Epilepsy in patients with GRIN2A alterations: Genetics, neurodevelopment, epileptic phenotype and response to anticonvulsive drugs.

OBJECTIVE: To delineate the genetic, neurodevelopmental and epileptic spectrum associated with GRIN2A alterations with emphasis on epilepsy treatment. METHODS: Retrospective study of 19 patients (7 females; age: 1-38 years; mean 10.1 years) with epilepsy and GRIN2A alteration. Genetic variants were classified according to the guidelines and recommendations of the American College of Medical Genetics (ACMG). Clinical findings including epilepsy classification, treatment, EEG findings, early childhood development and neurodevelopmental outcome were collected with an electronic questionnaire. RESULTS: 7 out of 19 patients fulfilled the ACMG-criteria of carrying "pathogenic" or "likely pathogenic variants", in twelve patients the alterations were classified as variants of unknown significance. The spectrum of pathogenic/likely pathogenic mutations was as follows: nonsense n = 3, missense n = 2, duplications/deletions n = 1 and splice site n = 1. First seizures occurred at a mean age of 2.4 years with heterogeneous seizure types. Patients were treated with a mean of 5.6 AED. 4/5 patients with VPA had an improved seizure frequency (n = 3 with a truncation: n = 1 missense). 3/5 patients with STM reported an improvement of seizures (n = 2 truncation, n = 1 splicing). 3/5 CLB patients showed an improvement (n = 2: truncation; n = 1 splicing). Steroids were reported to have a positive effect on seizure frequency in 3/5 patients (n = 1 each truncation, splicing or deletion). CONCLUSIONS: Our data indicate that children with epilepsy due to pathogenic GRIN2A mutations present with different clinical phenotypes and a spectrum of seizure types in the context of a pharmacoresistant epilepsy providing information for clinicians treating children with this form of genetically determined epileptic syndrome.

Simultaneous solid-phase extraction and gas chromatographic-mass spectrometric determination of hemoglobin adducts from tobacco-specific nitrosamines and aromatic amines.

A new method for the simultaneous determination of hemoglobin adducts from aromatic amines and tobacco-specific nitrosamines (TSNA) is described. After mild base-catalysed hydrolysis releasing aromatic amines and the TSNA adduct 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB), the extraction, cleanup, and concentration are performed by a one-step procedure using C18 cartridges. Determination in the picograms per gram of hemoglobin range by gas chromatography-mass spectrometry with negative chemical ionization requires a separate derivatization procedure with pentafluoropropionic anhydride and pentafluorobenzoylchloride for aromatic amines and HPB, respectively. The method is shown to be quantitative, reproducible, and applicable to the determination of hemoglobin adducts from monocyclic and bicyclic aromatic amines as well as TSNA in smokers and nonsmokers.

Biomonitoring of hemoglobin adducts: aromatic amines and tobacco-specific nitrosamines.

A new analytical procedure has been developed for the simultaneous determination of human hemoglobin adducts from aromatic amines and tobacco-specific nitrosamines. These tobacco-related hemoglobin adducts were determined in nonsmokers, smokers, and users of nasal snuff. Adducts from aminobiphenyl compounds are good biomarkers of exposure to tobacco smoke; they are not elevated in users of nasal snuff. However, a significant contribution of environmental exposure to aromatic amines and/or the corresponding nitroaromatics makes it difficult to evaluate passive exposure to tobacco smoke. The best biomarkers for exposure to tobacco smoke should in theory be adducts arising from tobacco-specific nitrosamines. The common adduct from N'-nitrosonornicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone releases 4-hydroxy-1-(3-pyridyl)-1-butanone from hemoglobin upon mild alkaline hydrolysis and only marginal differences are found in the adduct level in smokers and nonsmokers. The reason for this observation is not yet understood and is currently under investigation. However, the adduct formed by tobacco-specific nitrosamines is well suited for the detection of oral and nasal tobacco use. Only by simultaneous determination of both adducts formed by aromatic amines and tobacco-specific nitrosamines is it possible to differentiate between nonsmokers, smokers, and nasal snuff users.