Abstract: Objective To explore the identification method of full sibling between two males with microdeletion and mutation of Y chromosome. Methods DNA were extracted from two samples. The type testing of Y-STR and autosomal STR were performed. Full sibling between two individuals was calculated by IBS, ITO and discriminant functions methods. Results There were 2 loci mutations existed in 33 Y-STR loci and one of the two samples had 19 loci deletions. The IBS of two samples was 53 and greater than the threshold which was 42; FSI was 1.36×1016 and far greater than 19. The discriminant function of full sibling-unrelated individual DFS2 was greater than DR2, which meant the two individuals tend to be full sibling. Conclusion The methods of IBS, ITO and discriminant functions of full sibling-unrelated individual can be used comprehensively to provide more reliable expert opinion in microdeletion and mutation of Y chromosome in full sibling identification.

Key words: forensic genetics, Y chromosome, sibling relations, chromosome deletion, mutation