Background
Postzygotic mutations in FGFR2 have been identified in mosaic forms of acne, keratinocytic epidermal nevi, nevoid acanthosis nigricans / rounded and velvety epidermal nevus and in two ...fetuses with papillomatous pedunculated sebaceous nevus (PPSN).
Objectives
To determine the clinical and genetic characteristics of children with cerebriform, papillomatous and pedunculated variants of sebaceous nevi.
Methods
Infants diagnosed with sebaceous nevi characterized by a cerebriform, papillomatous and/or pedunculated morphology over a 10‐year period (2010–2019) at three paediatric dermatology centres in Switzerland and France were included in this case series. Clinical and histological characteristics were assessed. Next‐generation sequencing was used to assess for FGFR2 mutations.
Results
All nevi were located on the head, with a rounded or linear shape and a typical cerebriform, sometimes papillomatous and pedunculated, surface. No associated extracutaneous anomalies were found. Nevi harboured postzygotic mutations in the transmembrane domain of FGFR2 in 6/8 children (75%), either the known specific p.(Cys382Arg) mutation in 5 cases, or a novel mutation, p.(Val395Asp), in one.
Conclusions
We found an exquisite genotype–phenotype correlation in these rare nevi, with specific postzygotic mutations in the transmembrane domain of FGFR2. As not all lesions were truly papillomatous and pedunculated, the term cerebriform sebaceous nevus (CSN) appears more suitable than PPSN to describe this entity. The cerebriform pattern of CSN is reminiscent of cutis gyrata, as seen in Beare–Stevenson syndrome, which is caused by closely related germline FGFR2 mutations. While clinically impressive, CSN seem to carry a good prognosis and a low risk for extracutaneous associations.
Abstract
Grange syndrome (GRNG—MIM#135580) is a rare recessive disorder associating variable features including diffuse vascular stenosis, brachysyndactyly, osteopenia with increased bone fragility, ...cardiac malformations, and variable developmental delay. Since its first description in 1998, only 15 individuals from 10 families have been reported, carrying homozygous or compound heterozygous frameshift or nonsense variants in
YY1AP1
. In a patient with cutaneous and bone syndactyly and a hemorrhagic stroke at the age of 16 months, consistent with a clinical diagnosis of GRNG, we performed exome sequencing after negative array‐CGH and congenital limb malformation panel results. Copy number variant analysis from exome data identified a homozygous intragenic out‐of‐frame deletion of 1.84 kb encompassing exons seven and eight of
YY1AP1,
confirming a molecular diagnosis of GRNG. Genetic counseling led to the identification of additional family members compatible with GRNG. Here, we provide new insights into the phenotypic variability associated with GRNG and highlight the utility of the detection of small copy number variants to identify the molecular causes of heterogeneous malformative genetic disorders.
Marfanoid habitus (MH) combined with intellectual disability (ID) is a genetically and clinically heterogeneous group of overlapping disorders. We performed exome sequencing in 33 trios and 31 single ...probands to identify novel genes specific to MH‐ID. After the search for variants in known disease‐causing genes and non‐disease‐causing genes with classical approaches, we searched for variants in non‐disease‐causing genes whose pLI was above 0.9 (ExAC Consortium data), in which truncating variants were found in at least 3 unrelated patients. Only DLG4 gene met these criteria. Data from the literature and various databases also indicated its implication in ID. DLG4 encodes post‐synaptic density protein 95 (PSD‐95), a protein expressed in various tissues, including the brain. In neurons, PSD‐95 is located at the post‐synaptic density, and is associated with glutamatergic receptor signaling (NMDA and AMPA). PSD‐95 probably participates in dendritogenesis. Two patients were heterozygous for de novo frameshift variants and one patient carried a a consensus splice site variant. Gene expression studies supported their pathogenicity through haploinsufficiency and loss‐of‐function. Patients exhibited mild‐to‐moderate ID, similar marfanoid features, including a long face, high‐arched palate, long and thin fingers, pectus excavatum, scoliosis and ophthalmological manifestations (nystagmus or strabismus). Our study emphasizes the role of DLG4 as a novel post‐synaptic‐associated gene involved in syndromic ID associated with MH.
