[Identification of a very short YCAII allele in the northern Polish population].

The YCAII system is one of the Y-chromosomal STR markers with dinucleotide repetitive units and due to the duplication on the chromosome, its amplification provides two polymorphic products. Due to the high polymorphism, YCAII was included in the Y-STR Haplotype Reference Database (http://www.ystr.org) and significantly increased discrimination power of the collected haplotypes. During studies on the Y-STR polymorphism in the Polish population, a very short YCAII allele with relatively low stutter was identified. Sequencing revealed the presence of 11 dinucleotide repetitive units characteristic of this system. Among 3998 extended haplotypes collected in the database, this allele was found only in the population of south-western Germany. Similarities between the haplotypes possessing the YCAII*11 allele suggest their common origin.