Despite next-generation sequencing, which now allows for the accurate detection of segmental aneuploidies from in vitro fertilization embryo biopsies, the origin and characteristics of these aneuploidies are still relatively unknown. Using a multifocal biopsy approach (four trophectoderms [TEs] and one inner cell mass [ICM] analyzed per blastocyst; n ¼ 390), we determine the origin of the aneuploidy and the diagnostic predictive value of segmental aneuploidy detection in TE biopsies toward the ICM's chromosomal constitution. Contrary to the prevalent meiotic origin of whole-chromosome aneuploidies, we show that sub-chromosomal abnormalities in human blastocysts arise from mitotic errors in around 70% of cases. As a consequence, the positive-predictive value toward ICM configuration was significantly lower for segmental as compared to whole-chromosome aneuploidies (70.8% versus 97.18%, respectively). In order to enhance the clinical utility of reporting segmental findings in clinical TE biopsies, we have developed and clinically verified a risk stratification model based on a second TE biopsy confirmation and segmental length; this model can significantly improve the prediction of aneuploidy risk in the ICM in over 86% of clinical cases enrolled. In conclusion, we provide evidence of the predominant mitotic origin of segmental aneuploidies in preimplantation embryos and develop a risk stratification model that can help post-test genetic counseling and that facilitates the decision-making process on clinical utilization of these embryos.
STUDY QUESTION What is the clinical validity and utility of preconception Expanded Carrier Screening (ECS) application on the management of prospective parents? SUMMARY ANSWER The high detection rate of at-risk couples (ARCs) and the high proportion opting for IVF/preimplantation genetic testing (PGT) treatment demonstrate the clinical utility of ECS in the preconception space in IVF and general population. WHAT IS KNOWN ALREADY About 2–4% of couples are at risk of conceiving a child with an autosomal recessive or X-linked genetic disorder. In recent years, the increasing cost-effectiveness of genetic diagnostic techniques has allowed the creation of ECS panels for the simultaneous detection of multiple recessive disorders. Comprehensive preconception genetic screening holds the potential to significantly improve couple’s genetic risk assessment and reproductive planning to avoid detectable inheritable genetic offspring. STUDY DESIGN, SIZE, DURATION A total of 3877 individuals without a family history of genetic conditions were analyzed between January 2017 and January 2020. Of the enrolled individuals, 1212 were gamete donors and 2665 were patients planning on conceiving from both the IVF and the natural conception group. From the non-donor cohort, 1133 were analyzed as individual patients, while the remaining ones were analyzed as couples, for a total of 766 couples. PARTICIPANTS/MATERIALS, SETTING, METHODS A focused ECS panel was developed following American College of Obstetrics and Gynecology ACOG-recommended criteria (prevalence, carrier rate, severity), including highly penetrant severe childhood conditions. Couples were defined at-risk when both partners carried an autosomal recessive pathogenic/likely pathogenic variant (PLP) on the same gene or when the woman was a carrier of an X-linked PLP variant. ARC detection rate defined the clinical validity of the ECS approach. Clinical utility was evaluated by monitoring ARCs reproductive decision making. MAIN RESULTS AND THE ROLE OF CHANCE A total of 402 individuals (10.4%) showed PLP for at least one of the genes tested. Among the 766 couples tested, 173 showed one carrier partner (22.6%), whereas 20 couples (2.6%) were found to be at increased risk. Interestingly, one ARC was identified as a result of cascade testing in the extended family of an individual carrying a pathogenic variant on the Survival Of Motor Neuron 1SMN1 gene. Of the identified ARCs, 5 (0.7%) were at risk for cystic fibrosis, 5 (0.7%) for fragile X syndrome, 4 (0.5%) for spinal muscular atrophy, 4 (0.5%) for Beta-Thalassemia/Sickle Cell Anemia, 1 (0.1%) for Smith-Lemli-Opitz Syndrome and 1 (0.1%) for Duchenne/Becker Dystrophy. Fifteen ARCs were successfully followed up from both the IVF and the natural conception groups. All of these (15/15) modified their reproductive planning by undergoing ART with Preimplantation Genetic Testing for Monogenic disease and Aneuploidies (PGT-M and PGT-A). To date, 6/15 (40%) couples completed their PGT cycle with euploid/unaffected embryos achieving a pregnancy after embryo transfer and three of them have already had an unaffected baby. LIMITATIONS, REASONS FOR CAUTION The use of a limited panel of core gene-disease pairs represents a limitation on the research perspective as it can underestimate the rate of detectable carriers and ARCs in this cohort of prospective parents. Expanding the scope of ECS to a larger panel of conditions is becoming increasingly feasible, thanks to a persistent technological evolution and progressive cataloging of gene–disease associations. WIDER IMPLICATIONS OF THE FINDINGS These results highlight the potential clinical validity and utility of ECS in reducing the risk of a pregnancy affected by a detectable inheritable genetic condition. The steady reduction in the costs of genetic analyses enables the expansion of monogenic testing/screening applications at the preimplantation stage, thus, providing valid decisional support and reproductive autonomy to patients, particularly in the context of IVF. STUDY FUNDING/COMPETING INTEREST(S) No external funding was used for this study. A.C., M.F., S.C., M.P., L.G., and C.P. are employees of Igenomix Italy. C.S. is the head of the scientific board of Igenomix. TRIAL REGISTRATION NUMBER N/A.
