Faculty Bibliography

PURPOSE/OBJECTIVE:To assess the accuracy and reliability of comprehensive chromosome screening by next-generation sequencing (NGS) of human trophectoderm (TE) biopsy specimens. METHODS:The reliability and accuracy of diagnoses made by preimplantation genetic testing for aneuploidy (PGT-A) from TE biopsy were tested. Repeat biopsies of TE and inner cell mass (ICM) samples were obtained from thawed blastocysts previously tested by NGS. To test for the reliability of the NGS assay, biopsy samples were compared with the original PGT-A results. Prior NGS testing classified the TE samples as euploid, aneuploid, or aneuploid-mosaic. The resulting re-biopsied samples underwent SurePlex whole genome amplification followed by NGS via the MiSeq platform, with copy number value (CNV) determined using BlueFuse Multi Software. The primary outcome measure was reliability, defined as concordance between initial TE result and the repeat biopsies. Accuracy was determined by concordance between the TE and ICM samples, and compared between three chromosome types (disomic, aneuploid, and mosaic). RESULTS:Re-biopsies were performed on 32 embryos with prior PGT-A showing euploidy (10 embryos), aneuploidy of one or two chromosomes (4 embryos), or aneuploid-mosaic with one aneuploid chromosome and one mosaic chromosome (18 embryos). One hundred twenty-nine biopsy samples completed NGS (90 TE and 39 ICM biopsies) and 105 biopsy results were included in the analysis. TE biopsies provide a highly accurate test of the future fetus, with the ICM disomic concordance rate of 97.6%. Clinical concordance rates indicate that TE biopsies provide a reliable test when the result is euploid (99.5%) or aneuploid (97.3%), but less reliable when the result is mosaic (35.2%). CONCLUSION/CONCLUSIONS:TE biopsies predict euploidy or aneuploidy in the ICM with a high degree of accuracy. PGT-A with NGS of TE biopsies is shown to be highly reliable, with clinically relevant concordance rates for aneuploidy and euploidy over 95%. TE biopsies indicating mosaicism were less reliable (35.2%), presumably because mitotic non-disjunction events are not uniformly distributed throughout the blastocyst. However, classification of TE biopsy of PGT-A with NGS results as either aneuploid or euploid provides a highly reliable test.

The testis expresses the largest number of genes of any mammalian organ, a finding that has long puzzled molecular biologists. Our single-cell transcriptomic data of human and mouse spermatogenesis provide evidence that this widespread transcription maintains DNA sequence integrity in the male germline by correcting DNA damage through a mechanism we term transcriptional scanning. We find that genes expressed during spermatogenesis display lower mutation rates on the transcribed strand and have low diversity in the population. Moreover, this effect is fine-tuned by the level of gene expression during spermatogenesis. The unexpressed genes, which in our model do not benefit from transcriptional scanning, diverge faster over evolutionary timescales and are enriched for sensory and immune-defense functions. Collectively, we propose that transcriptional scanning shapes germline mutation signatures and modulates mutation rates in a gene-specific manner, maintaining DNA sequence integrity for the bulk of genes but allowing for faster evolution in a specific subset.

