Asthma is a common disease among children. As yet, there is no way to prevent asthma from occurring. Our aim is to understand the basic biology behind asthma better, with the aim of better preventive actions in the future. We are investigating an unsolved mystery. Children have asthma more often when the mother has the disease than when the father has it. If we can find the cause for this difference, it may lead us to a new mechanism behind the development of the disease. We will set up a series of specific hypotheses to explain the mystery. One hypothesis is that active maternal asthmatic disease and use of medication during pregnancy may influence the fetus unfavourably. Another is that maternal genetic variants, regardless of maternal disease, have an influence on the fetus over and above the genes that are transmitted to the child directly. A third possibility is that asthma is partly determined by genetic variability in the mitochondrial genes, which are transmitted from the mother to the child, whereas there is no transmission of mitochondrial genes from the father to the child. We are also interested in the possible effects of the variability in the length of the ends of the chromosomes (called telomeres), since there is a stronger maternal effect on the inheritance of telomere lengths. Also, we will look into the possibility that imprinted genes (inactivated if they come from one parent but not from the other) can predispose to asthma. We will also examine the effects of the child's environment after birth on the supposition that mothers and fathers can have unequal influence. For this, we can use untransmitted genes from the mothers and fathers as indicators of their relative efffects on the environment. All these hypotheses will be tested using data from the Norwegian Mother, Father, and Child Cohort Study (MoBa). The project has located a gene that gives a larger risk of asthma in the child when it is inherited from the mother than when it is inherited from the father. This can partly explain why asthma is more common when the mother has asthma than when the father has it.
