Combined achondroplasia and short stature homeobox-containing (SHOX) gene deletion in a Danish infant.

Short stature or shortening of the limbs can be the result of a variety of genetic variants. Achondroplasia is the most common cause of disproportionate short stature and is caused by pathogenic variants in the fibroblast growth factor receptor 3 gene (FGFR3). Short stature homeobox (SHOX) deficiency is caused by loss or defects of the SHOX gene or its enhancer region. It is associated with a spectrum of phenotypes ranging from normal stature to Léri-Weill dyschondrosteosis characterized by mesomelia and short stature or the more severe Langer mesomelic dysplasia in case of biallelic SHOX deficiency. Little is known about the interactions and phenotypic consequences of achondroplasia in combination with SHOX deficiency, as the literature on this subject is scarce, and no genetically confirmed clinical reports exist. We present the clinical findings in an infant girl with concurrent achondroplasia and SHOX deficiency. We conclude that the clinical findings in infancy are phenotypically compatible with achondroplasia, with no features of the SHOX deficiency evident. This may change over time, as some features of SHOX deficiency only become evident later in life.

Preimplantation genetic testing in two Danish couples affected by Peutz-Jeghers syndrome.

BACKGROUND: Guidelines from the European Hereditary Tumor Group as well as The Danish National Guidelines for Peutz-Jeghers Syndrome (PJS) state that both prenatal diagnosis and preimplantation genetic testing for monogenic disorders (PGT-M) should be offered to patients with PJS. However, only a few cases resulting in viable pregnancies have been published. OBJECTIVE: We present two cases of PJS patients going through PGT-M for PJS. We highlight the awareness of this possibility and discuss the technical and ethical challenges of performing PGT-M for PJS. METHODS AND RESULTS: Case 1: A 36-year-old male with PJS and his partner were referred for genetic counseling. The patient carried a pathogenic de novo variant in STK11. After a terminated pregnancy of a fetus carrying the same pathogenic variant, microsatellite polymorphic marker analysis was established, and the patient was offered PGT-M. The female partner of the patient gave birth to a healthy boy after five years of fertility treatment. Case 2: A 35-year-old female with PJS and her partner were referred for genetic counseling. She carried an inherited pathogenic STK11 variant. The couple was offered PGT-M. Genetic testing of the embryos was performed using microsatellite polymorphic markers. After two rounds of oocyte extraction a blastocyst predicted not to be affected by PJS was identified. The blastocyst was transferred; however, this did not result in a viable pregnancy. CONCLUSIONS: PGT-M can be offered to patients with PJS. The process may be long and filled with ethical dilemmas requiring patients to be motivated and persistent.

Patients' choices and opinions on chorionic villous sampling and non-invasive alternatives for prenatal testing following preimplantation genetic testing for hereditary disorders: A cross-sectional questionnaire study.

OBJECTIVE: The aim of this study was to investigate choices of and reasoning behind chorionic villous sampling and opinions on non-invasive prenatal testing among women and men achieving pregnancy following preimplantation genetic testing (PGT) for hereditary disorders. METHODS: A questionnaire was electronically submitted to patients who had achieved a clinical pregnancy following PGT at the Center for Preimplantation Genetic Testing, Aalborg University Hospital, Denmark, between 2017 and 2020. RESULTS: Chorionic villous sampling was declined by approximately half of the patients. The primary reason for declining was the perceived risk of miscarriage due to the procedure. Nine out of 10 patients responded that they would have opted for a non-invasive prenatal test if it had been offered. Some patients were not aware that the nuchal translucency scan offered to all pregnant women in the early second trimester only rarely provides information on the hereditary disorder for which PGT was performed. CONCLUSION: Improved counseling on the array of prenatal tests and screenings available might be required to assist patients in making better informed decisions regarding prenatal testing. Non-invasive prenatal testing is welcomed by the patients and will likely increase the number of patients opting for confirmatory prenatal testing following PGT for hereditary disorders.

[Preimplantation genetic testing].

