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.
Key points
What is already known about this topic?
Biallelic PHGDH variants are associated with serine‐deficiency disorders and Neu Laxova syndrome (NLS).
NLS is characterized by severe IUGR, ichthyosis, abnormal facial features, limb abnormalities with arthrogryposis and a wide spectrum of severe malformations of the CNS.
NLS is usually suggested in the third trimester of pregnancy or in the neonatal period.
What does this study add?
The study reports early and severe presentation of NLS with increased nuchal translucency and megacystis.
Our findings suggest that megacystis is secondary to a neurogenic muscular atrophy, extending neuromuscular findings reported in NLS.
The study highlights the intrafamilial variability of NLS.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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. It resulted in three clusters showing phenotypes of different severities. While no clear genotype–phenotype correlation appeared within the first two clusters, a single patient was outlying the cohort data (cluster 3) with the most atypical phenotype and the most distal frameshift variant in the gene. We added two other patients with similar distal pathogenic variants and observed a tendency toward mild and/or atypical phenotypes. We hypothesized that this finding could potentially be related to escaping nonsense mediated RNA decay, but found no evidence of such decay in vivo for any of the CHD7 pathogenic variation tested. This indicates that this milder phenotype may rather result from the production of a protein retaining all functional domains.
Unsupervised machine learning and clustering in patients with CHARGE syndrome revealed a tendency towards mild/atypical phenotypes due to very distal CHD7 variants. RNA studies detected bi‐allelic expression whatever the location of the variant, indicating absence of NMD.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Pathogenic variants in the core spliceosome U5 small nuclear ribonucleoprotein gene EFTUD2/SNU114 cause the craniofacial disorder mandibulofacial dysostosis Guion‐Almeida type (MFDGA). ...MFDGA‐associated variants in EFTUD2 comprise large deletions encompassing EFTUD2, intragenic deletions and single nucleotide truncating or missense variants. These variants are predicted to result in haploinsufficiency by loss‐of‐function of the variant allele. While the contribution of deletions within EFTUD2 to allele loss‐of‐function are self‐evident, the mechanisms by which missense variants are disease‐causing have not been characterized functionally. Combining bioinformatics software prediction, yeast functional growth assays, and a minigene (MG) splicing assay, we have characterized how MFDGA missense variants result in EFTUD2 loss‐of‐function. Only four of 19 assessed missense variants cause EFTUD2 loss‐of‐function through altered protein function when modeled in yeast. Of the remaining 15 missense variants, five altered the normal splicing pattern of EFTUD2 pre‐messenger RNA predominantly through exon skipping or cryptic splice site activation, leading to the introduction of a premature termination codon. Comparison of bioinformatic predictors for each missense variant revealed a disparity amongst different software packages and, in many cases, an inability to correctly predict changes in splicing subsequently determined by MG interrogation. This study highlights the need for laboratory‐based validation of bioinformatic predictions for EFTUD2 missense variants.
We have carried out a functional analysis of missense variants in EFTUD2 associated with mandibulofacial dysostosis Guion‐Almeida type. Using a combination of bioinformatics software prediction, yeast functional growth assays and a minigene splicing assay, we have characterised how missense variants result in EFTUD2 loss‐of‐function. We find that EFTUD2 missense variants not only affect protein function but also splicing of the EFTUD2 pre‐messenger RNA that is not predicted well by currently available bioinformatics programs.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Cardiomyopathies are diseases of the heart muscle with variable clinical expressivity. Most of forms are inherited as dominant trait, and with incomplete penetrance until adulthood. Severe forms of ...cardiomyopathies were observed during the antenatal period with a pejorative issue leading to fetal death or medical interruption of pregnancy. Variable phenotypes and genetic heterogeneity make etiologic diagnosis difficult. We report 11 families (16 cases) whose unborn, newborn or infant with early onset cardiomyopathies. Detailed morphological and histological examinations of hearts were implemented, as well as genetic analysis on a cardiac targeted NGS panel. This strategy allowed the identification of the genetic cause of the cardiomyopathy in 8/11 families. Compound heterozygous mutations in dominant adulthood cardiomyopathy genes were found in two, pathogenic variants in co‐dominant genes in one, de novo mutations in 5 including a germline mosaicism in one family. Parental testing was systematically performed to detect mutation carriers, and to manage cardiological surveillance and propose a genetic counseling. This study highlights the great diagnostic value of the genetic testing of severe antenatal cardiomyopathy both for genetic counseling and to detect presymptomatic parents at higher risk of developing cardiomyopathy.
Fetal cardiomyopathies are rare and could led to in utero fetal death or termination of pregnancy. Morphological analysis of 16 cases allowed to described their characteristics. Genetic analysis on a panel of cardiomyopathy genes has attested of a genetic origin of these cases and also highlighted a particular pattern (high rate of de novo mutation, compound heterozygous and co‐dominance) participating to the explanation of a severe cardiomyopathy. This work confirmed the interest of genetic testing of fetal cardiomyopathies to improve genetic counselling in the families.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Objectives
The antenatal phenotypic spectrum of Noonan Syndrome (NS) requires better characterization.
