Pathogenic RAB34 variants impair primary cilium assembly and cause a novel oral-facial-digital syndrome.

Oral-facial-digital syndromes (OFDS) are a group of clinically and genetically heterogeneous disorders characterized by defects in the development of the face and oral cavity along with digit anomalies. Pathogenic variants in over 20 genes encoding ciliary proteins have been found to cause OFDS through deleterious structural or functional impacts on primary cilia. We identified by exome sequencing bi-allelic missense variants in a novel disease-causing ciliary gene RAB34 in four individuals from three unrelated families. Affected individuals presented a novel form of OFDS (OFDS-RAB34) accompanied by cardiac, cerebral, skeletal and anorectal defects. RAB34 encodes a member of the Rab GTPase superfamily and was recently identified as a key mediator of ciliary membrane formation. Unlike many genes required for cilium assembly, RAB34 acts selectively in cell types that use the intracellular ciliogenesis pathway, in which nascent cilia begin to form in the cytoplasm. We find that the protein products of these pathogenic variants, which are clustered near the RAB34 C-terminus, exhibit a strong loss of function. Although some variants retain the ability to be recruited to the mother centriole, cells expressing mutant RAB34 exhibit a significant defect in cilium assembly. While many Rab proteins have been previously linked to ciliogenesis, our studies establish RAB34 as the first small GTPase involved in OFDS and reveal the distinct clinical manifestations caused by impairment of intracellular ciliogenesis.

Developmental interplay between transcriptional alterations and a targetable cytokine signaling dependency in pediatric ETO2::GLIS2 leukemia.

BACKGROUND: Several fusion oncogenes showing a higher incidence in pediatric acute myeloid leukemia (AML) are associated with heterogeneous megakaryoblastic and other myeloid features. Here we addressed how developmental mechanisms influence human leukemogenesis by ETO2::GLIS2, associated with dismal prognosis. METHODS: We created novel ETO2::GLIS2 models of leukemogenesis through lentiviral transduction and CRISPR-Cas9 gene editing of human fetal and post-natal hematopoietic stem/progenitor cells (HSPCs), performed in-depth characterization of ETO2::GLIS2 transformed cells through multiple omics and compared them to patient samples. This led to a preclinical assay using patient-derived-xenograft models to test a combination of two clinically-relevant molecules. RESULTS: We showed that ETO2::GLIS2 expression in primary human fetal CD34+ hematopoietic cells led to more efficient in vivo leukemia development than expression in post-natal cells. Moreover, cord blood-derived leukemogenesis has a major dependency on the presence of human cytokines, including IL3 and SCF. Single cell transcriptomes revealed that this cytokine environment controlled two ETO2::GLIS2-transformed states that were also observed in primary patient cells. Importantly, this cytokine sensitivity may be therapeutically-exploited as combined MEK and BCL2 inhibition showed higher efficiency than individual molecules to reduce leukemia progression in vivo. CONCLUSIONS: Our study uncovers an interplay between the cytokine milieu and transcriptional programs that extends a developmental window of permissiveness to transformation by the ETO2::GLIS2 AML fusion oncogene, controls the intratumoral cellular heterogeneity, and offers a ground-breaking therapeutical opportunity by a targeted combination strategy.

Refining the phenotype of SINO syndrome: A comprehensive cohort report of 14 novel cases.

PURPOSE: Spastic paraplegia, intellectual disability, nystagmus, and obesity syndrome (SINO) is a rare autosomal dominant condition caused by heterozygous variants in KIDINS220. A total of 12 individuals are reported, comprising 8 with SINO and 4 with an autosomal recessive condition attributed to biallelic KIDINS220 variants. METHODS: In our international cohort, we have included 14 individuals, carrying 13 novel pathogenic KIDINS220 variants in heterozygous form. We assessed the clinical and molecular data of our cohort and previously reported individuals and, based on functional experiments, reached a better understanding of the pathogenesis behind the KIDINS220-related disease. RESULTS: Using fetal tissue and in vitro assays, we demonstrate that the variants generate KIDINS220 truncated forms that mislocalize in punctate intracellular structures, with decreased levels of the full-length protein, suggesting a trans-dominant negative effect. A total of 92% had their diagnosis within 3 years, with symptoms of developmental delay, spasticity, hypotonia, lack of eye contact, and nystagmus. We identified a KIDINS220 variant associated with fetal hydrocephalus and show that 58% of examined individuals present brain ventricular dilatation. We extend the phenotypic spectrum of SINO syndrome to behavioral manifestations not previously highlighted. CONCLUSION: Our study provides further insights into the clinical spectrum, etiology, and predicted functional impact of KIDINS220 variants.

