Novel ploidy analysis in ectopic pregnancy

OBJECTIVE: To study whether a single-nucleotide polymorphism (SNP) array could be used to test tissue from ectopic pregnancy to distinguish whether ectopic pregnancies were aneuploid. DESIGN: Case series report. SETTING: Academic medical center. PATIENT(S): One hundred seventy-eight women who underwent surgery for ectopic pregnancy at Northwestern Memorial Hospital between 2015 and 2018 were eligible for participation; written consent was obtained from 33 patients. Eight subjects had sufficient DNA samples and were included in the analysis. Maternal and paternal DNA samples were self-collected by buccal swab. Archived paraffin tissue containing chorionic villi from each surgically removed ectopic specimen was analyzed using SNP microarray technology to determine chromosome number and evaluate for maternal cell contamination. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Prevalence of aneuploidy in ectopic pregnancy specimens as well as success of SNP array technology in formalin-fixed and paraffin-embedded specimens. RESULT(S): Subjects had a mean (±SD) age of 33.4 ± 5.4 years, body mass index of 23.4 ± 5.7 kg/m(2), 3.3 ± 1.8 prior pregnancies, and 1.5 ± 1.4 live births. Genetic testing revealed that all eight tested samples were euploid, 6 female and 2 male (two arr(1-22)x2, (X,Y)x1 and 6 arr(1-22, X)x2); maternal cell contamination was ruled out in all cases. CONCLUSION(S): This study showed proof of concept for the use of routinely stored formalin-fixed, paraffin-embedded tissue blocks with DNA extraction for SNP array to detect ploidy status of ectopic pregnancy. Although all tested samples were euploid, further research is needed to gain a definitive answer to this question and better understand the mechanism that leads to ectopic implantation.