Unexpected High Prevalence of Focal Facial Dermal Dysplasia (FFDD) Type IV Is Linked to a Founder Effect in the Belgian Population.

Focal facial dermal dysplasia (FFDD) type IV is a rare inherited facial defect caused by biallelic variants in CYP26C1. This study reports two novel Belgian FFDD type IV cases, both homozygous for a recurrent CYP26C1 frameshift variant, with a common 700 kb haplotype, indicating a founder effect.

A heatmap for expected cumulative live birth rate in preimplantation genetic testing for monogenic disorders and chromosomal structural rearrangements.

Purpose: Our objective is to predict the cumulative live birth rate (CLBR) and identify the specific subset within the population undergoing preimplantation genetic testing for monogenic disorders (PGT-M) and chromosomal structural rearrangements (PGT-SR) which is likely to exhibit a diminished expected CLBR based on various patient demographics.

Methods: We performed a single-centre retrospective cohort study including 1522 women undergoing 3130 PGT cycles at a referral centre for PGT. A logistic regression analysis was performed to predict the CLBR per ovarian stimulation in women undergoing PGT-M by polymerase chain reaction (PCR) or single-nucleotide polymorphism (SNP) array, and in women undergoing PGT-SR by SNP array, array comparative genomic hybridization (CGH) or next-generation sequencing (NGS).

Pathogenic variants in HGF give rise to childhood-to-late onset primary lymphoedema by loss of function.

Developmental and functional defects in the lymphatic system are responsible for primary lymphoedema (PL). PL is a chronic debilitating disease caused by increased accumulation of interstitial fluid, predisposing to inflammation, infections and fibrosis. There is no cure, only symptomatic treatment is available.

Prenatal phenotype of a homozygous nonsense MPDZ variant in a fetus with severe congenital hydrocephalus.

The fetal phenotype of MPDZ-associated congenital hydrocephalus type 2 with or without brain or eye anomalies (HYC2) (OMIM 615219) is not well described in the literature. The present case shows not previously published clinical fetal features that are detected during routine second trimester ultrasound screening at 21 weeks of gestation such as bilateral ventriculomegaly, lean cavum septum pellucidum, suspicion of hypoplastic corpus callosum, and suspicion of gyration disorder with normal fossa posterior. Combination of clinical features and a gene panel for congenital malformation syndromes detected a homozygous, likely pathogenic nonsense variant in the MPDZ gene.

Cleavage-stage or blastocyst-stage embryo biopsy has no impact on growth and health in children up to 2 years of age.

Background: Studies show conflicting results on neonatal outcomes following embryo biopsy for PGT, primarily due to small sample sizes and/or heterogeneity in the timing of embryo biopsy (day 3; EBD3 or day 5/6; EBD5) and type of embryo transfer. Even fewer data exist on the impact on children's health beyond the neonatal period. This study aimed to explore outcomes in children born after EBD3 or EBD5 followed by fresh (FRESH) or frozen-thawed embryo transfer (FET).

Searching for a sense of closure: parental experiences of recontacting after a terminated pregnancy for congenital malformations.

Rapid advances in genetic testing have improved the probability of successful genetic diagnosis. For couples who undergo a termination of pregnancy (TOP) due to foetal congenital malformations, these techniques may reveal the underlying cause and satisfy parents' need to know. The aim of this qualitative descriptive research study was to explore couples' experience of being recontacted after a congenital malformation-related TOP, as well as their reasons for participation.

Congenital hydrocephalus: new Mendelian mutations and evidence for oligogenic inheritance.

Background: Congenital hydrocephalus is characterized by ventriculomegaly, defined as a dilatation of cerebral ventricles, and thought to be due to impaired cerebrospinal fluid (CSF) homeostasis. Primary congenital hydrocephalus is a subset of cases with prenatal onset and absence of another primary cause, e.g.

Impact of embryo vitrification on children's health, including growth up to two years of age, in comparison with results following a fresh embryo transfer.

Objective: To assess health outcomes, including growth up to 2 years of age, in children born after embryo vitrification in comparison with children born after fresh embryo transfer.

Design: A prospective cohort study.

Setting: A single-center university hospital.

Overlapping cortical malformations in patients with pathogenic variants in and .

Background: Malformations of cortical development (MCDs) have been reported in a subset of patients with pathogenic heterozygous variants in or , genes which encode for subunits of the N-methyl-D-aspartate receptor (NMDAR). The aim of this study was to further define the phenotypic spectrum of NMDAR-related MCDs.

Methods: We report the clinical, radiological and molecular features of 7 new patients and review data on 18 previously reported individuals with NMDAR-related MCDs.

Analysis of parental contribution for aneuploidy detection (APCAD): a novel method to detect aneuploidy and mosaicism in preimplantation embryos.

Research Question: Can (mosaic) aneuploidy be reliably detected in preimplantation embryos after multiple displacement amplification and single nucleotide polymorphism detection, independent of haplotyping and copy number detection, with a new method 'analysis of parental contribution for aneuploidy detection' or 'APCAD'?

Design: This method is based on the maternal contribution, a parameter that reflects the proportion of DNA that is of maternal origin for a given chromosome or chromosome segment. A maternal contribution deviating from 50% for autosomes is strongly indicative of a (mosaic) chromosomal anomaly. The method was optimized using cell mixtures with varying ratios of euploid and aneuploid (47,XY,+21) lymphocytes.

A prenatal case of lissencephaly with cerebellar hypoplasia: New mutation in RELN gene.