Improved prenatal assessment of kidney disease using multiple ultrasound features.

BACKGROUND AND HYPOTHESIS: Congenital anomalies of the kidney and the urinary tract (CAKUT), often discovered in utero, cover a wide spectrum of outcomes ranging from normal postnatal kidney function to fetal death. The current ultrasound workup does not allow for an accurate assessment of the outcome. The present study aimed to significantly improve the ultrasound-based prediction of postnatal kidney survival in CAKUT. METHODS: Histological analysis of kidneys of 15 CAKUT fetuses was performed to better standardize the ultrasound interpretation of dysplasia and cysts. Ultrasound images of 140 CAKUT fetuses with 2-year postnatal follow-up were annotated for amniotic fluid volume and kidney number, size, dysplasia and/or cysts using standardized ultrasound readout. Association of ultrasound features and clinical data (sex and age at diagnosis) with postnatal kidney function was studied using logistic regression. Amniotic fluid proteome associated to kidney dysplasia or cysts was characterized by mass spectrometry. RESULTS: Histologically, poor ultrasound corticomedullary differentiation was associated to dysplastic lesions and ultrasound hyperechogenicity was associated to the presence of microcysts. Of all ultrasound and clinical parameters, reduced amniotic volume, dysplasia and cysts were the best predictors of poor outcome (Odd ratio = 57 [95%CI: 11-481], 20 [3-225] and 7 [1-100], respectively). Their combination into an algorithm improved prediction of postnatal kidney function compared to amniotic volume alone (area under the ROC curve = 0.92 [0.86-0.98] in a 10-fold cross validation). Dysplasia and cysts were correlated (Cramer's V coefficient = 0.44, p<0.0001), but amniotic fluid proteome analysis revealed that they had distinct molecular origin (extracellular matrix and cell contacts versus cellular death, respectively), probably explaining the additivity of their predictive performances. CONCLUSION: Antenatal clinical advice for CAKUT pregnancies can be improved by a more standardized and combined interpretation of ultrasound data.

The First Fetal Case of Shwachman-Diamond Syndrome Mimicking Vascular Growth Restriction.

Shwachman-Diamond Syndrome (SDS) is a rare autosomal recessive genetic condition with 90% of cases associated with biallelic pathogenic variants in the Shwachman-Bodian-Diamond Syndrome (SBDS) gene on chromosome 7q.11.21. SDS belongs to ribosomopathies since SBDS gene encodes a protein involved in ribosomal maturation. Its phenotypic postnatal hallmark features include growth delay, bone marrow failure, exocrine pancreatic insufficiency, and skeletal abnormalities. We report a first fetal case of Shwachman-Diamond syndrome and extend its phenotype before birth. The clinical features mimicked vascular growth restriction with FGR and shortened long bones, associated with abnormal Doppler indices. Non-restricted fetal autopsy after termination of pregnancy allowed deep phenotyping disclosing the features of fetal skeletal dysplasia. Post-fetopathological trio exome sequencing identified biallelic pathogenic variants in the SBDS gene. Genotype-phenotype correlations confirmed the diagnosis and enabled an adequate genetic counseling of the parents. Our case is another example of the positive impact of fetal autopsy coupled with post-fetopathological genomic studies, even in the cases that were hitherto classified as maternal or fetal vascular malperfusion.

Clinical, genetic and biochemical signatures of RBP4-related ocular malformations.

