Pathogenic PDE12 variants impair mitochondrial RNA processing causing neonatal mitochondrial disease.

Pathogenic variants in either the mitochondrial or nuclear genomes are associated with a diverse group of human disorders characterized by impaired mitochondrial function. Within this group, an increasing number of families have been identified, where Mendelian genetic disorders implicate defective mitochondrial RNA biology. The PDE12 gene encodes the poly(A)-specific exoribonuclease, involved in the quality control of mitochondrial non-coding RNAs.

Fetal Presentation of MYRF-Related Cardiac Urogenital Syndrome: An Emerging and Challenging Prenatal Diagnosis.

Purpose: MYRF-related cardiac-urogenital syndrome (MYRF-CUGS) is a rare condition associated with heterozygous MYRF variants. The description of MYRF-CUGS phenotype is mostly based on postnatal cases and 36 affected individuals have been published so far. We aim now to delineate the prenatal phenotype of MYRF-CUGS by reporting clinical data from fetuses and neonates with a pathogenic MYRF variant.

Use of Prenatal Exome Sequencing: Opinion Statement of the French Federation of Human Genetics Working Group.

Objective: Prenatal whole exome sequencing (pES) is increasingly prescribed for fetuses with ultrasound anomalies. Starting from the local French prenatal medicine practice, healthcare system and legal landscape, we aimed to address the broad medical and ethical issues raised by the use of pES for women and couples as well as for prenatal care providers.

Method: The French Federation of Human Genetics established a working group composed of clinicians and biologists from all over France to discuss pES challenges.

Inferring disease course from differential exon usage in the wide titinopathy spectrum.

Objective: Biallelic titin truncating variants (TTNtv) have been associated with a wide phenotypic spectrum, ranging from complex prenatal muscle diseases with dysmorphic features to adult-onset limb-girdle muscular dystrophy, with or without cardiac involvement. Given the size and complexity of TTN, reaching an unequivocal molecular diagnosis and precise disease prognosis remains challenging.

Methods: In this case series, 12 unpublished cases and one already published case with biallelic TTNtv were collected from multiple international medical centers between November 2022 and September 2023.

The phenotype of MEGF8-related Carpenter syndrome (CRPT2) is refined through the identification of eight new patients.

Carpenter syndrome (CRPTS) is a rare autosomal recessive condition caused by biallelic variants in genes that encode negative regulators of hedgehog signalling (RAB23 [CRPT1] or, more rarely, MEGF8 [CRPT2]), and is characterised by craniosynostosis, polysyndactyly, and other congenital abnormalities. We describe a further six families comprising eight individuals with MEGF8-associated CRPT2, increasing the total number of reported cases to fifteen, and refine the phenotype of CRPT2 compared to CRPT1. The core features of craniosynostosis, polysyndactyly and (in males) cryptorchidism are almost universal in both CRPT1 and CRPT2.

A cell fate decision map reveals abundant direct neurogenesis bypassing intermediate progenitors in the human developing neocortex.

The human neocortex has undergone strong evolutionary expansion, largely due to an increased progenitor population, the basal radial glial cells. These cells are responsible for the production of a diversity of cell types, but the successive cell fate decisions taken by individual progenitors remain unknown. Here we developed a semi-automated live/fixed correlative imaging method to map basal radial glial cell division modes in early fetal tissue and cerebral organoids.

Expanding the phenotypic spectrum of LIG4 pathogenic variations: neuro-histopathological description of 4 fetuses with stenosis of the aqueduct.

Severe ventriculomegaly is a rare congenital brain defect, usually detected in utero, of poor neurodevelopmental prognosis. This ventricular enlargement can be the consequence of different mechanisms: either by a disruption of the cerebrospinal fluid circulation or abnormalities of its production/absorption. The aqueduct stenosis is one of the most frequent causes of obstructive ventriculomegaly, however, fewer than 10 genes have been linked to this condition and molecular bases remain often unknown.

Differential alternative splicing analysis links variation in ZRSR2 to a novel type of oral-facial-digital syndrome.