Methods
This multicenter retrospective observational included 16 fetuses with molecularly ...confirmed NS admitted for fetopathological examination between 2009 and 2016.
Results
Among 12 pathogenic variants (PV) in PTPN11 (80%), 5 (42%) fell between position c.179 and c.182. Ultrasound showed increased nuchal translucency (n = 13/16, 93%), increased nuchal fold after 15 weeks of gestation (n = 12/16, 75%), pleural effusions (n = 11/16, 69%), polyhydramnios (n = 9/16, 56%), hydrops (n = 7/16, 44%), cardiovascular (n = 6/16, 38%) and cerebral (n = 4/16, 25%) anomalies. Fetopathological examination found dysmorphic features in all cases, cardiovascular anomalies (n = 12/15, 80%), pulmonary hypoplasia (n = 10/15, 67%), effusions (n = 7/15, 47%) and neuropathological anomalies (n = 5/15, 33%). Hydrops was significantly (p = 0.02) more frequent in the four fetuses with RIT1, NRAS and RAF1 PV versus the 12 fetuses with PTPN11 PV.
Conclusions
Increased nuchal translucency and nuchal fold is common in NS. Noonan Syndrome antenatal phenotype showed high in utero fetal death, hydrops, prenatal pleural effusion and pulmonary hypoplasia, although the inclusion of only deceased fetuses will have selected more severe phenotypes. Non‐specific cardiovascular and neurological abnormalities should be added to NS antenatal phenotype. Next generation sequencing will help detect more genotypes, clarifying the prenatal phenotype and identifying genotype‐phenotype correlations.
Key points
What's already known about this topic?
Noonan Syndrome (NS) is an autosomal dominant disorder with highly variable antenatal phenotype, which sometimes does not correlate with the severity of the postnatal phenotype, making counseling challenging.
The ultrasound phenotype of NS is associated with increased nuchal translucency in first trimester and beyond the second trimester of pregnancy, polyhydramnios, pleural effusion, ascites, edema and cardiac and facial anomalies.
These signs are frequent and non‐specific.
What does this study add?
This case series better characterizes fetuses carrying NS, identifying a wider phenotypic spectrum than originally reported. The antenatal phenotype includes non‐specific cardiovascular, renal and neurological abnormalities.
This phenotype seems to be more severe than previously thought, with a high rate of hydrops, prenatal pleural effusion and pulmonary hypoplasia.
Different genotypes have specific phenotypes, for example, hydrops was more associated to mutations in non‐PTPN11 targets.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Congenital combined vitamin K‐dependent clotting factors deficiency (VKCFD) is a rare autosomal recessive disease resulting in hemorrhagic symptoms usually associated with developmental disorders and ...bone abnormalities. Pathogenic variants in two genes encoding enzymes of the vitamin K cycle, GGCX and VKORC1, can lead to this disorder. We present the case of a male fetus with a brachytelephalangic chondrodysplasia punctata (CDP), absence of nasal bone, growth restriction, and bilateral ventriculomegaly at 18 weeks of gestation. Pathological examination showed a Binder phenotype, hypoplastic distal phalanges, stippled epiphyses, and brain abnormalities suggestive of a brain hemorrhage. Two GGCX pathogenic variants inherited respectively from the mother and the father were identified. To our knowledge, this is the first prenatal description of VKCFD. Even if it remains a rare etiology, which is mostly described in children or adult patients, VKCFD should be considered in fetuses with CDP.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Background
The recent outbreak of Zika virus (ZIKV) infection and the associated increased prevalence of microcephaly in Brazil underline the impact of viral infections on embryo fetal development. ...The aim of the present study is to provide a detailed clinical and histopathological study of the fetal disruption caused by the ZIKV, with a special focus on the associated neuropathological findings.
Methods
A detailed feto‐placental examination, as well as neuropathological and neurobiological studies were performed on three fetuses collected after pregnancy termination between 22 and 25 weeks of gestation (WG), because brain malformations associated with a maternal and fetal ZIKV infection was diagnosed.
Results
In all three cases, the maternal infection occurred during the first trimester of pregnancy. A small head was observed on the ultrasound examination of the second trimester of pregnancy and led to the diagnosis of ZIKV fetopathy and pregnancy termination. The fetal histopathological examination was unremarkable on the viscera but showed on the testis an interstitial lymphocytic infiltrate. The placenta contained a Hofbauer cells hyperplasia with signs of inflammation. Neuropathological findings included a meningoencephalitis and an ex vacuo hydrocephalus. Immunohistochemical studies showed the presence of T lymphocytic and histiocytic meningitis associated with an abundant cerebral astroglial and macrophagic reaction. In situ hybridization demonstrated, abundant ZIKV particles within the cerebral parenchyma mainly in the ventricular/subventricular zone and in the cortical plate. In addition massive cells death and endoplasmic reticulum damage were present.
