Biallelic pathogenic variants in roundabout guidance receptor 1 associate with syndromic congenital anomalies of the kidney and urinary tract.

Congenital anomalies of the kidney and urinary tract (CAKUT) represent the most common cause of chronic kidney failure in children. Despite growing knowledge of the genetic causes of CAKUT, the majority of cases remain etiologically unsolved. Genetic alterations in roundabout guidance receptor 1 (ROBO1) have been associated with neuronal and cardiac developmental defects in living individuals. Although Slit-Robo signaling is pivotal for kidney development, diagnostic ROBO1 variants have not been reported in viable CAKUT to date. By next-generation-sequencing methods, we identified six unrelated individuals and two non-viable fetuses with biallelic truncating or combined missense and truncating variants in ROBO1. Kidney and genitourinary manifestation included unilateral or bilateral kidney agenesis, vesicoureteral junction obstruction, vesicoureteral reflux, posterior urethral valve, genital malformation, and increased kidney echogenicity. Further clinical characteristics were remarkably heterogeneous, including neurodevelopmental defects, intellectual impairment, cerebral malformations, eye anomalies, and cardiac defects. By in silico analysis, we determined the functional significance of identified missense variants and observed absence of kidney ROBO1 expression in both human and murine mutant tissues. While its expression in multiple tissues may explain heterogeneous organ involvement, variability of the kidney disease suggests gene dosage effects due to a combination of null alleles with mild hypomorphic alleles. Thus, comprehensive genetic analysis in CAKUT should include ROBO1 as a new cause of recessively inherited disease. Hence, in patients with already established ROBO1-associated cardiac or neuronal disorders, screening for kidney involvement is indicated.

p57-discordant villi in hydropic products of conception: a clinicopathological study of 70 cases.

p57 immunostaining is performed on hydropic products of conception to diagnose hydatidiform moles (HMs), which can progress to gestational trophoblastic neoplasia. Partial hydatidiform mole (PHM) and hydropic abortion (HA) display positive staining in stromal and cytotrophoblastic cells, whereas complete hydatidiform mole (CHM) is characterized by loss of p57 expression in both cell types. In some cases, an aberrant pattern is observed, called discordant p57 expression, with positive cytotrophoblast staining and negative stromal staining, or vice versa. The aim of this study was to describe the clinical, biological, and pathological characteristics of p57-discordant villi (p57DV) and other associated populations in cases of divergent p57 expression and to compare the evolutions of p57DV-associated and classic CHMs. Seventy cases of p57DV diagnosed by referent pathologists were divided into two groups, G1: p57DV ± non-CHM component (n = 22) and G2: p57DV + CHM component (n = 48). p57DV morphology was similar in the two groups. Observation of more than two populations and hybrid villi on p57 immunostaining were significantly more frequent in G2. The clinical, ultrasound, and biological presentations of p57DV-associated and classic CHMs were similar. The initial pathological diagnosis was more frequently incorrect, missing the CHM component, for the p57DV-associated CHMs. Molecular genotyping was informative in seven cases and identified as androgenetic/biparental mosaicism in four cases. These results show that p57DV are a diagnostic challenge for pathologists and that most are associated with a CHM component. However, the clinical management of p57DV-associated CHMs should be the same as that of classic CHMs.

TAR syndrome: Clinical and molecular characterization of a cohort of 26 patients and description of novel noncoding variants of RBM8A.

Thrombocytopenia-absent radius (TAR) syndrome is characterized by radial defect and neonatal thrombocytopenia. It is caused by biallelic variants of RBM8A gene (1q21.1) with the association of a null allele and a hypomorphic noncoding variant. RBM8A encodes Y14, a core protein of the exon junction complex involved in messenger RNA maturation. To date, only two hypomorphic variants have been identified. We report on a cohort of 26 patients affected with TAR syndrome and carrying biallelic variants in RBM8A. Half patients carried a 1q21.1 deletion and one of the two known hypomorphic variants. Four novel noncoding variants of RBM8A were identified in the remaining patients. We developed experimental models enabling their functional characterization in vitro. Two variants, located respectively in the 5'-untranslated region (5'-UTR) and 3'-UTR regions, are responsible for a diminished expression whereas two intronic variants alter splicing. Our results bring new insights into the molecular knowledge of TAR syndrome and enabled us to propose genetic counseling for patients' families.

