Objective: Genetic carrier screening has the potential to identify couples at risk of having a child affected with an autosomal recessive or X-linked disorder. However, the current prevalence of carrier status for these conditions in developing countries is not well defined. This study assesses the prevalence of carrier status of selected genetic conditions utilizing an expanded, pan-ethnic genetic carrier screening panel (ECS) in a large population of Mexican patients.Methods: Retrospective chart review of all patients tested with a single ECS panel at an international infertility center from 2012 to 2018 were included, and the prevalence of positive carrier status in a Mexican population was evaluated.Results: Eight hundred five individuals were analyzed with ECS testing for 283 genetic conditions. Three hundred fifty-two carriers (43.7%) were identified with 503 pathogenic variants in 145 different genes. Seventeen of the 391 participating couples (4.34%) were identified as being at-risk couples. The most prevalent alleles found were associated with alpha thalassemia, cystic fibrosis, GJB2 nonsyndromic hearing loss, biotinidase deficiency, and familial Mediterranean fever.Conclusion: Based on the prevalence and severity of Mendelian disorders, we recommend that couples who wish to conceive regardless of their ethnicity background explore carrier screening and genetic counseling prior to reproductive medical treatment.

MATERIALS AND METHODS: This was a blinded prospective cohort study of 300 embryos with a previous clinical PGT-A result; embryos were chosen to include adequate numbers of specific initial diagnoses. Embryos were re-biopsied 4 times and individually tested by PGT-A in a blinded manner. Event concordance was determined according to partial confirmation rate (confirmed in some re-biopsies) and total confirmation rate (confirmed in all biopsies) in five categories: euploid, aneuploid, segmental aneuploid, whole chromosome mosaic, segmental mosaic.RESULTS: An initial TE biopsy result of euploidy or whole chromosome aneuploidy reconfirmed in >99% of re-biopsies. Approximately 97% of euploid or aneuploid embryos had initial biopsy results confirmed in all rebiopsies. In contrast, an initial result of whole chromosome mosaicism or segmental mosaicism confirmed in 15-18% of subsequent re-biopsies and segmental aneuploidy confirmed in 56.6% of re-biopsies. New secondary findings were identified in 7.2% of biopsies and 20.7% of embryos.CONCLUSIONS: An initial euploid or aneuploid result reconfirms in the rest of the embryo in almost all instances, affirming that meiotic errors -or lack thereof -are manifested in almost the entire embryo. The observed discordant rate of 2% is consistent with the mosaic rate in the general population. Mosaic abnormalities tend to be found in only limited areas of the embryo with the majority of the remaining embryo typically being normal. This may explain why these embryos have overall normal implantation and delivery rates. In contrast, segmental errors appear to be largely mitotic in nature. This is true even when they appear to impact all cells in the original biopsy. The high prevalence of mitotic errors explains why embryos with segmental abnormalities have ½ the implantation rates of euploids.IMPACT STATEMENT: Combining a reliable analytical platform and this new understanding of the biology of errors in human embryos should empower great confidence in PGT-A results.

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150 saliva samples were obtained and correlated with number and size of follicles.Weak correlation (r¼ 0.37) was seen in salivary oestradiol to total number of follicles A more promising correlation (r¼ 0.42) was observed when total number of follicles were adjusted to above 14mm.No correlation was detected in progesterone levels to follicular growth. No relationship was observed in salivary oestradiol or progesterone to endometrial thickness.CONCLUSIONS: These preliminary results show promising findings for correlation of saliva oestradiol to follicular growth to be explored in larger studies.The limitations of saliva sample include discoloured saliva samples, which is likely secondary to poor sampling technique or failure to collect according to protocol, all of which can be mitigated with improved training and education.The ease of saliva sampling allows a reduction in intervention and thereby provides a more "patient-friendly" approach to IVF.IMPACT STATEMENT: Current status quo of serial serum monitoring should be challenged as excessive.This alternative method of monitoring of cycle response in place of serum testing, especially during mid-cycle stimulation at day 5 or 6, is worth exploring.These preliminary results call for larger studies and has potential to revolutionise development of home testing kits, especially in the era of a pandemic, thereby reducing clinic footfall and patient safety.References