Conclusion
The present study reports on the clinical and histopathological findings observed in three fetuses infected by the ZIKV. It emphasizes the severity of brain damages and the minimal visceral and placental changes observed upon ZIKV infection. This confirms the selective neurotropism of ZIKV. Finally, it allows us to describe the cascade of multifactorial developmental defects leading to microcephaly.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Developmental abnormalities provide a unique opportunity to seek for the molecular mechanisms underlying human organogenesis. Esophageal development remains incompletely understood and elucidating ...causes for esophageal atresia (EA) in humans would contribute to achieve a better comprehension. Prenatal detection, syndromic classification, molecular diagnosis, and prognostic factors in EA are challenging. Some syndromes have been described to frequently include EA, such as CHARGE, EFTUD2‐mandibulofacial dysostosis, Feingold syndrome, trisomy 18, and Fanconi anemia. However, no molecular diagnosis is made in most cases, including frequent associations, such as Vertebral‐Anal‐Cardiac‐Tracheo‐Esophageal‐Renal‐Limb defects (VACTERL). This study evaluates the clinical and genetic test results of 139 neonates and 9 fetuses followed‐up at the Necker‐Enfants Malades Hospital over a 10‐years period. Overall, 52 cases were isolated EA (35%), and 96 were associated with other anomalies (65%). The latter group is divided into three subgroups: EA with a known genomic cause (9/148, 6%); EA with Vertebral‐Anal‐Cardiac‐Tracheo‐Esophageal‐Renal‐Limb defects (VACTERL) or VACTERL/Oculo‐Auriculo‐Vertebral Dysplasia (VACTERL/OAV) (22/148, 14%); EA with associated malformations including congenital heart defects, duodenal atresia, and diaphragmatic hernia without known associations or syndromes yet described (65/148, 44%). Altogether, the molecular diagnostic rate remains very low and may underlie frequent non‐Mendelian genetic models.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
CHARGE syndrome is a multiple anomaly disorder in which patients present with a variety of phenotypes, including ocular coloboma, heart defects, choanal atresia, retarded growth and development, ...genitourinary hypoplasia and ear abnormalities. Despite 70-90% of CHARGE syndrome cases resulting from mutations in the gene CHD7, which encodes an ATP-dependent chromatin remodeller, the pathways underlying the diverse phenotypes remain poorly understood. Surprisingly, our studies of a knock-in mutant mouse strain that expresses a stabilized and transcriptionally dead variant of the tumour-suppressor protein p53 (p53(25,26,53,54)), along with a wild-type allele of p53 (also known as Trp53), revealed late-gestational embryonic lethality associated with a host of phenotypes that are characteristic of CHARGE syndrome, including coloboma, inner and outer ear malformations, heart outflow tract defects and craniofacial defects. We found that the p53(25,26,53,54) mutant protein stabilized and hyperactivated wild-type p53, which then inappropriately induced its target genes and triggered cell-cycle arrest or apoptosis during development. Importantly, these phenotypes were only observed with a wild-type p53 allele, as p53(25,26,53,54)(/-) embryos were fully viable. Furthermore, we found that CHD7 can bind to the p53 promoter, thereby negatively regulating p53 expression, and that CHD7 loss in mouse neural crest cells or samples from patients with CHARGE syndrome results in p53 activation. Strikingly, we found that p53 heterozygosity partially rescued the phenotypes in Chd7-null mouse embryos, demonstrating that p53 contributes to the phenotypes that result from CHD7 loss. Thus, inappropriate p53 activation during development can promote CHARGE phenotypes, supporting the idea that p53 has a critical role in developmental syndromes and providing important insight into the mechanisms underlying CHARGE syndrome.
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DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The NADSYN1 gene MIM*608285 encodes the NAD synthetase 1 enzyme involved in the final step of NAD biosynthesis, crucial for cell metabolism and organ embryogenesis. Perturbating the role of NAD ...biosynthesis results in the association of vertebral, cardiac, renal, and limb anomalies (VCRL). This condition was initially characterized as severe with perinatal lethality or developmental delay and complex malformations in alive cases. Sixteen NADSYN1‐associated patients have been published so far. This study illustrates the wide phenotypic variability in NADSYN1‐associated NAD deficiency disorder. We report the clinical and molecular findings in three novel cases, two of them being siblings with the same homozygous variant and presenting with either a very severe prenatal lethal or a mild phenotypic form. In addition to an exhaustive literature, we validate the expansion of the spectrum of NAD deficiency disorder. Our findings indicate that NAD deficiency disorder should be suspected not only in the presence of the full spectrum of VCRL, but even a single of the aforementioned organs is affected. Decreased plasmatic levels of NAD should then strongly encourage the screening for any of the genes responsible for a NAD deficiency disorder.
Clinicians should suspect NAD deficiency disorder when a patient presents with congenital malformations, especially when vertebral, cardiac, renal, or limb defects are present.
We expanded NAD deficiency disorder spectrum with the presentation of three cases from two unrelated families, with high inter‐ and intra‐familial variability.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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