Bardet-Biedl syndrome: Antenatal presentation of forty-five fetuses with biallelic pathogenic variants in known Bardet-Biedl syndrome genes.

Bardet-Biedl syndrome (BBS) is an emblematic ciliopathy associated with retinal dystrophy, obesity, postaxial polydactyly, learning disabilities, hypogonadism and renal dysfunction. Before birth, enlarged/cystic kidneys as well as polydactyly are the hallmark signs of BBS to consider in absence of familial history. However, these findings are not specific to BBS, raising the problem of differential diagnoses and prognosis. Molecular diagnosis during pregnancies remains a timely challenge for this heterogeneous disease (22 known genes). We report here the largest cohort of BBS fetuses to better characterize the antenatal presentation. Prenatal ultrasound (US) and/or autopsy data from 74 fetuses with putative BBS diagnosis were collected out of which molecular diagnosis was established in 51 cases, mainly in BBS genes (45 cases) following the classical gene distribution, but also in other ciliopathy genes (6 cases). Based on this, an updated diagnostic decision tree is proposed. No genotype/phenotype correlation could be established but postaxial polydactyly (82%) and renal cysts (78%) were the most prevalent symptoms. However, autopsy revealed polydactyly that was missed by prenatal US in 55% of the cases. Polydactyly must be carefully looked for in pregnancies with apparently isolated renal anomalies in fetuses.

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.

Novel mutations in the ciliopathy-associated gene CPLANE1 (C5orf42) cause OFD syndrome type VI rather than Joubert syndrome.

Mutations in CPLANE1 (previously known as C5orf42) cause Oral-Facial-Digital Syndrome type VI (OFD6) as well as milder Joubert syndrome (JS) phenotypes. Seven new cases from five unrelated families diagnosed with pure OFD6 were systematically examined. Based on the clinical manifestations of these patients and those described in the literature, we revised the diagnostic features of OFD6 and include the seven most common characteristics: 1) molar tooth sign, 2) tongue hamartoma and/or lobulated tongue, 3) additional frenula, 4) mesoaxial polydactyly of hands, 5) preaxial polydactyly of feet, 6) syndactyly and/or bifid toe, and 7) hypothalamic hamartoma. By whole or targeted exome sequencing, we identified seven novel germline recessive mutations in CPLANE1, including missense, nonsense, frameshift and canonical splice site variants, all causing OFD6 in these patients. Since CPLANE1 is also mutated in JS patients, we examined whether a genotype-phenotype correlation could be established. We gathered and compared 46 biallelic CPLANE1 mutations reported in 32 JS and 26 OFD6 patients. Since no clear correlation between paired genotypes and clinical outcomes could be determined, we concluded that patient's genetic background and gene modifiers may modify the penetrance and expressivity of CPLANE1 causal alleles. To conclude, our study provides a comprehensive view of the phenotypic range, the genetic basis and genotype-phenotype association in OFD6 and JS. The updated phenotype scoring system together with the identification of new CPLANE1 mutations will help clinicians and geneticists reach a more accurate diagnosis for JS-related disorders.

Histologic Chorioamnionitis and Bronchopulmonary Dysplasia in Preterm Infants: The Epidemiologic Study on Low Gestational Ages 2 Cohort.

