Heterosome X premutation structural changes associated with fertility of Romanov sheep

Cytomolecular analysis of spontaneous and in vitro induced heterosome X permutation structural changes in Romanov sheep revealed a high level of Xq11, Xq22, Xq31 and Xq32/33 region instability in infertile ewes. The highest frequency of structural defects was found in OAR Xq22 region comprising unstable trinucleotide CGG repetitions of FRM1 gene regulatory sequence, identified by in situ PCR method. The results obtained suggest that chromosome X structural instability in sheep may be the cause of inappropriate expression of genes determining reproductive traits and increased rate of aneuploid germ cells related to prenatal and perinatal mortality.