Reelinopathies cause a distinctive lissencephaly type associated with cerebellar hypoplasia. To help further management, we wanted to report here the first prenatal diagnosis due to a homozygous inherited reelinopathy.

Implementation of fetal clinical exome sequencing: Comparing prospective and retrospective cohorts.

Purpose: We compared the diagnostic yield of fetal clinical exome sequencing (fCES) in prospective and retrospective cohorts of pregnancies presenting with anomalies detected using ultrasound. We evaluated factors that led to a higher diagnostic efficiency, such as phenotypic category, clinical characterization, and variant analysis strategy.

Methods: fCES was performed for 303 fetuses (183 ongoing and 120 ended pregnancies, in which chromosomal abnormalities had been excluded) using a trio/duo-based approach and a multistep variant analysis strategy.

Phenotypes and genotypes in non-consanguineous and consanguineous primary microcephaly: High incidence of epilepsy.

Background: Primary microcephaly (PM) is defined as a significant reduction in occipitofrontal circumference (OFC) of prenatal onset. Clinical and genetic heterogeneity of PM represents a diagnostic challenge.

Methods: We performed detailed phenotypic and genomic analyses in a large cohort (n = 169) of patients referred for PM and could establish a molecular diagnosis in 38 patients.

Parameters of poor prognosis in preimplantation genetic testing for monogenic disorders.

Study Question: What is the likelihood of success of a single cycle of preimplantation genetic testing for monogenic disorders (PGT-M), measured as the cumulative live birth rate (CLBR) and based on various patient demographics?

Summary Answer: For all women aged ≤40 years, the CLBR was at least 10% when the number of oocytes was ≥7 (range 10-30%) or was at least 5% when the number of oocytes was ≥3 (range 5-17%).

What Is Known Already: The number of oocytes is significantly associated with the number of embryos for genetic testing and the clinical outcome in PGT-M. Embryos diagnosed as affected or embryos that remain without diagnosis cannot be used for embryo transfer.

PREIMPLANTATION GENETIC TESTING: Clinical experience of preimplantation genetic testing.

Thirty years of rapid technological advances in the field of genetic testing and assisted reproduction have reshaped the procedure of preimplantation genetic testing (PGT). The development of whole genome amplification and genome-wide testing tools together with the implementation of optimal hormonal stimulation protocols and more efficient cryopreservation methods have led to more accurate diagnoses and improved clinical outcomes. In addition, the shift towards embryo biopsy at day 5/6 has changed the timeline of a typical PGT clinical procedure.

Multiple vitrification-warming and biopsy procedures on human embryos: clinical outcome and neonatal follow-up of children.

Study Question: Does double vitrification and warming of human blastocysts having undergone biopsy once or twice have an impact on the clinical outcome?

Summary Answer: The clinical pregnancy rate obtained with double vitrification single biopsy blastocysts was comparable to that obtained with single vitrification single biopsy blastocysts in our center in the same time period (46%; 2016-2018), whereas that obtained with double-vitrified double-biopsied blastocysts seemed lower and will need further study.

What Is Known Already: Genetic testing on cryopreserved unbiopsied embryos involves two cryopreservation procedures. Retesting of failed/inconclusive-diagnosed blastocysts inevitably involves a second round of biopsy and a second round of vitrification as well.

Chromosomal abnormalities after ICSI in relation to semen parameters: results in 1114 fetuses and 1391 neonates from a single center.

Study Question: Is there a relationship between karyotype abnormalities in fetuses and children conceived by ICSI and their father's semen parameters?

Summary Answer: The de novo chromosomal abnormality rate in pre- and postnatal karyotypes of ICSI offspring was higher than in the general population and related to fathers' sperm parameters.

What Is Known Already: Several studies have reported a higher rate of de novo chromosomal anomalies in ICSI fetuses but recent data from large cohorts are limited. Overall, reported prevalences of non-inherited karyotype aberrations are increased in fetuses conceived after ICSI and vary between 1.

Defining the phenotypical spectrum associated with variants in .

Background: Variants in genes belonging to the tubulin superfamily account for a heterogeneous spectrum of brain malformations referred to as tubulinopathies. Variants in have been reported in 10 patients with a broad spectrum of brain imaging features, ranging from a normal cortex to polymicrogyria, while one patient has been reported with progressive atrophy of the cerebellar vermis.

Methods: In order to further refine the phenotypical spectrum associated with , clinical and imaging features of 12 patients with pathogenic variants, recruited via the international network of the authors, were reviewed.

An ACVRL1 gene mutation presenting as vein of Galen malformation at prenatal diagnosis.

Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disease. The diagnostic criteria of HHT, or Curaçao criteria, include the following: recurrent epistaxis or nighttime nose bleeding, mucocutaneous telangiectases, visceral arteriovenous malformation, or an appropriate family history. The diagnosis is classified as definite if three criteria are present, possible if two criteria are present, and unlikely if only one is present.

ERCC2 mutations in two siblings with a severe trichothiodystrophy phenotype.

Background: Trichothiodystrophy (TTD) describes a group of rare genetic disorders of DNA repair, characterized by sulphur-deficient hair, skin anomalies and systemic complications like preterm delivery, neurological impairment, haematological and ophthalmological abnormalities and life-threatening infections.

Objectives: The aim of this case report was to investigate the contribution of the gene mutation to the phenotype.

Methods: We describe the clinical and molecular characteristics of a family with two TTD-affected siblings who died before the age of 2 years.