OBJECTIVE: To investigate the association between histologic chorioamnionitis (HCA) and bronchopulmonary dysplasia (BPD) in very preterm infants, both in a general population and for those born after spontaneous preterm labor and after preterm premature rupture of membranes (pPROM). STUDY DESIGN: This study included 2513 live born singletons delivered at 24-31 weeks of gestation from a national prospective population-based cohort of preterm births; 1731 placenta reports were available. HCA was defined as neutrophil infiltrates in the amnion, chorion of the membranes, or chorionic plate, associated or not with funisitis. The main outcome measure was moderate or severe BPD. Analyses involved logistic regressions and multiple imputation for missing data. RESULTS: The incidence of HCA was 28.4% overall: 38% in cases of preterm labor, 64% in cases of pPROM, and less than 5% in cases of vascular disorders. Overall, the risk of BPD after adjustment for gestational age, sex, and antenatal steroids was reduced for infants with HCA (HCA alone: aOR 0.6 [95% CI 0.4-0.9]; associated with funisitis: aOR 0.5 [95% CI 0.3-0.8]). This finding was explained by the high rate of BPD and low rate of chorioamnionitis among children with fetal growth restriction. HCA was not associated with BPD in the preterm labor (13.4% vs 8.5%; aOR 0.9; 95% CI 0.5-1.8) or in the pPROM group (12.9% vs 12.1%; aOR 0.6; 95% CI 0.3-1.3). CONCLUSION: In homogeneous groups of infants born after preterm labor or pPROM, HCA is not associated with BPD.

SALL4 expression in gestational trophoblastic tumors: a useful tool to distinguish choriocarcinoma from placental site trophoblastic tumor and epithelioid trophoblastic tumor.

SALL4 has important functions in embryonic stem cells. The aim of this study was to investigate SALL4 expression in gestational trophoblastic neoplasia. We hypothesized that it could help to distinguish choriocarcinoma, the presumed most primitive form of gestational trophoblastic neoplasia, from placental site trophoblastic tumor and epithelioid trophoblastic tumor, which would be more differentiated variants. This study included 31 gestational trophoblastic neoplasias: 19 choriocarcinomas, 9 placental site trophoblastic tumors, 1 epithelioid trophoblastic tumor, and 2 mixed tumors comprising a placental site trophoblastic tumor and an epithelioid trophoblastic tumor. Unlike usual markers of gestational trophoblastic neoplasia (p63, human chorionic gonadotrophin and human placental lactogen), SALL4 was expressed in 100% of choriocarcinomas and it was not detected in any placental site trophoblastic tumor and epithelioid trophoblastic tumor. However, the proportion of positive cells varied in a wide range, from 10% to 70%, reflecting the fact that SALL4 was specifically present in mononuclear cells consistent with neoplastic cytotrophoblast. So, SALL4 may be helpful in the differential diagnosis of gestational trophoblastic neoplasias.

Novel NEK8 Mutations Cause Severe Syndromic Renal Cystic Dysplasia through YAP Dysregulation.

Ciliopathies are a group of genetic multi-systemic disorders related to dysfunction of the primary cilium, a sensory organelle present at the cell surface that regulates key signaling pathways during development and tissue homeostasis. In order to identify novel genes whose mutations would cause severe developmental ciliopathies, >500 patients/fetuses were analyzed by a targeted high throughput sequencing approach allowing exome sequencing of >1200 ciliary genes. NEK8/NPHP9 mutations were identified in five cases with severe overlapping phenotypes including renal cystic dysplasia/hypodysplasia, situs inversus, cardiopathy with hypertrophic septum and bile duct paucity. These cases highlight a genotype-phenotype correlation, with missense and nonsense mutations associated with hypodysplasia and enlarged cystic organs, respectively. Functional analyses of NEK8 mutations in patient fibroblasts and mIMCD3 cells showed that these mutations differentially affect ciliogenesis, proliferation/apoptosis/DNA damage response, as well as epithelial morphogenesis. Notably, missense mutations exacerbated some of the defects due to NEK8 loss of function, highlighting their likely gain-of-function effect. We also showed that NEK8 missense and loss-of-function mutations differentially affect the regulation of the main Hippo signaling effector, YAP, as well as the expression of its target genes in patient fibroblasts and renal cells. YAP imbalance was also observed in enlarged spheroids of Nek8-invalidated renal epithelial cells grown in 3D culture, as well as in cystic kidneys of Jck mice. Moreover, co-injection of nek8 MO with WT or mutated NEK8-GFP RNA in zebrafish embryos led to shortened dorsally curved body axis, similar to embryos injected with human YAP RNA. Finally, treatment with Verteporfin, an inhibitor of YAP transcriptional activity, partially rescued the 3D spheroid defects of Nek8-invalidated cells and the abnormalities of NEK8-overexpressing zebrafish embryos. Altogether, our study demonstrates that NEK8 human mutations cause major organ developmental defects due to altered ciliogenesis and cell differentiation/proliferation through deregulation of the Hippo pathway.