BACKGROUND: The retinoic acid (RA) pathway plays a crucial role in both eye morphogenesis and the visual cycle. Individuals with monoallelic and biallelic pathogenic variants in retinol-binding protein 4 (RBP4), encoding a serum retinol-specific transporter, display variable ocular phenotypes. Although few families have been reported worldwide, recessive inherited variants appear to be associated with retinal degeneration, while individuals with dominantly inherited variants manifest ocular development anomalies, mainly microphthalmia, anophthalmia and coloboma (MAC). METHODS: We report here seven new families (13 patients) with isolated and syndromic MAC harbouring heterozygous RBP4 variants, of whom we performed biochemical analyses. RESULTS: For the first time, malformations that overlap the clinical spectrum of vitamin A deficiency are reported, providing a link with other RA disorders. Our data support two distinct phenotypes, depending on the nature and mode of inheritance of the variants: dominantly inherited, almost exclusively missense, associated with ocular malformations, in contrast to recessive, mainly truncating, associated with retinal degeneration. Moreover, we also confirm the skewed inheritance and impact of maternal RBP4 genotypes on phenotypical expression in dominant forms, suggesting that maternal RBP4 genetic status and content of diet during pregnancy may modify MAC occurrence and severity. Furthermore, we demonstrate that retinol-binding protein blood dosage in patients could provide a biological signature crucial for classifying RBP4 variants. Finally, we propose a novel hypothesis to explain the mechanisms underlying the observed genotype-phenotype correlations in RBP4 mutational spectrum. CONCLUSION: Dominant missense variants in RBP4 are associated with MAC of incomplete penetrance with maternal inheritance through a likely dominant-negative mechanism.

Bi-allelic variants in WNT7B disrupt the development of multiple organs in humans.

BACKGROUND: Pulmonary hypoplasia, Diaphragmatic anomalies, Anophthalmia/microphthalmia and Cardiac defects delineate the PDAC syndrome. We aim to identify the cause of PDAC syndrome in patients who do not carry pathogenic variants in RARB and STRA6, which have been previously associated with this disorder. METHODS: We sequenced the exome of patients with unexplained PDAC syndrome and performed functional validation of candidate variants. RESULTS: We identified bi-allelic variants in WNT7B in fetuses with PDAC syndrome from two unrelated families. In one family, the fetus was homozygous for the c.292C>T (p.(Arg98*)) variant whereas the fetuses from the other family were compound heterozygous for the variants c.225C>G (p.(Tyr75*)) and c.562G>A (p.(Gly188Ser)). Finally, a molecular autopsy by proxy in a consanguineous couple that lost two babies due to lung hypoplasia revealed that both parents carry the p.(Arg98*) variant. Using a WNT signalling canonical luciferase assay, we demonstrated that the identified variants are deleterious. In addition, we found that wnt7bb mutant zebrafish display a defect of the swimbladder, an air-filled organ that is a structural homolog of the mammalian lung, suggesting that the function of WNT7B has been conserved during evolution for the development of these structures. CONCLUSION: Our findings indicate that defective WNT7B function underlies a form of lung hypoplasia that is associated with the PDAC syndrome, and provide evidence for involvement of the WNT-ß-catenin pathway in human lung, tracheal, ocular, cardiac, and renal development.

Management of copy number variants associated with incomplete penetrance and variable expressivity-Results of a French survey.

Increasing interest regarding neurodevelopmental disorders and democratization of chromosomal microarray analysis have led to growing identification of neuro-susceptibility copy number variations (CNVs). These CNVs have incomplete penetrance and variable expressivity (PIEV), which makes phenotypic features hard to predict. The French Consortium "AchroPuce" has provided a list of 17 CNVs that should be considered as PIEV CNVs. This list led to consensual French practices of healthcare professionals in postnatal diagnosis. However, no consensus was established in prenatal diagnosis and fetal pathology. 121 French health professionals were surveyed their opinions and practices regarding reporting of PIEV CNVs to patients, in order to identify key points so as to establish French recommendations. The survey showed that professionals in favor of reporting PIEV CNVs to patients in prenatal diagnosis and fetal pathology (respectively, 76% and 84% of respondents) considered highlighted that multidisciplinary consultation is the main point-of-care management before family survey. This statement is close to recommendations published worldwide. As a consequence, multidisciplinary expertise should be the basis of French recommendations concerning the reporting of PIEV CNVs and genetic counseling in prenatal diagnosis and fetal pathology.

Phenotypic spectrum and genomics of undiagnosed arthrogryposis multiplex congenita.