Preimplantation genetic testing (PGT) for known familial monogenetic disease (PGT-M) or structural chromosomal rearrangements (PGT-SR) has evolved into a well-established alternative to prenatal diagnosis. PGT significantly reduces the risk of a pregnancy with an affected foetus. Screening for aneuploidy (PGT-A) used as an add-on to standard IVF treatment of infertile couples is widely used internationally, although its benefit is highly debated. PGT combines genetic counselling and testing with assisted reproductive technology including ovarian stimulation, egg retrieval, and embryo biopsy, as discussed in this review.

A systematic review on concurrent aneuploidy screening and preimplantation genetic testing for hereditary disorders: What is the prevalence of aneuploidy and is there a clinical effect from aneuploidy screening?

INTRODUCTION: In assisted reproductive technology, aneuploidy is considered a primary cause of failed embryo implantation. This has led to the implementation of preimplantation genetic testing for aneuploidy in some clinics. The prevalence of aneuploidy and the use of aneuploidy screening during preimplantation genetic testing for inherited disorders has not previously been reviewed. Here, we systematically review the literature to investigate the prevalence of aneuploidy in blastocysts derived from patients carrying or affected by an inherited disorder, and whether screening for aneuploidy improves clinical outcomes. MATERIAL AND METHODS: PubMed and Embase were searched for articles describing preimplantation genetic testing for monogenic disorders and/or structural rearrangements in combination with preimplantation genetic testing for aneuploidy. Original articles reporting aneuploidy rates at the blastocyst stage and/or clinical outcomes (positive human chorionic gonadotropin, gestational sacs/implantation rate, fetal heartbeat/clinical pregnancy, ongoing pregnancy, miscarriage, or live birth/delivery rate on a per transfer basis) were included. Case studies were excluded. RESULTS: Of the 26 identified studies, none were randomized controlled trials, three were historical cohort studies with a reference group not receiving aneuploidy screening, and the remaining were case series. In weighted analysis, 34.1% of 7749 blastocysts were aneuploid. Screening for aneuploidy reduced the proportion of embryos suitable for transfer, thereby increasing the risk of experiencing a cycle without transferable embryos. In pooled analysis the percentage of embryos suitable for transfer was reduced from 57.5% to 37.2% following screening for aneuploidy. Among historical cohort studies, one reported significantly improved pregnancy and birth rates but did not control for confounding, one did not report any statistically significant difference between groups, and one properly designed study concluded that preimplantation genetic testing for aneuploidy enhanced the chance of achieving a pregnancy while simultaneously reducing the chance of miscarriage following single embryo transfer. CONCLUSIONS: On average, aneuploidy is detected in 34% of embryos when performing a single blastocyst biopsy derived from patients carrying or affected by an inherited disorder. Accordingly, when screening for aneuploidy, the risk of experiencing a cycle with no transferable embryos increases. Current available data on the clinical effect of preimplantation genetic testing for aneuploidy performed concurrently with preimplantation genetic testing for inherited disorders are sparse, rendering the clinical effect from preimplantation genetic testing for aneuploidy difficult to access.

[Preimplantation genetic testing for aneuploidy].

This review summarises the current knowledge on preimplantation genetic testing for aneuploidy (PGT-A). Selection and transfer of euploid embryos aim to improve live birth rate (LBR) per embryo transfer, but fluorescence in situ hybridisation-based PGT-A and biopsy of cleavage stage embryos in the 2000s was a disappointment, as studies revealed a reduced LBR. Today, PGT-A includes comprehensive chromosome screening primarily of blastocyst biopsies. The benefit of PGT-A is highly debated: some suggest improved treatment outcome, while others claim, that the procedure is not cost-effective.

[Preimplantation genetic diagnosis].

In Denmark, preimplantation genetic diagnosis (PGD) is offered within the public healthcare to families with a known risk of an inherited disease in a child - as an alternative to prenatal diagnosis. It is a well-established technique with rather well-described perinatal- and neonatal outcomes, being comparable to what is seen following in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). The most common strategy is now to perform trophectoderm biopsy and then vitrify, while the diagnostic test is performed. Until 2013, 134 children have been born following PGD. Today, the clinical pregnancy rates are comparable to those following IVF/ICSI.