Segregation von Pigmentzellanomalien bei Kreuzungen zwischen dem Münchener Miniaturschwein Troll und der Deutschen Landrasse

Abstract. Title of the paper: Segregation of melanocytic lesions in crosses among the Munich Miniature Swine Troll and German Landrace
Since 1986, a line of Munich Miniature Swine (MMS) Troll showing a high incidence of spontaneous benign and malignant cutaneous melanocytic lesions has been established at the University of Munich. In order to study me inheritance of cutaneous melanocytic lesions in the Munich Miniature Swine Troll, we established the F_1-, F_2-, B_IDL-, and B_ITroll-generations, starting with one melanoma-bearing MMS Troll boar and four non-affected sows of the German Landrace (DL) as founder animals. A total of 176 animals were available, 27 in the F_1-, 111 in the F_2-, 19 in the B_|DL-, and 14 in the B_ITroll-generation. Benign melanocytic lesions with two distinct forms of basal melanocytic hyperplasia or nests of hyperplastic melanocytes like in human junctional nevus were observed in 10 (41,7%) F_1-, 20 (18%) F_2-, 2 (10,5%) B_IDL-, and 7 (50%) B_ITroll-animals. Malignant melanomas were found in four (3,6%) F_2- and one (7,1%) B_ITroll-animals, but did not occur in the F_1- and B_IDL-generations. The observed segregation pattern suggests a different mode of inheritance for benign melanocytic lesions and melanomas, respectively. An influence of SLA haplotypes could not be observed. However, a significant influence of coat colour on the occurence of melanoma could be found in the F₂-generation. While around 65% of F₂-animals had the German Landrace dominant white colour, melanomas were only found in black and red animals. Benign lesions of the junctional nevus type, too, were only found in black animals. A possible explanation is the lack of melanocytes in the skin of dominant white pigs caused by a mutation of the KIT-gene, which leads to a failure of melanoblast migration and development