During mammalian development, gonadotropin-releasing-hormone-1 neurons (GnRH-1ns) migrate from the developing vomeronasal organ (VNO) into the brain asserting control of pubertal onset and fertility. Recent data suggest that correct development of the olfactory ensheathing cells (OEC) is imperative for normal GnRH-1 neuronal migration. However, the full ensemble of molecular pathways that regulate OEC development remains to be fully deciphered. Loss-of-function of the transcription factor Gli3 is known to disrupt olfactory development, however, if Gli3 plays a role in GnRH-1 neuronal development is unclear. By analyzing Gli3 extra-toe mutants (Gli3^Xt/Xt), we found that Gli3 loss-of-function compromises the onset of achaete-scute family bHLH transcription factor 1 (Ascl-1) positive vomeronasal progenitors and the formation of OEC in the nasal mucosa. Surprisingly, GnRH-1 neurogenesis was intact in Gli3^Xt/Xt mice but they displayed significant defects in GnRH-1 neuronal migration. In contrast, Ascl-1^null mutants showed reduced neurogenesis for both vomeronasal and GnRH-1ns but less severe defects in OEC development. These observations suggest that Gli3 is critical for OEC development in the nasal mucosa and subsequent GnRH-1 neuronal migration. However, the non-overlapping phenotypes between Ascl-1 and Gli3 mutants indicate that Ascl-1, while crucial for GnRH-1 neurogenesis, is not required for normal OEC development. Since Kallmann syndrome (KS) is characterized by abnormal GnRH-1ns migration, we examined whole exome sequencing data from KS subjects. We identified and validated a GLI3 loss-of-function variant in a KS individual. These findings provide new insights into GnRH-1 and OECs development and demonstrate that human GLI3 mutations contribute to KS etiology.Significance statement. The transcription factor Gli3 is necessary for correct development of the olfactory system. However, if Gli3 plays a role in controlling GnRH-1 neuronal development has not been addressed. We found that Gli3 loss-of-function compromises the onset of Ascl-1+ vomeronasal progenitors, formation of olfactory ensheathing cells in the nasal mucosa, and impairs GnRH-1 neuronal migration to the brain. By analyzing Ascl-1^null mutants we dissociated the neurogenic defects observed in Gli3 mutants from lack of olfactory ensheathing cells in the nasal mucosa, moreover, we discovered that Ascl-1 is necessary for GnRH-1 ontogeny. Analyzing human whole exome sequencing data, we identified a GLI3 loss-of-function variant in a KS individual. Our data suggest that GLI3 is a candidate gene contributing to KS etiology.

BACKGROUND/UNASSIGNED:The postpartum period can be a vulnerable time during which many women are prone to mood disturbances. Since telomere length (TL) is known to be associated with dysphoric moods, inflammation, and stress in many populations, this study's objective was to assess the relationships among TL, dysphoric moods, stress, and inflammation during the postpartum period. METHOD/UNASSIGNED:This cross-sectional pilot study is a secondary analysis of data collected in a larger parent study of anti-thyroid peroxidase (TPO) enzyme antibody positive versus negative women. The parent study followed selected mothers every month for 6 postpartum months. From this parent study, a random sample of preserved peripheral blood mononuclear cells from 97 participants collected at 2-4 months postpartum were measured for TL. Data were available on the production of interleukin-6 (IL-6), an inflammatory cytokine, in stimulated ex vivo cultures for 59 of these women. Dysphoric moods and stress were measured. Pearson correlations and linear regressions were performed, controlling for postpartum thyroiditis status and age. RESULTS/UNASSIGNED:There were no statistically significant relationships between TL and demographic factors, stress, depression, or TPO status. There were significant negative correlations between TL and anxiety and a trend for a relationship between TL and IL-6 levels. IL-6 levels were significantly, positively associated with negative moods. CONCLUSIONS/UNASSIGNED:Higher anxiety scores and inflammation were associated with shorter TL. Inflammation was related to anxiety and other dysphoric moods and was marginally associated with shorter TLs.

Uterus transplantation is an emerging technology adding to the arsenal of treatments for infertility; specifically the only available treatment for uterine factor infertility. Ethical investigations concerning risks to uteri donors and transplant recipients have been discussed in the literature. However, missing from the discourse is the potential of uterus transplantation in other groups of genetically XY women who experience uterine factor infertility. There have been philosophical inquiries concerning uterus transplantation in genetically XY women, which includes transgender women and women with complete androgen insufficiency syndrome. We discuss the potential medical steps necessary and associated risks for uterus transplantation in genetically XY women. Presently, the medical technology does not exist to make uterus transplantation a safe and effective option for genetically XY women, however this group should not be summarily excluded from participation in trials. Laboratory research is needed to better understand and reduce medical risk and widen the field to all women who face uterine factor infertility.