Molecular lesions in Md-traDalleles of different populations. Schematic organization of exons in Md-tra. Exon 2b and/or exon 3 are included in male Md-tra transcripts and cause premature termination of translation due to the presence of in-frame translational termination signals. In females these exon sequences are skipped, giving rise to transcripts with an intact open reading frame. The positions of the reported Md-traD sequence variations are indicated by arrows and further details are described in the boxes below .