[Cardiac fibroma: A rare cause of sudden child death]. / Le fibrome cardiaque : une cause rare de mort subite de l'enfant.

We report the case of a 3-year-old child who died from the consequences of a cardio-respiratory arrest despite reanimation procedures. Echocardiography and magnetic resonance imaging (MRI) revealed a mass of the free wall of the left ventricle. Autopsy confirmed the existence of a solitary myocardial tumor, well-circumscribed, firm, with a whitish and trabeculated cut surface. Histologically, the tumor consisted of bundles of spindle-shaped and regular cells mingling with collagen and elastic fibers, insinuating themselves between myocytes in periphery. Calcifications were present. After immunohistochemistry, the cells were highlighted by anti-actin smooth muscle antibody; but they were not highlighted by anti-desmin, anti-ß catenin and anti-Ki67 antibodies. The diagnosis of cardiac fibroma was made. The primary cardiac tumors of child are rare and usually benign. They are essentially represented by rhabdomyoma and fibroma. Cardiac fibroma mostly occurs during the first year of life. It can be revealed by cardiac insufficiency, arrhythmia, chest pain or sudden death.

New insights into genotype-phenotype correlation for GLI3 mutations.

The phenotypic spectrum of GLI3 mutations includes autosomal dominant Greig cephalopolysyndactyly syndrome (GCPS) and Pallister-Hall syndrome (PHS). PHS was first described as a lethal condition associating hypothalamic hamartoma, postaxial or central polydactyly, anal atresia and bifid epiglottis. Typical GCPS combines polysyndactyly of hands and feet and craniofacial features. Genotype-phenotype correlations have been found both for the location and the nature of GLI3 mutations, highlighting the bifunctional nature of GLI3 during development. Here we report on the molecular and clinical study of 76 cases from 55 families with either a GLI3 mutation (49 GCPS and 21 PHS), or a large deletion encompassing the GLI3 gene (6 GCPS cases). Most of mutations are novel and consistent with the previously reported genotype-phenotype correlation. Our results also show a correlation between the location of the mutation and abnormal corpus callosum observed in some patients with GCPS. Fetal PHS observations emphasize on the possible lethality of GLI3 mutations and extend the phenotypic spectrum of malformations such as agnathia and reductional limbs defects. GLI3 expression studied by in situ hybridization during human development confirms its early expression in target tissues.

C5orf42 is the major gene responsible for OFD syndrome type VI.

