Ansätze zur Untersuchung der genetischen Ursachen für den Erbfehler Stülpzitze beim Schwein (English shop)

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In mammals, the mammary complex is important for supplying the offspring with nutrients and for immunisation via the colostrum. The first anlagen of the teats are discernible early in foetal development. At the time of birth, the teat tips are already recognisable in newborns. From puberty onwards, the actual glandular tissue develops in female mammals. During pregnancy, a cycle of growth, functional differentiation and regression begins.

The functional capacity of the teat can be influenced by endogenous and exogenous factors. Disturbances in teat development can lead to defects of varying severity. The most important congenital teat defect in pigs is the inverted teat, which is found at frequencies of between 3 and 30 % in commercial pig breeds. This hereditary defect has considerable negative economic effects on pig production.

The mode of inheritance and the number of genes involved in this maldevelopment of the teat complex are still unknown. Various methods such as association analyses, linkage mapping and expression analyses are applied to detect the causes of the defect.

In the present study, a QTL analysis across eighteen chromosomes in pigs was carried out within the framework of a linkage mapping approach. The aim was to confirm the QTL detected in an experimental population in commercial families of the pig breeds German Landrace, German Large White and their crossbred animals. In addition, chromosomes 1, 2, 3, 4, 6 and 14 were mapped more finely with additional markers. In this way, regions on chromosomes 2, 3, 4, 6 and 11 could be confirmed. On chromosome 11 and chromosome 6, significant non-parametric likelihood (NPL) values were found in the analysis of all commercial families. Various positional and functional candidate genes were determined in these regions as well as in the comparative regions on the human chromosomes. An association analysis of the markers partly confirmed the QTL found. For further significantly associated markers, concordant positions with candidate genes were able to confirm their influence on the development of the inverted teat.