Sperm DNA fragmentation (SDF) index on day of transvaginal oocyte retrieval (TVOR) does not correlate with the incidence of segmental aneuploidy in blastocysts analyzed with targeted next generation sequencing (NGS)

Abstract

Sperm DNA fragmentation (SDF) is more common in infertile men and has been found to be associated with recurrent miscarriage in some studies1. SDF testing evaluates the extent of DNA strand breaks in a given specimen and has been proposed as an adjunct to routine semen analysis. Given that high levels of SDF indicate a greater number of DNA strand breaks in sperm, some have proposed that the association between high SDF and poor reproductive performance may reflect segmental aneuploidy that has not traditionally been detectable with preimplantation genetic screening (PGS)2. However, the increased resolution of NGS allows for improved identification of segmental imbalances and may be useful in addressing this question3. To evaluate the association between segmental aneuploidy (duplications and deletions) and sperm DNA fragmentation levels among trophectoderm biopsy samples evaluated with targeted NGS. This was a subgroup analysis of a prospective cohort study of females 35-40 years of age undergoing IVF with ICSI and PGS between December 2014 and May 2017. Routine clinical care was performed through TVOR, at which time a 0.5mL semen aliquot was isolated from the fresh specimen. SDF was evaluated with the Sperm Chromatin Structure Assay (SCSA®). Beginning in July 2016, PGS samples were evaluated using NGS and segmental aneuploid calls were included in clinical reports (in addition to whole chromosome aneuploidy). Reports indicated the % of fragmented sperm DNA (DFI). Patients were divided into 2 groups: (<15% and >15%) and incidence of segmental aneuploidy was compared between the groups in 2 ways: 1) any segmental aneuploidy (among all embryos, including those with an additional whole chromosome aneuploidy) and 2) segmental aneuploidy only (no other whole chromosome aneuploidy). A total of 169 cases were included in the analysis. DFI <15% was found in 123 specimens, while DFI >15% was found in 45 specimens. The median DFI for the entire study population was 11 (interquartile range: 8 to 15). Men in the 15% DFI group were older (40.6 vs. 38.0, p<0.01), but there was no difference in the age of the female partner (37.9 vs. 37.4, p = 0.71). There was no difference in the rate of conversion to blastocyst. The incidence of any segmental aneuploidy and only segmental aneuploidy was no different between the groups. The incidence of whole chromosome aneuploidy was also no different (Table 1). Specimens with elevated DNA Fragmentation used for ICSI do not result in an increased incidence of segmental aneuploidy in trophectoderm biopsy samples evaluated by NGS. These results suggest three possible rationales: 1) DNA damage in the male may be at least partially repaired by oocyte-derived mechanisms, 2) small deletions and duplications may be below the diagnostic threshold of current NGS technologies, or 3) SDF testing, which relies on average levels among pooled sperm, may be limited in its ability to prognosticate embryonic segmental aneuploidy.Tabled 1Table 1DFI ≤15% (N=126)DFI >15% (N=43)P ValueDFI %9 (7-12)20 (16-27)<0.001Female Age (years)37.4 ± 1.637.9 ± 1.90.71Male Age (Years)38 ± 5.940.6 ± 5.9<0.01Oocytes Retrieved13.2 ± 8.111.5 ± 9.00.18Blastulation Rate48.2% (525/1089)50.8% (159/313)0.45Whole Chromosome Aneuploidy (per embryo)34.7% (182/585)35.8% (57/159)0.86Any segmental aneuploidy (including in embryos with whole chromosome aneuploidy also)10.7% (56/525)11.9% (19/159)0.75Only segmental aneuploidy present (no other whole chromosome aneuploidy)5.3% (28/525)5% (8/159)0.99 Open table in a new tab