Oral-facial-digital syndrome type VI (OFD VI) is a recessive ciliopathy defined by two diagnostic criteria: molar tooth sign (MTS) and one or more of the following: (1) tongue hamartoma (s) and/or additional frenula and/or upper lip notch; (2) mesoaxial polydactyly of one or more hands or feet; (3) hypothalamic hamartoma. Because of the MTS, OFD VI belongs to the "Joubert syndrome related disorders". Its genetic aetiology remains largely unknown although mutations in the TMEM216 gene, responsible for Joubert (JBS2) and Meckel-Gruber (MKS2) syndromes, have been reported in two OFD VI patients. To explore the molecular cause(s) of OFD VI syndrome, we used an exome sequencing strategy in six unrelated families followed by Sanger sequencing. We identified a total of 14 novel mutations in the C5orf42 gene in 9/11 families with positive OFD VI diagnostic criteria including a severe fetal case with microphthalmia, cerebellar hypoplasia, corpus callosum agenesis, polydactyly and skeletal dysplasia. C5orf42 mutations have already been reported in Joubert syndrome confirming that OFD VI and JBS are allelic disorders, thus enhancing our knowledge of the complex, highly heterogeneous nature of ciliopathies.

SALL4 is a marker of the embryonal subtype of hepatoblastoma.

AIMS: SALL4 is a marker of germ cell tumours. The aim of this study was to investigate SALL4 expression in blastemal tumours, particularly in hepatoblastoma. METHODS AND RESULTS: The study included 12 hepatoblastomas. Eight hepatoblastomas were pure epithelial tumours, and four were mixed epithelial and mesenchymal tumours. The patients were nine males and three females with a mean age of 14.6 months. Immunohistochemistry was performed with an antibody against SALL4, using an automated immunostainer. Seven of 12 hepatoblastomas showed nuclear staining only in the embryonal component. Fetal and mesenchymal components were negative. CONCLUSIONS: SALL4 is expressed in blastemal tumours, particularly in the embryonal subtype of hepatoblastoma. Pathologists need to be aware of such expression so that misdiagnosis can be avoided.

Identification of mutations in TMEM5 and ISPD as a cause of severe cobblestone lissencephaly.

Cobblestone lissencephaly is a peculiar brain malformation with characteristic radiological anomalies. It is defined as cortical dysplasia that results when neuroglial overmigration into the arachnoid space forms an extracortical layer that produces agyria and/or a "cobblestone" brain surface and ventricular enlargement. Cobblestone lissencephaly is pathognomonic of a continuum of autosomal-recessive diseases characterized by cerebral, ocular, and muscular deficits. These include Walker-Warburg syndrome, muscle-eye-brain disease, and Fukuyama muscular dystrophy. Mutations in POMT1, POMT2, POMGNT1, LARGE, FKTN, and FKRP identified these diseases as alpha-dystroglycanopathies. Our exhaustive screening of these six genes, in a cohort of 90 fetal cases, led to the identification of a mutation in only 53% of the families, suggesting that other genes might also be involved. We therefore decided to perform a genome-wide study in two multiplex families. This allowed us to identify two additional genes: TMEM5 and ISPD. Because TMEM has a glycosyltransferase domain and ISPD has an isoprenoid synthase domain characteristic of nucleotide diP-sugar transferases, these two proteins are thought to be involved in the glycosylation of dystroglycan. Further screening of 40 families with cobblestone lissencephaly identified nonsense and frameshift mutations in another four unrelated cases for each gene, increasing the mutational rate to 64% in our cohort. All these cases displayed a severe phenotype of cobblestone lissencephaly A. TMEM5 mutations were frequently associated with gonadal dysgenesis and neural tube defects, and ISPD mutations were frequently associated with brain vascular anomalies.

Cobblestone lissencephaly: neuropathological subtypes and correlations with genes of dystroglycanopathies.