BACKGROUND: Arthrogryposis multiplex congenita (AMC) is characterised by congenital joint contractures in two or more body areas. AMC exhibits wide phenotypic and genetic heterogeneity. Our goals were to improve the genetic diagnosis rates of AMC, to evaluate the added value of whole exome sequencing (WES) compared with targeted exome sequencing (TES) and to identify new genes in 315 unrelated undiagnosed AMC families. METHODS: Several genomic approaches were used including genetic mapping of disease loci in multiplex or consanguineous families, TES then WES. Sanger sequencing was performed to identify or validate variants. RESULTS: We achieved disease gene identification in 52.7% of AMC index patients including nine recently identified genes (CNTNAP1, MAGEL2, ADGRG6, ADCY6, GLDN, LGI4, LMOD3, UNC50 and SCN1A). Moreover, we identified pathogenic variants in ASXL3 and STAC3 expanding the phenotypes associated with these genes. The most frequent cause of AMC was a primary involvement of skeletal muscle (40%) followed by brain (22%). The most frequent mode of inheritance is autosomal recessive (66.3% of patients). In sporadic patients born to non-consanguineous parents (n=60), de novo dominant autosomal or X linked variants were observed in 30 of them (50%). CONCLUSION: New genes recently identified in AMC represent 21% of causing genes in our cohort. A high proportion of de novo variants were observed indicating that this mechanism plays a prominent part in this developmental disease. Our data showed the added value of WES when compared with TES due to the larger clinical spectrum of some disease genes than initially described and the identification of novel genes.

Targeted next-generation sequencing in a large series of fetuses with severe renal diseases.

We report the screening of a large panel of genes in a series of 100 fetuses (98 families) affected with severe renal defects. Causative variants were identified in 22% of cases, greatly improving genetic counseling. The percentage of variants explaining the phenotype was different according to the type of phenotype. The highest diagnostic yield was found in cases affected with the ciliopathy-like phenotype (11/15 families and, in addition, a single heterozygous or a homozygous Class 3 variant in PKHD1 in three unrelated cases with autosomal recessive polycystic kidney disease). The lowest diagnostic yield was observed in cases with congenital anomalies of the kidney and urinary tract (9/78 families and, in addition, Class 3 variants in GREB1L in three unrelated cases with bilateral renal agenesis). Inheritance was autosomal recessive in nine genes (PKHD1, NPHP3, CEP290, TMEM67, DNAJB11, FRAS1, ACE, AGT, and AGTR1), and autosomal dominant in six genes (PKD1, PKD2, PAX2, EYA1, BICC1, and MYOCD). Finally, we developed an original approach of next-generation sequencing targeted RNA sequencing using the custom capture panel used for the sequencing of DNA, to validate one MYOCD heterozygous splicing variant identified in two male siblings with megabladder and inherited from their healthy mother.

Secretory phospholipase A2 expression and activity in preterm clinical chorioamnionitis with fetal involvement.

Secretory phospholipase A2 (sPLA2) regulates the first step of inflammatory cascade and is involved in several pathological processes. sPLA2 also plays a role in preterm labor and parturition, since they are triggered by inflammatory mediators such as prostaglandins. Interestingly, chorioamnionitis (i.e., the presence of intrauterine inflammation) is also often associated with preterm birth. We aimed to verify if chorioamnionitis with fetal involvement modifies sPLA2 activity and expression profile in mothers and neonates delivered prematurely. We collected maternal plasma and amniotic fluid, as well as bronchoalveolar lavage fluid from preterm neonates born to mothers with or without clinical chorioamnionitis with fetal involvement. We measured concentrations of sPLA2 subtype-IIA and -IB, total enzyme activity, and proteins. Urea ratio was used to obtain epithelial lining fluid concentrations. Enzyme activity measured in maternal plasma (P < 0.001) and amniotic fluid (P < 0.001) was higher in chorioamnionitis cases than in controls. This was mainly due to the increased production of sPLA2-IIA, as the subtype -IB was present in a smaller amount and was similar between the two groups; sPLA2-IIA was increased in epithelial lining fluid (P = 0.045) or increased, although without statistical significance, in maternal plasma (P = 0.06) and amniotic fluid (P = 0.08) of chorioamnionitis cases. Cytokines that are known to increase sPLA2-IIA expression (TNF-α and IL-1ß) or whose expression was increased by sPLA2-IIA (IL-8) were higher in histologically confirmed chorioamnionitis [TNF-α (P = 0.028), IL-1ß (P < 0.001), and IL-8 (P = 0.038)]. These data represent the basis for future studies on sPLA2-IIA inhibition to prevent deleterious consequences of chorioamnionitis and preterm birth.