STUDY QUESTION How well can whole chromosome copy number analysis from a single trophectoderm (TE) biopsy predict true mosaicism configurations in human blastocysts? SUMMARY ANSWER When a single TE biopsy is tested, wide mosaicism thresholds (i.e. 20–80% of aneuploid cells) increase false positive calls compared to more stringent ones (i.e. 30–70% of aneuploid cells) without improving true detection rate, while binary classification (aneuploid/euploid) provides the highest diagnostic accuracy. WHAT IS KNOWN ALREADY Next-generation sequencing-based technologies for preimplantation genetic testing for aneuploidies (PGT-A) allow the identification of intermediate chromosome copy number alterations potentially associated with chromosomal mosaicism in TE biopsies. Most validation studies are based on models mimicking mosaicism, e.g. mixtures of cell lines, and cannot be applied to the clinical interpretation of TE biopsy specimens. STUDY DESIGN, SIZE, DURATION The accuracy of different mosaicism diagnostic thresholds was assessed by comparing chromosome copy numbers in multiple samples from each blastocyst. Enrolled embryos were donated for research between June 2019 and September 2020. The Institutional Review Board at the Near East University approved the study (project: YDU/2019/70-849). Embryos showing euploid/aneuploid mosaicism (n = 53), uniform chromosomal alterations (single or multiple) (n = 25), or uniform euploidy (n = 39) in their clinical TE biopsy were disaggregated into five portions: the inner cell mass (ICM) and four TE segments. Collectively, 585 samples from 117 embryos were analysed. PARTICIPANTS/MATERIALS, SETTING, METHODS Donated blastocysts were warmed, allowed to re-expand, and disaggregated in TE portions and ICM. PGT-A analysis was performed using Ion ReproSeq PGS kit and Ion S5 sequencer (ThermoFisher). Sequencing data were blindly analysed with Ion Reporter software to estimate raw chromosome copy numbers. Intra-blastocyst comparison of copy number data was performed employing different thresholds commonly used for mosaicism detection. From copy number data, different case scenarios were created using more stringent (30–70%) or less stringent criteria (20–80%). Categorical variables were compared using the two-sample z test for proportions. MAIN RESULTS AND THE ROLE OF CHANCE When all the five biopsies from the same embryo were analysed with 30–70% thresholds, only 8.4% (n = 14/166) of patterns abnormal in the original analysis revealed a true mosaic configuration, displaying evidence of reciprocal events (3.6%, n = 6/166) or confirmation in additional biopsies (4.8%, n = 8/166), while most mosaic results (87.3% of total predicted mosaic patterns) remained confined to a single TE specimen. Conversely, uniform whole chromosome aneuploidies (28.3% of total patterns, n = 47/166) were confirmed in all subsequent biopsies in 97.9% of cases (n = 46/47). When 20–80% thresholds were employed (instead of 30–70%), the overall mosaicism rate per biopsy increased from 20.2% (n = 114/565) to 40.2% (n = 227/565). However, the use of a wider threshold range did not contribute to the detection of additional true mosaic patterns, while significantly increasing false positive mosaic patterns from 57.8% to 79.5% (n = 96/166; 95% CI = 49.9–65.4 vs n = 271/341; 95% CI = 74.8–83.6, respectively) (P < 0.00001). Moreover, the shift of the aneuploid cut-off from 70% to 80% of aneuploid cells resulted in mosaicism overcalling in the high range (50–80% of aneuploid cells), impacting the accuracy of uniform aneuploid classification. Parametric analysis of thresholds, based on multifocal analysis, revealed that a binary classification scheme with a single cut-off at a 50% level provided the highest sensitivity and specificity rates. Further analysis on technical noise distribution at the chromosome level revealed a greater impact on smaller chromosomes. LIMITATIONS, REASONS FOR CAUTION While enrolment of a population enriched in embryos showing intermediate chromosome copy numbers enhanced the evaluation of the mosaicism category compared with random sampling such study population selection is likely to lead to an overall underestimation of PGT-A accuracy compared to a general assessment of unselected clinical samples. This approach involved the analysis of aneuploidy chromosome copy number thresholds at the embryo level; future studies will need to evaluate these criteria in relation to clinical predictive values following embryo transfers for different PGT-A assays. Moreover, the study lacked