Cobblestone lissencephaly represents a peculiar brain malformation with characteristic radiological anomalies, defined as cortical dysplasia combined with dysmyelination, dysplastic cerebellum with cysts and brainstem hypoplasia. Cortical dysplasia results from neuroglial overmigration into the arachnoid space, forming an extracortical layer, responsible for agyria and/or 'cobblestone' brain surface and ventricular enlargement. The underlying mechanism is a disruption of the glia limitans, the outermost layer of the brain. Cobblestone lissencephaly is pathognomonic of a continuum of autosomal recessive diseases with cerebral, ocular and muscular deficits, Walker-Warburg syndrome, muscle-eye-brain and Fukuyama muscular dystrophy. Mutations in POMT1, POMT2, POMGNT1, LARGE, FKTN and FKRP genes attributed these diseases to α-dystroglycanopathies. However, studies have not been able to identify causal mutations in the majority of patients and to establish a clear phenotype/genotype correlation. Therefore, we decided to perform a detailed neuropathological survey and molecular screenings in 65 foetal cases selected on the basis of histopathological criteria. After sequencing the six genes of α-dystroglycanopathies, a causal mutation was observed in 66% of cases. On the basis of a ratio of severity, three subtypes clearly emerged. The most severe, which we called cobblestone lissencephaly A, was linked to mutations in POMT1 (34%), POMT2 (8%) and FKRP (1.5%). The least severe, cobblestone lissencephaly C, was linked to POMGNT1 mutations (18%). An intermediary type, cobblestone lissencephaly B, was linked to LARGE mutations (4.5%) identified for the first time in foetuses. We conclude that cobblestone lissencephaly encompasses three distinct subtypes of cortical malformations with different degrees of neuroglial ectopia into the arachnoid space and cortical plate disorganization regardless of gestational age. In the cerebellum, histopathological changes support the novel hypothesis that abnormal lamination arises from a deficiency in granule cells. Our studies demonstrate the positive impact of histoneuropathology on the identification of α-dystroglycanopathies found in 66% of cases, while with neuroimaging criteria and biological values, mutations are found in 32-50% of patients. Interestingly, our morphological classification was central in the orientation of genetic screening of POMT1, POMT2, POMGNT1, LARGE and FKRP. Despite intensive research, one-third of our cases remained unexplained; suggesting that other genes and/or pathways may be involved. This material offers a rich resource for studies on the affected neurodevelopmental processes of cobblestone lissencephaly and on the identification of other responsible gene(s)/pathway(s).

Contribution of referent pathologists to the quality of trophoblastic diseases diagnosis.

OBJECTIVE: To evaluate the contribution of referent pathologists (RPs) to the quality of diagnosis of trophoblastic diseases and to study the level of diagnostic agreement between the initial pathologists and the RPs. METHODS: This observational retrospective study was carried between 1 November 1999 and 11 January 2011 using the database of the French Trophoblastic Disease Reference Centre in Lyon. All files for hydatiform moles (HMs), trophoblastic tumours and non-molar pregnancies for which there was an initial suspicion of trophoblastic disease were included, whenever there was rereading of the slides by an RP. A total of 1851 HMs and 150 gestational trophoblastic tumours were analysed. RESULTS: When the initial pathologist diagnosed a complete mole, the RP confirmed the diagnosis in 96% of cases. When the initial pathologist diagnosed a partial mole, the RP confirmed the diagnosis in only 64% of cases. For trophoblastic tumours, when the initial pathologist diagnosed a choriocarcinoma, the RP confirmed the diagnosis in 86% of cases. When the initial anatomopathology suggested an invasive mole, the diagnosis was confirmed in 96% of cases. Finally, when the initial diagnosis was a placental site trophoblastic tumour or an epithelioid trophoblastic tumour, the RP confirmed the diagnosis in 60 and 100% of cases, respectively. CONCLUSION: A systematic policy of rereading of slides for all suspicious moles improves the quality of management of trophoblastic diseases at a national level.

Thrombocytopenia-absent radius (TAR) syndrome: a clinical genetic series of 14 further cases. impact of the associated 1q21.1 deletion on the genetic counselling.

