scholarly journals Identification of a recurrent mosaic KRAS variant in brain tissue from an individual with nevus sebaceous syndrome

2021 ◽  
pp. mcs.a006133
Author(s):  
Timothy E. Green ◽  
Duncan MacGregor ◽  
Susan M. Carden ◽  
Rebekah V. Harris ◽  
Chelsee A. Hewitt ◽  
...  
Keyword(s):  
Brain Tissue ◽  
Temporal Lobe ◽  
Focal Cortical Dysplasia ◽  
Hippocampal Sclerosis ◽  
Digital Pcr ◽  
Droplet Digital Pcr ◽  
Mapk Signalling Pathway ◽  
Mapk Signalling ◽  
Nevus Sebaceous ◽  
Cycle Regulation

Nevus sebaceous syndrome (NSS) is a rare multisystem neurocutaneous syndrome, characterised by a congenital nevus, and may include brain malformations such as hemimegalencephaly or focal cortical dysplasia, ocular and skeletal features. It has been associated with several eponyms including Schimmelpenning and Jadassohn. The isolated skin lesion, nevus sebaceous, is associated with post-zygotic variants in HRAS or KRAS in all patients studied. The RAS proteins encode a family of GTPases that form part of the RAS/MAPK signalling pathway, which is critical for cell cycle regulation and differentiation during development. We studied an individual with nevus sebaceous syndrome with an extensive nevus sebaceous, epilepsy, intellectual disability, and hippocampal sclerosis without pathological evidence of a brain malformation. We utilized high depth gene panel sequencing and sensitive droplet digital PCR to detect and quantify RAS/MAPK gene variants in nevus sebaceous and temporal lobe tissue collected during plastic and epilepsy surgery, respectively. A mosaic KRAS c.34G>T; p.(Gly12Cys) variant, also known as G12C, was detected in nevus sebaceous tissue at 25% variant allele fraction (VAF), at the residue most commonly substituted in KRAS. Targeted droplet digital PCR validated the variant and quantified the mosaicism in other tissues. The variant was detected at 33% in temporal lobe tissue, but was absent from blood and healthy skin. We provide molecular confirmation of the clinical diagnosis of NSS. Our data extends the histopathological spectrum of KRAS G12C mosaicism beyond nevus sebaceous to involve brain tissue and more specifically, hippocampal sclerosis.

scholarly journals The Role of KRAS Mutations in Cortical Malformation and Epilepsy Surgery: A Novel Report of Nevus Sebaceous Syndrome and Review of the Literature

2021 ◽  
Vol 11 (6) ◽  
pp. 793
Author(s):  
Chiara Pepi ◽  
Luca de Palma ◽  
Marina Trivisano ◽  
Nicola Pietrafusa ◽  
Francesca Romana Lepri ◽  
...  
Keyword(s):  
Epilepsy Surgery ◽  
Focal Cortical Dysplasia ◽  
Hippocampal Sclerosis ◽  
Brain Mri ◽  
Seizure Freedom ◽  
Histopathological Diagnosis ◽  
Cortical Malformation ◽  
Cognitive Improvement ◽  
Cortical Malformations ◽  
Nevus Sebaceous

The rare nevus sebaceous (NS) syndrome (NSS) includes cortical malformations and drug-resistant epilepsy. Somatic RAS-pathway genetic variants are pathogenetic in NS, but not yet described within the brain of patients with NSS. We report on a 5-year-old boy with mild psychomotor delay. A brown-yellow linear skin lesion suggestive of NS in the left temporo-occipital area was evident at birth. Epileptic spasms presented at aged six months. EEG showed continuous left temporo-occipital epileptiform abnormalities. Brain MRI revealed a similarly located diffuse cortical malformation with temporal pole volume reduction and a small hippocampus. We performed a left temporo-occipital resection with histopathological diagnosis of focal cortical dysplasia type Ia in the occipital region and hippocampal sclerosis type 1. Three years after surgery, he is seizure-and drug-free (Engel class Ia) and showed cognitive improvement. Genetic examination of brain and skin specimens revealed the c.35G > T (p.Gly12Val) KRAS somatic missense mutation. Literature review suggests epilepsy surgery in patients with NSS is highly efficacious, with 73% probability of seizure freedom. The few histological analyses reported evidenced disorganized cortex, occasionally with cytomegalic neurons. This is the first reported association of a KRAS genetic variant with cortical malformations associated with epilepsy, and suggests a possible genetic substrate for hippocampal sclerosis.

scholarly journals Somatic GNAQ mutation in the forme fruste of Sturge-Weber syndrome

