P-559 Preimplantation genetic testing for monogenic diseases : are there any predictive factors for live birth rate ?
Authors: Mayeur A , Vaucoret V , Magnan F , Steffann J , Benguigui J , Duperier C , Monnot S , Benachi A , Frydman N , Grynberg M , Sonigo C 
Published: June 2022

Abstract

Study question
Does the chance of having a healthy baby after PGT-M differ according to the known risk of inherited genetic pathology: autosomal recessive or dominant mode?

Summary answer
Live birth after PGT-M is not impacted by the inherited mode of genetic transmission. Age and ovarian reserve markers are predictive factors.

What is known already
The effectiveness of PGT-M, is conditioned by the number of healthy embryos obtained and therefore by a sufficient number of collected oocytes. Depending on the mode of genetic transmission, the probability of having a healthy embryo after cells biopsy varies from 25% (recessive transmission mode) to 50% (dominant transmission mode). It was commonly assumed that CLBR is directly impacted by female age but there are no published study related how the inherited transmission mode of the disease requiring PGT-M affects the chance to have a healthy baby.

Study design, size, duration
The present study is a monocentric retrospective observational study carried out from January 2006 through January 2020 in a French PGT center. Four hundred and seventy-four couples undergoing molecular PGT-M were classified into two groups based on risk of disease transmission (25% risk, P25 group or 50% risk, P50 group).

Participants/materials, setting, methods
Among the included patients, 267 patients were classified as “½ risk of transmission” and 207 patients were classified as “1/4 risk of transmission.” We compared the chances of having a healthy baby for these two groups and studied the predictive factors for obtaining a live birth.

Main results and the role of chance
Women's characteristics at the time of first ovarian stimulation were not significantly different between P25 group and P50 group. While the mean number of embryos biopsied per couple was not significantly different between groups (9.6±8.6 vs. 8.5±7.3, p = 0.3), the mean number of healthy embryos obtained after PGT-M was significantly higher for the P25 group compared to the P50 group (5.0±4.1 vs. 3.9±3.6, p = 0.001). However, the chances of having at least one heathly child after PGT-M were not significantly different according to the P25 or P50 group (41.5% vs. 35.9% respectively, p = 0.2). We found that women’s age, AMH and CFA were predictive factors ofhaving a healthy baby. Patients aged 31 years and younger had a 45% higher chance of having a live birth than women aged 32 to 35 years (p = 0.04). Patients with AMH≥4.5ng/ml or CFA ≥22 follicles were significantly more likely to have a live birth than women with AMH ≤2.27 ng/ml or CFA &lt; 15 (OR = 1.58 (1.19-2.09) p = 0.001 and OR = 1.33 (1.01-1.75), p = 0.03 respectively).

Limitations, reasons for caution
This study is retrospective. Despite the large sample size, the findings are confined by limited coufounder adjustment and the lack of specific PGT-M comparators.

Wider implications of the findings
Age, AMH, and AFC are associated as good prognosis factors to have a live birth. The genetic mode of transmission ½ or ¼ was not found to be a predictive factor. This allows couples to make the best choice between PGT and other reproductive options (gamete donation, adoption).

Trial registration number
not applicable