Exome sequencing (ES) represents the first-tier diagnostic test in patients presenting with syndromic developmental delay with suspected monogenic etiology. Yet, about 50% of these patients remain ...unsolved, arguing the interest to extend the genetic investigations beyond the protein-coding genome and to integrate multi-omics approaches. We launched a multi-centric pilot study gathering 53 unsolved patients, after trio ES and array-CGH results, presenting with heterogeneous mild to severe syndromic intellectual disabilities. We performed genome sequencing (GS) combined with transcriptome analysis, highlighting a molecular cause in 32% of the cohort (18/53 patients). GS identified 7 causative structural variants, including 1 deletion, 2 balanced inversions, 1 balanced translocation and 3 complex variants. The molecular readouts of such variants were all validated and furtherly investigated by RNAseq. One deep intronic SNV causing the activation of a cryptic exon, changing the open reading frame of the transcript, was detected by RNAseq. Two frameshift-causing indels were identified in protein-coding regions not captured by ES. Three variants were identified in genes not yet known as disease-causing at the time of the ES analysis. Finally, genotype-phenotype correlation could establish 3 additional diagnoses not identified during the ES analysis. In addition, we detected 2 complex structural variants of unknown significance, not resolvable by short-read GS, as well as new candidate genes identified through RNA-seq differential expression analysis. Overall, GS and RNAseq analyses allowed the identification of the molecular mechanisms underlying 1/3 of previously unsolved patients, and additional candidate variants requiring further investigation (3rd-generation sequencing, 3C techniques) to demonstrate their causality.
High-affinity transporters for norepinephrine (NE) and serotonin (5-HT), which ensure neurotransmitter clearance at the synapse, are the principal targets of widely used antidepressant drugs. ...Antidepressants targeting these high-affinity transporters, however, do not provide positive treatment outcomes for all patients. Other monoamine transport systems, with lower affinity, have been detected in the brain, but their role is largely unknown. Here we report that OCT2, a member of the polyspecific organic cation transporter (OCT) family, is expressed notably in the limbic system and implicated in anxiety and depression-related behaviors in the mouse. Genetic deletion of OCT2 in mice produced a significant reduction in brain tissue concentrations of NE and 5-HT and in ex vivo uptake of both these neurotransmitters in the presence of the dual 5-HT-NE transport blocker, venlafaxine. In vivo clearance of NE and 5-HT evaluated using microiontophoretic electrophysiology was diminished in the hippocampus of OCT2(-/-) mice in the presence of venlafaxine, thereby affecting postsynaptic neuronal activity. OCT2(-/-) mice displayed an altered sensitivity to acute treatments with NE- and/or 5-HT-selective transport blockers in the forced-swim test. Moreover, the mutant mice were insensitive to long-term venlafaxine treatment in a more realistic, corticosterone-induced, chronic depression model. Our findings identify OCT2 as an important postsynaptic determinant of aminergic tonus and mood-related behaviors and a potential pharmacological target for mood disorders therapy.
Changes in serotonin(2C) receptor (5-HTR2c) editing, splicing and density were found in conditions such as depression and suicide, but mechanisms explaining the changes in 5-HTR2c function are ...unknown. Thus, mice expressing only the fully edited VGV isoform of 5-HTR2c, in which clinically relevant behavioral changes are associated with alterations in splicing and receptor density, were studied. VGV mice displayed enhanced anxiety-like behavior in response to a preferential 5-HTR2c agonist in the social interaction test. Nearly half of interactions between pairs of VGV congeners consisted of fighting behaviors, whereas no fighting occurred in wild-type (WT) mice. VGV mice also exhibited a striking increase in freezing behaviors in reaction to an innately aversive ultrasonic stimulus. This behavioral phenotype occurred in conjunction with decreased brain 5-HT turnover during stress. These functional data were put in relation with the 5-HTR2c mRNA splicing process generating a truncated protein (5-HTR2c-Tr) in addition to the full-length receptor (5-HTR2c-Fl). 5-HTR2c-Tr mRNA was less abundant in many brain regions of VGV mice, which concomitantly had more 5-HTR2c than WT mice. Fluorescence resonance energy transfer and bioluminescence resonance energy transfer studies in transfected living HEK293T cells showed that 5-HTR2c-Tr interacts with 5-HTR2c-Fl. The 5-HTR2c-Tr was localized in the endoplasmic reticulum where it retained 5-HTR2c-Fl, preventing the latter to reach the plasma membrane. Consequently, 5-HTR2c-Tr decreased (3)H-mesulergine binding to 5-HTR2c-Fl at the plasma membrane in a concentration-dependent manner and more strongly with edited 5-HTR2c-Fl. These results suggest that 5-HTR2c pre-mRNA editing and splicing are entwined processes determining increased 5-HTR2c levels in pathological conditions through a deficit in 5-HTR2c-Tr.
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