2018 ◽  
Vol 4 (3) ◽  
pp. e236 ◽  
Author(s):  
Michael S. Hildebrand ◽  
A. Simon Harvey ◽  
Stephen Malone ◽  
John A. Damiano ◽  
Hongdo Do ◽  
...  
Keyword(s):  
Brain Tissue ◽  
Molecular Mechanism ◽  
Digital Pcr ◽  
Droplet Digital Pcr ◽  
Cutaneous Manifestations ◽  
Weber Syndrome ◽  
Sturge Weber Syndrome ◽  
Low Levels ◽  
The Brain ◽  
Molecular Evaluation

ObjectiveTo determine whether the GNAQ R183Q mutation is present in the forme fruste cases of Sturge-Weber syndrome (SWS) to establish a definitive molecular diagnosis.MethodsWe used sensitive droplet digital PCR (ddPCR) to detect and quantify the GNAQ mutation in tissues from epilepsy surgery in 4 patients with leptomeningeal angiomatosis; none had ocular or cutaneous manifestations.ResultsLow levels of the GNAQ mutation were detected in the brain tissue of all 4 cases—ranging from 0.42% to 7.1% frequency—but not in blood-derived DNA. Molecular evaluation confirmed the diagnosis in 1 case in which the radiologic and pathologic data were equivocal.ConclusionsWe detected the mutation at low levels, consistent with mosaicism in the brain or skin (1.0%–18.1%) of classic cases. Our data confirm that the forme fruste is part of the spectrum of SWS, with the same molecular mechanism as the classic disease and that ddPCR is helpful where conventional diagnosis is uncertain.

scholarly journals Temporal lobe epilepsy associated with 'triple pathology' of hippocampal sclerosis, focal cortical dysplasia and cavernoma in the ipsilateral frontal lobe

2009 ◽  
Vol 2 (1) ◽  
pp. 34-41 ◽  
Author(s):  
Kazuhiro Samura ◽  
Takato Morioka ◽  
Kimiaki Hashiguchi ◽  
Yasushi Miyagi ◽  
Hiroshi Shigeto ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Frontal Lobe ◽  
Temporal Lobe ◽  
Focal Cortical Dysplasia ◽  
Hippocampal Sclerosis ◽  
Cortical Dysplasia

scholarly journals Droplet digital PCR quantification of norovirus and adenovirus in decentralized wastewater and graywater collections: Implications for onsite reuse

2020 ◽  
Vol 169 ◽  
pp. 115213 ◽  
Author(s):  
Michael A. Jahne ◽  
Nichole E. Brinkman ◽  
Scott P. Keely ◽  
Brian D. Zimmerman ◽  
Emily A. Wheaton ◽  
...  
Keyword(s):  
Digital Pcr ◽  
Droplet Digital Pcr

scholarly journals Development and validation of a method for quantification of common wheat, durum wheat, rye and barley by droplet digital PCR

2021 ◽  
Author(s):  
Christian Schulze ◽  
Anne-Catrin Geuthner ◽  
Dietrich Mäde
Keyword(s):  
Durum Wheat ◽  
Real Time ◽  
Bread Wheat ◽  
Common Wheat ◽  
Real Time Pcr ◽  
Digital Pcr ◽  
Droplet Digital Pcr ◽  
Food Fraud ◽  
Single Genome ◽  
Cereal Species

AbstractFood fraud is becoming a prominent topic in the food industry. Thus, valid methods for detecting potential adulterations are necessary to identify instances of food fraud in cereal products, a significant component of human diet. In this work, primer–probe systems for real-time PCR and droplet digital PCR (ddPCR) for the detection of these cereal species: bread wheat (together with spelt), durum wheat, rye and barley for real-time PCR and ddPCR were established, optimized and validated. In addition, it was projected to validate a molecular system for differentiation of bread wheat and spelt; however, attempts for molecular differentiation between common wheat and spelt based on the gene GAG56D failed because of the genetic variability of the molecular target. Primer–probe systems were further developed and optimized on the basis of alignments of DNA sequences, as well as already developed PCR systems. The specificity of each system was demonstrated on 10 (spelt), 11 (durum wheat and rye) and 12 (bread wheat) reference samples. Specificity of the barley system was already proved in previous work. The calculated limits of detection (LOD95%) were between 2.43 and 4.07 single genome copies in real-time PCR. Based on the “three droplet rule”, the LOD95% in ddPCR was calculated to be 9.07–13.26 single genome copies. The systems were tested in mixtures of flours (rye and common wheat) and of semolina (durum and common wheat). The methods proved to be robust with regard to the tested conditions in the ddPCR. The developed primer–probe systems for ddPCR proved to be effective in quantitatively detecting the investigated cereal species rye and common wheat in mixtures by taking into account the haploid genome weight and the degree of milling of a flour. This method can correctly detect proportions of 50%, 60% and 90% wholemeal rye flour in a mixture of wholemeal common wheat flour. Quantitative results depend on the DNA content, on ploidy of cereal species and are also influenced by comminution. Hence, the proportion of less processed rye is overestimated in higher processed bread wheat and adulteration of durum wheat by common wheat by 1–5% resulted in underestimation of common wheat.

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