Preferential X-chromosome inactivation in women with idiopathic recurrent pregnancy loss

Objective: To determine whether preferential X-chromosome inactivation (P-X CI) relates to idiopathic recurrent pregnancy loss. Design: A retrospective study. Setting: Infertility clinics and laboratory. Patient(s): Women with idiopathic recurrent pregnancy loss (group I), women who had given birth to children but with no history of spontaneous abortio n (group II), and women without a history of pregnancy (group III) Intervention(s): DNA samples from the heterozygotes for the (CAG)n polymorp hism within the androgen receptor gene were modified with sodium bisulfite, PCR-amplified with primer pairs for methylated androgen receptor alleles ( M-PCR) and unmethylated alleles (U-PCR), and subjected to electrophoresis. Main Outcome Measure(s): Band peak patterns and peak area sizes. Result(s): In group I, 7 (16.7%) of 42 heterozygotes exhibited P-XCI; four possessed single-peak patterns in the M-PCR and U-PCR products, and three h ad two-peak patterns in which the peak sizes differed considerably. In grou p II, 2 (5.6%) of 36 heterozygotes exhibited P-XCI as determined by the two -peak patterns. In group III, none of the 47 heterozygotes exhibited P-XCI. Conclusion(s): The incidence of P-XCI was statistically higher in group I t han in the other groups. As P-XCI characterized by single-peak patterns was observed only in group I, such patterns, which may result from undiscovere d cytogenetic or molecular abnormalities of the X-chromosome, likely correl ate with pregnancy loss. (C) 2001 by American Society for Reproductive Medi cine.