Purpose: Oral-facial-digital (OFD) syndromes are genetically heterogeneous developmental disorders, caused by pathogenic variants in genes involved in primary cilia formation and function. We identified a previously undescribed type of OFD with brain anomalies, ranging from alobar holoprosencephaly to pituitary anomalies, in 6 unrelated families.

Methods: Exome sequencing of affected probands was supplemented with alternative splicing analysis in patient and control lymphoblastoid and fibroblast cell lines, and primary cilia structure analysis in patient fibroblasts.

Neu Laxova syndrome and megacystis in the first trimester: Broadening the fetal phenotype.

Neu Laxova syndrome (NLS) is a rare and lethal congenital disorder characterized by severe intra-uterine growth retardation (IUGR), ichthyosis, abnormal facial features, limb abnormalities with arthrogryposis and a wide spectrum of severe malformations of the central nervous system (CNS). NLS is due to biallelic variants in three genes previously involved in serine-deficiency disorders (PHGDH, PSAT1 and PSPH), extending the phenotypic spectrum of these disorders.

Prenatal Diagnosis of Primrose Syndrome.

Primrose syndrome is a very rare congenital malformation. Symptoms of this disorder may appear during childhood, but the diagnosis is identified in adulthood in the majority of cases. The prenatal diagnosis of Primrose syndrome is not developed in the literature.

Clinico-biological refinement of BCL11B-related disorder and identification of an episignature: A series of 20 unreported individuals.

Purpose: BCL11B-related disorder (BCL11B-RD) arises from rare genetic variants within the BCL11B gene, resulting in a distinctive clinical spectrum encompassing syndromic neurodevelopmental disorder, with or without intellectual disability, associated with facial features and impaired immune function. This study presents an in-depth clinico-biological analysis of 20 newly reported individuals with BCL11B-RD, coupled with a characterization of genome-wide DNA methylation patterns of this genetic condition.

Methods: Through an international collaboration, clinical and molecular data from 20 individuals were systematically gathered, and a comparative analysis was conducted between this series and existing literature.

AI-based diagnosis in mandibulofacial dysostosis with microcephaly using external ear shapes.

Introduction: Mandibulo-Facial Dysostosis with Microcephaly (MFDM) is a rare disease with a broad spectrum of symptoms, characterized by zygomatic and mandibular hypoplasia, microcephaly, and ear abnormalities. Here, we aimed at describing the external ear phenotype of MFDM patients, and train an Artificial Intelligence (AI)-based model to differentiate MFDM ears from non-syndromic control ears (binary classification), and from ears of the main differential diagnoses of this condition (multi-class classification): Treacher Collins (TC), Nager (NAFD) and CHARGE syndromes.

Methods: The training set contained 1,592 ear photographs, corresponding to 550 patients.

De novo missense variants in phosphatidylinositol kinase PIP5KIγ underlie a neurodevelopmental syndrome associated with altered phosphoinositide signaling.

Phosphoinositides (PIs) are membrane phospholipids produced through the local activity of PI kinases and phosphatases that selectively add or remove phosphate groups from the inositol head group. PIs control membrane composition and play key roles in many cellular processes including actin dynamics, endosomal trafficking, autophagy, and nuclear functions. Mutations in phosphatidylinositol 4,5 bisphosphate [PI(4,5)P2] phosphatases cause a broad spectrum of neurodevelopmental disorders such as Lowe and Joubert syndromes and congenital muscular dystrophy with cataracts and intellectual disability, which are thus associated with increased levels of PI(4,5)P2.

Investigating genotype-to-phenotype correlation in CHARGE syndrome by deep phenotyping and multiparametric clustering.

CHARGE syndrome, due to CHD7 pathogenic variations, is an autosomal dominant disorder characterized by a large spectrum of severity. Despite the great number of variations reported, no clear genotype-to-phenotype correlation has been reported. Unsupervised machine learning and clustering was undertaken using a retrospective cohort of 42 patients, after deep radiologic and clinical phenotyping, to establish genotype-phenotype correlation for CHD7-related CHARGE syndrome.