Complex Compound Inheritance of Lethal Lung Developmental Disorders Due to Disruption of the TBX-FGF Pathway.

Primary defects in lung branching morphogenesis, resulting in neonatal lethal pulmonary hypoplasias, are incompletely understood. To elucidate the pathogenetics of human lung development, we studied a unique collection of samples obtained from deceased individuals with clinically and histopathologically diagnosed interstitial neonatal lung disorders: acinar dysplasia (n = 14), congenital alveolar dysplasia (n = 2), and other lethal lung hypoplasias (n = 10). We identified rare heterozygous copy-number variant deletions or single-nucleotide variants (SNVs) involving TBX4 (n = 8 and n = 2, respectively) or FGF10 (n = 2 and n = 2, respectively) in 16/26 (61%) individuals. In addition to TBX4, the overlapping ∼2 Mb recurrent and nonrecurrent deletions at 17q23.1q23.2 identified in seven individuals with lung hypoplasia also remove a lung-specific enhancer region. Individuals with coding variants involving either TBX4 or FGF10 also harbored at least one non-coding SNV in the predicted lung-specific enhancer region, which was absent in 13 control individuals with the overlapping deletions but without any structural lung anomalies. The occurrence of rare coding variants involving TBX4 or FGF10 with the putative hypomorphic non-coding SNVs implies a complex compound inheritance of these pulmonary hypoplasias. Moreover, they support the importance of TBX4-FGF10-FGFR2 epithelial-mesenchymal signaling in human lung organogenesis and help to explain the histopathological continuum observed in these rare lethal developmental disorders of the lung.

Discovering a new part of the phenotypic spectrum of Coffin-Siris syndrome in a fetal cohort.

PURPOSE: Genome-wide sequencing is increasingly being performed during pregnancy to identify the genetic cause of congenital anomalies. The interpretation of prenatally identified variants can be challenging and is hampered by our often limited knowledge of prenatal phenotypes. To better delineate the prenatal phenotype of Coffin-Siris syndrome (CSS), we collected clinical data from patients with a prenatal phenotype and a pathogenic variant in one of the CSS-associated genes. METHODS: Clinical data was collected through an extensive web-based survey. RESULTS: We included 44 patients with a variant in a CSS-associated gene and a prenatal phenotype; 9 of these patients have been reported before. Prenatal anomalies that were frequently observed in our cohort include hydrocephalus, agenesis of the corpus callosum, hypoplastic left heart syndrome, persistent left vena cava, diaphragmatic hernia, renal agenesis, and intrauterine growth restriction. Anal anomalies were frequently identified after birth in patients with ARID1A variants (6/14, 43%). Interestingly, pathogenic ARID1A variants were much more frequently identified in the current prenatal cohort (16/44, 36%) than in postnatal CSS cohorts (5%-9%). CONCLUSION: Our data shed new light on the prenatal phenotype of patients with pathogenic variants in CSS genes.

Broadening the phenotypic spectrum of TUBA1A tubulinopathy to syndromic arthrogryposis multiplex congenita.

The recent finding that some patients with fetal akinesia deformation sequence (FADS) carry variants in the TUBB2B gene has prompted us to add to the existing literature a first description of two fetal FADS cases carrying TUBA1A variants. Hitherto, only isolated cortical malformations have been described with TUBA1A mutation, including microlissencephaly, lissencephaly, central pachygyria and polymicrogyria-like cortical dysplasia, generalized polymicrogyria cortical dysplasia, and/or the "simplified" gyral pattern. The neuropathology of our fetal cases shows several common features of tubulinopathies, in particular, the dysmorphism of the basal ganglia, as the most pathognomonic sign. The cortical ribbon anomalies were extremely severe and concordant with the complex cortical malformation. In conclusion, we broaden the phenotypic spectrum of TUBA1A variants, to include FADS.

Prenatal Diagnosis of COL4A1 Mutations in Eight Cases: Further Delineation of the Neurohistopathological Phenotype.