Thrombocytopenia-absent radius Syndrome (TAR) is a rare congenital malformation syndrome of complicated transmission. 1q21.1 deletion is necessary but not sufficient for its expression. We report the result of a French multicentric clinical study, and we emphasized on the role of the associated 1q21.1 deletion in the diagnosis and the genetic counselling of our patients. We gathered information on 14 patients presenting with TAR syndrome and referred for genetic counselling in six different university hospitals (8 foetuses, 1 child and 5 adults). Clinical or pathology details, as well as skeletal X-rays were analyzed. Genetic studies were performed by Array-CGH, and Quantitative Multiplex PCR. We demonstrated the very variable phenotypes of TAR syndrome. Female:male ratio was ∼2:1. All patients presented with bilateral radial aplasia/hypoplasia with preserved thumbs. Phocomelia and lower limb anomalies were present in 28% of the cases. We reported the first case of cystic hygroma on affected foetus. 1q21.1 deletions ranging from 330 to 1100 kb were identified in all affected patients. Most of them were inherited from one healthy parent (80%). The identification of a 1q21.1 deletion allowed confirmation of TAR syndrome diagnosis, particularly in foetuses and in atypical phenotypes. Additionally, it allowed accurate genetic counselling, especially when it occurred de novo. These findings allowed discussing the diagnostic criteria and management towards TAR syndrome.

High-throughput sequencing of a 4.1 Mb linkage interval reveals FLVCR2 deletions and mutations in lethal cerebral vasculopathy.

Rare lethal disease gene identification remains a challenging issue, but it is amenable to new techniques in high-throughput sequencing (HTS). Cerebral proliferative glomeruloid vasculopathy (PGV), or Fowler syndrome, is a severe autosomal recessive disorder of brain angiogenesis, resulting in abnormally thickened and aberrant perforating vessels leading to hydranencephaly. In three multiplex consanguineous families, genome-wide SNP analysis identified a locus of 14 Mb on chromosome 14. In addition, 280 consecutive SNPs were identical in two Turkish families unknown to be related, suggesting a founder mutation reducing the interval to 4.1 Mb. To identify the causative gene, we then specifically enriched for this region with sequence capture and performed HTS in a proband of seven families. Due to technical constraints related to the disease, the average coverage was only 7×. Nonetheless, iterative bioinformatic analyses of the sequence data identified mutations and a large deletion in the FLVCR2 gene, encoding a 12 transmembrane domain-containing putative transporter. A striking absence of alpha-smooth muscle actin immunostaining in abnormal vessels in fetal PGV brains, suggests a deficit in pericytes, cells essential for capillary stabilization and remodeling during brain angiogenesis. This is the first lethal disease-causing gene to be identified by comprehensive HTS of an entire linkage interval.

Neonatal tracheal changes following in utero fetoscopic balloon tracheal occlusion in severe congenital diaphragmatic hernia.

OBJECTIVE: To report postnatal tracheal changes after in utero fetoscopic balloon tracheal occlusion in severe congenital diaphragmatic hernia (CDH). DESIGN: Case series. SETTING: Tertiary care center, CDH National Reference Center. PATIENTS: Seven consecutive newborn infants with severe CDH who underwent fetoscopic balloon tracheal occlusion. INTERVENTIONS: Flexible laryngotracheoscopy and histological aspect observed at necropsy in 2 nonsurvivors. RESULTS: All infants displayed elongation and relaxation of the posterior tracheal wall, intermittently obstructing the lumen during tidal breathing. Whereas the cartilage displayed adequate rigidity, the pars membranacea appeared both flaccid and loose. Tracheal widening (tracheomegaly) was seen in all cases. Histology (n = 2) pointed to structural modifications throughout the pars membranacea, that is, loss of epithelial folding and of longitudinal elastic network and focal muscular disruption. The cartilage displayed no visible or histologic changes. The above tracheal changes were not symptomatic, except for a barking cough during increased respiratory efforts. CONCLUSIONS: Tracheal widening and intermittent collapse of the posterior wall of the trachea during tidal breathing was found in 7 consecutive newborns who underwent fetoscopic balloon tracheal occlusion, causing mild clinical symptoms. Endoscopic tracheal assessment might provide useful information in children with CDH, in particular, when they underwent in utero fetoscopic balloon tracheal occlusion.