be interpreted with precaution, given that the placentary barrier has to be taken into account and so it can never be known with exactitude how much benzoapyrene is being transmitted to the foetus”.

Apart from benzoapyrene, the research group has studied other genetic markers that tell us about tobacco habits, such as the status of mutation of the TP53 gene and the detoxifying enzymes of phase I and II drugs. “There are enzymes involved in detoxifying the organism which are more or less efficient in various individuals presenting genetic polymorphisms. We are currently looking at the genotype presented in these samples”.