BACKGROUND: Increasing number of mutations responsible for vascular lesions, leading to ischemic or hemorrhagic stroke in young adults, has been identified in the recent years. It has been demonstrated in both mice and humans, that mutations in COL4A1 gene promote cerebral hemorrhages. In humans, both adults and children may be affected, and the spectrum has been broadened recently to neonates and fetuses. METHODS: We present a cohort of eight COL4A1 mutated fetuses in which cerebral hemorrhages were detected by ultrasound leading to elective terminations of pregnancy. RESULTS: Our neuropathological studies demonstrated a strikingly similar pathological pattern, dominated by supra- and infratentorial multifocal hemorrhagic lesions of various abundance and age in the vicinity of enlarged small vessels having a discontinuous wall. This was constantly associated with a spectrum of supratentorial post-ischemic damages of the grey and white matters. Morphometric studies of brain vessels confirmed vascular dilation and hypervascularization in both grey and white matters and severe attenuation of the smooth-muscle actin staining in the white matter. CONCLUSION: These observations add to the rare human neuropathological phenotype of COL4A1 mutations. Its recognition is mandatory to enhance the number of tested patients in the future, as well as the genetic counseling of parents.

Copy number variations analysis in a cohort of 47 fetuses and newborns with congenital diaphragmatic hernia.

OBJECTIVES: The congenital diaphragmatic hernia (CDH), characterized by malformation of the diaphragm and lung hypoplasia, is a common and severe birth defect that affects around 1 in 4000 live births. However, the etiology of most cases of CDH remains unclear. The aim of this study was to perform a retrospective analysis of copy number variations (CNVs) using a high-resolution array comparative genomic hybridization (array-CGH) in a cohort of fetuses and newborns with CDH. METHODS: Forty seven fetuses and newborns with either isolated or syndromic CDH were analyzed by oligonucleotide-based array-CGH Agilent 180K technique. RESULTS: A mean of 10.2 CNVs was detected by proband with a total number of 480 CNVs identified based on five categories: benign, likely benign, of uncertain signification, likely pathogenic, and pathogenic. Diagnostic performance was estimated at 19.15% (i.e., likely pathogenic and pathogenic CNVs) for both CDH types. We identified 11 potential candidate genes: COL25A1, DSEL, EYA1, FLNA, MECOM, NRXN1, RARB, SPATA13, TJP2, XIRP2, and ZFPM2. CONCLUSION: We suggest that COL25A1, DSEL, EYA1, FLNA, MECOM, NRXN1, RARB, SPATA13, TJP2, XIRP2, and ZFPM2 genes may be related to CDH occurrence. Thus, this study provides a possibility for new methods of a positive diagnosis.

De novo mutations of SCN1A are responsible for arthrogryposis broadening the SCN1A-related phenotypes.

BACKGROUND: Arthrogryposis multiplex congenita (AMC) is the direct consequence of reduced fetal movements. AMC includes a large spectrum of diseases which result from variants in genes encoding components required for the formation or the function of the neuromuscular system. AMC may also result from central nervous involvement. SCN1A encodes Nav1.1, a critical component of voltage-dependent sodium channels which underlie action potential generation and propagation. Variants of SCN1A are known to be responsible for Dravet syndrome, a severe early-onset epileptic encephalopathy. We report pathogenic heterozygous missense de novo variants in SCN1A in three unrelated individuals with AMC. METHODS: Whole-exome sequencing was performed from DNA of the index case of AMC families. Heterozygous missense variants in SCN1A (p.Leu893Phe, p.Ala989Thr, p.Ile236Thr) were identified in three patients. Sanger sequencing confirmed the variants and showed that they occurred de novo. RESULTS: AMC was diagnosed from the second trimester of pregnancy in the three patients. One of them developed drug-resistant epileptic seizures from birth. We showed that SCN1A is expressed in both brain and spinal cord but not in skeletal muscle during human development. The lack of motor denervation as established by electromyographic studies or pathological examination of the spinal cord or skeletal muscle in the affected individuals suggests that AMC is caused by brain involvement. CONCLUSION: We show for the first time that SCN1A variants are responsible for early-onset motor defect leading to AMC indicating a critical role of SCN1A in prenatal motor development and broadening the phenotypic spectrum of variants in SCN1A.

