Fig. 1

Schematic view on euchromatic part of the long arm of the human Y chromosome with focus on Yq11.22 including the “classical” AZFb deletion interval also known as (P5/proximal P1.2 deletion) encompassing 6.23 Mb genomic Y DNA and overlapping with AZFc for 2.3 Mb in Yq11.23 (for more details see ref [12]). a Repetitive sequence blocks with high sequence homology (< 99.7%) and designated as “amplicons” are displayed with a specific colour code as follows: yel(low) 1, 2, 3; b(lue) 1, 2, 3, 5, 6, t(urquoise) 1, 2; g(reen) 1; r(ed) 1, 2; gr(ey) 1. They are organized in 5 palindromes (P1–P5) as indicated. The X homologous single copy regions in AZFb are marked with: u(nique) 1. u(nique) 2,3 are Y specific single copy spacer regions of amplicons. DYZ19 is a tandem repetitive sequence block composed with 125 nts long sequence units along 400 kb (i.e. 3200 repeats). STS markers used in the clinic for diagnostic analyses of AZFb deletions are given with their positions above the amplicon structure. Those coloured in orange (+STS present; −STS absent) are used in ref. [16] to curtail the putative AZFb break sites of a “classical” AZFb deletion according to ref. [12] and including deletion of all Y genes listed in b. STS markers coloured in grey are used in ref. [17]. Absence of neighboured sY127 and sY134 in u1 is used in ref. [17] to indicate presence of complete AZFb deletions. b Schematic map of positions and polarities of the Y genes in AZFb encoding proteins according to ref. [11, 12]. RBMY1 is composed of 6 gene copies located in two distinct Y regions from proximal to distal: RBMY1B, RBMY1A1, RBMY1D, RBMY1E, in u1 and RBMY1F, RBMY1J, in t1 and t2, respectively. All AZFb Y genes are expressed in male germ cells during spermatogenesis as described in the main text