genotyping-based confirmation analysis. Finally, aneuploid embryos with known meiotic partial deletion/duplication were not included. WIDER IMPLICATIONS OF THE FINDINGS Current technologies can detect low-intermediate chromosome copy numbers in preimplantation embryos but their identification is poorly correlated with consistent propagation of the anomaly throughout the embryo or with negative clinical consequences when transferred. Therefore, when a single TE biopsy is analysed, diagnosis of chromosomal mosaicism should be evaluated carefully. Indeed, the use of wider mosaicism thresholds (i.e. 20–80%) should be avoided as it reduces the overall PGT-A diagnostic accuracy by increasing the risk of false positive mosaic classification and false negative aneuploid classification. From a clinical perspective, this approach has negative consequences for patients as it leads to the potential deselection of normal embryos for transfer. Moreover, a proportion of uniform aneuploid embryos may be inaccurately categorized as high-level mosaic, with a consequent negative outcome (i.e. miscarriage) when inadvertently selected for transfer. Clinical outcomes following PGT-A are maximized when a 50% threshold is employed as it offers the most accurate diagnostic approach. STUDY FUNDING/COMPETING INTEREST(S) The study was supported by Igenomix. The authors not employed by Igenomix have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER N/A.
Desde antropología médica, como enfoque, se analiza cómo en el Centro de Salud Familiar de Putre (CESFAM) se atienden los pacientes con dolor. El trabajo de investigación que se llevó a cabo durante siete meses -septiembre de 2011 hasta febrero de 2012-permite abordar analíticamente casos de pacientes del poblado de Putre y de las localidades de precordillera y cordillera de la comuna del mismo nombre y como ellos, ante los saberes médicos plurales, hablan de dolor y lo enfrentan. Aunque el Programa Especial de Salud de los Pueblos Indígenas (PESPI) incluye médicos aymara en el equipo de trabajo del CESFAM, cada etnomedicina maneja el dolor en su complejidad desde su perspectiva profesional en el campo de la salud intercultural, transformando a través de las prácticas terapéuticas plurales esa ambigüedad, que el dolor genera, en la vida del sujeto que sufre. El dolor del paciente aymara se incluye en el campo de la salud intercultural, pero la condición íntima y privada del sujeto se hace pública y política cuando se maneja a nivel institucional.Palabras claves: dolor, salud intercultural, prácticas terapéuticas integradas. Through the medical anthropology's perspective we analyze how are attended patients with pain by the Center of familiar health of Putre (CESFAM). The field research, performed from September of 2011 to February of 2012, allowed to us to analyze the cases about patients of Putre and other about patients of pre cordillera's and cordillera's villages. They speak about pain and used to take care about it moving around different medical knowledge. The especial program of native's populations includes aymara's therapists in the CESFAM's team. Every etnomedicine manages pain in its complexity from its professional perspective inside the intercultural health's field, transforming trough the therapeutics and plurals practices this ambiguity that pain causes in the life IntroducciónCuando hablamos de dolor siempre resulta difícil entender, en términos específicos, lo que significa para los pacientes que hablan de su malestar. Por esta razón necesitamos referirnos a las raíces etimológicas de nuestros idiomas que desde el latín nos permiten encontrar el sentido de nuestro lenguaje, el mismo que utilizamos para describir lo que pasa cuando nos enfermamos. En italiano como en castellano la palabra "dolor" nace de la raíz Dol-éo (Devoto 1995) que indica algo que se nos quiebra adentro. El dolor surge cuando algo queda quebrado en nuestro cuerpo y en nuestra vida. Para referirnos al dolor muchas veces hablamos en términos de malestar, sufrimiento, padecimiento y la palabra "sufrir" etimológicamente se refiere a Sub-ferre (Devoto 1995) "conllevar", "aguantar".Esta diferencia entre estas dos palabras, las que los pacientes utilizan cuando hablan de su condición de sufrimiento, define una separación que la biomedicina siempre adopta. El dolor es algo físico, en cambio el sufrimiento se refiere a cómo nos sentimos. La antropología médica critica el pensamiento maniqueo que opera una separación entre alma y cue...
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