Loss-of-function mutations in KIF14 cause severe microcephaly and kidney development defects in humans and zebrafish.

Mutations in KIF14 have previously been associated with either severe, isolated or syndromic microcephaly with renal hypodysplasia (RHD). Syndromic microcephaly-RHD was strongly reminiscent of clinical ciliopathies, relating to defects of the primary cilium, a signalling organelle present on the surface of many quiescent cells. KIF14 encodes a mitotic kinesin, which plays a key role at the midbody during cytokinesis and has not previously been shown to be involved in cilia-related functions. Here, we analysed four families with fetuses presenting with the syndromic form and harbouring biallelic variants in KIF14. Our functional analyses showed that the identified variants severely impact the activity of KIF14 and likely correspond to loss-of-function mutations. Analysis in human fetal tissues further revealed the accumulation of KIF14-positive midbody remnants in the lumen of ureteric bud tips indicating a shared function of KIF14 during brain and kidney development. Subsequently, analysis of a kif14 mutant zebrafish line showed a conserved role for this mitotic kinesin. Interestingly, ciliopathy-associated phenotypes were also present in mutant embryos, supporting a potential direct or indirect role for KIF14 at cilia. However, our in vitro and in vivo analyses did not provide evidence of a direct role for KIF14 in ciliogenesis and suggested that loss of kif14 causes ciliopathy-like phenotypes through an accumulation of mitotic cells in ciliated tissues. Altogether, our results demonstrate that KIF14 mutations result in a severe syndrome associating microcephaly and RHD through its conserved function in cytokinesis during kidney and brain development.

A retrospective study on the efficacy of prenatal diagnosis for pregnancies at risk of mitochondrial DNA disorders.

PURPOSE: Prenatal diagnosis of mitochondrial DNA (mtDNA) disorders is challenging due to potential instability of fetal mutant loads and paucity of data connecting prenatal mutant loads to postnatal observations. Retrospective study of our prenatal cohort aims to examine the efficacy of prenatal diagnosis to improve counseling and reproductive options for those with pregnancies at risk of mtDNA disorders. METHODS: We report on a retrospective review of 20 years of prenatal diagnosis of pathogenic mtDNA variants in 80 pregnant women and 120 fetuses. RESULTS: Patients with undetectable pathogenic variants (n = 29) consistently had fetuses free of variants, while heteroplasmic women (n = 51) were very likely to transmit their variant (57/78 fetuses, 73%). In the latter case, 26 pregnancies were terminated because fetal mutant loads were >40%. Of the 84 children born, 27 were heteroplasmic (mutant load <65%). To date, no medical problems related to mitochondrial dysfunction have been reported. CONCLUSION: Placental heterogeneity of mutant loads questioned the reliability of chorionic villous testing. Fetal mutant load stability, however, suggests the reliability of a single analysis of amniotic fluid at any stage of pregnancy for prenatal diagnosis of mtDNA disorders. Mutant loads under 40% reliably predict lack of symptoms in the progeny of heteroplasmic women.

Early prenatal diagnosis of alveolar capillary dysplasia with misalignment of pulmonary veins due to a 16q24.1 deletion.

First trimester ultrasound screening is an essential fetal examination performed generally at 11-13 weeks of gestation (WG). However, it does not allow for an accurate description of all fetal organs, partly due to their development in progress. Meanwhile, increased nuchal translucency (INT) is a widely used marker known to be associated with chromosomal deleterious rearrangements. We report on a 14 WG fetus with an association of INT and univentricular congenital heart malformation (CHM) leading to chorionic villous sampling (CVS). Cytogenetic investigations performed using array-Comparative Genomic Hybridization (CGH) and fluorescence in situ hybridization (FISH) demonstrated a 1.17 Mb deletion in 16q24.1 encompassing FOXF1 arisen de novo on maternal inherited chromosome. Fetopathological study confirmed CHM with hypoplastic left heart syndrome (HLHS) associating aortic atresia, mitral stenosis, and left ventricular hypoplasia and revealed in addition specific lung lesions corresponding to alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV). This is so far the first case of first trimester prenatal diagnosis of ACDMPV due to the deletion of FOXF1 gene. An interpretation of the complex genomic data generated by ultrasound markers is facilitated considerably by the genotype-phenotype correlations on fetopathological examination.