Fig. 1

Schematic representation of the AZFc region of Chromosome Y, showing amplicon arrangements. STSs, and the rearrangements of AZFc deletions and microdeletions. a Reference sequence of the AZFc region with STSs used for detecting deletions in AZFc. STSs are shown above the AZFc sequence line. Arrows represent different amplicons and their orientation. a Derived from Kuroda-Kawaguchi [2]. Red copies numbered r1 to r4 show the position of the four DAZ copies. a′ The amplicon structure of the AZFc region with complete b2/b4 deletion is shown. A b2/b4 DAZ deletion was defined as the presence of sY1201, sY1161 and sY1125, and loss of sY1191, sY1291, sY1054 and sY1206. b, b′ A b1/b3 deletion was defined as loss of sY1161, sY1191 and sY1291 and the presence of other STSs. Three different gr/gr deletions of the AZFc region were observed in c1, c2, c3 and c1′, c2′, c3′. These deletions were defined as loss of sY1291 and the presence of the other STSs: (1) c1 (c1′) shows a DAZ3/DAZ4 deletion, and (2) c2 (c2′), (3) c3 (c3′) show a DAZ1/DAZ2 deletion. Several b2/b3 partial deletions are shown in d1, d2, d3, d4 and d1′, d2′, d3′, d4′. A b2/b3 deletion was defined as loss of sY1191 and the presence of the other STSs. Two mechanisms for these deletions have been reported: (1) gr/gr inversion (g1, r1, r2 recombination with r3, r4 and g3) followed by b2/b3 deletion via homologous recombination (d1 and d2) and (2) b2/b3 inversion followed by rg/rg deletion via homologous recombination (d3 and d4)