Rare genetic causes of microcephaly and megalencephaly

Microcephaly has been defined as an occipitofrontal head circumference of equal to or less than 2-3 standard deviations below the mean related for age and gender. It may develop prenatally (congenital microcephaly) or postnatally and may have genetic or nongenetic causes. Although a wide spectrum of genetic defects can result in microcephaly, traditionally a group of microcephalies has been distinguished as autosomal recessive primary microcephaly (MicroCephaly Primary Hereditary, MCPH). Both megalencephaly and macrocephaly have been defined as conditions with head circumference that exceeds the mean by 2 or more standard deviations (SD) for age and gender. Megalencephaly refers to an enlarged brain due to increased growth of cerebral structures during brain development, while in macrocephaly the enlarged head is the result of hydrocephalus, subdural fluid collections or intracranial masses. Megalencephaly can be idiopathic, or can be associated with metabolic disorders, or genetic syndromes. Objectives The aims of this study were to characterize the phenotypic and genotypic features of three patients with autosomal recessive primary microcephaly and two children with megalencephaly. Methods Thorough assessment of the patients has been carried out including physical and neurological examination and developmental testing. Chromosomal analysis and array comparative genome hybridization (aCGH) were performed, followed by next generation sequencing. Whole exome sequencing (WES) was performed for three patients with autosomal recessive primary microcephaly (ASPM and WDR62 genes, CentoXome® at Centogene AG, Rostock, Germany). The Illumina Trusight One Exome Sequencing Panel (Illumina Inc., San Diego, California, USA) was used for the analysis of mutations in two genes (FOXP1 and PTCH1) in a girl with megalencephaly (Department of Paediatrics, University of Szeged). Multiplex targeted sequencing was applied using single molecule molecular inversion probes in the patient with megalencephaly and AKT3 mutation (in collaboration with scientists in the USA). The mutations were confirmed by Sanger sequencing.5 Patients and Results Patient 1./ A novel homozygous nonsense variant in the ASPM gene [c.7323T>A, p.(Tyr2441Ter)] in exon 18 in a boy was associated with congenital microcephaly, severe developmental delay and MRI features of cortical dysplasia and polymicrogyria. Patients 2 and 3./ A boy and a girl had the same novel homozygous missense variant [c.668T>C, p.(Phe223Ser)] in exon 6 in the WDR62 gene. They had hemispherical asymmetry and diffuse pachygyria on the MRI in addition to microcephaly and severe developmental delay, Haplotype analysis suggested close relationship between the families of these patients. Patient 4./ A girl with extreme megalencephaly and profound intellectual disability had de novo heterozygous variants in exon 18 of the FOXP1 [c.1573C>T, p.(Arg525Ter)] gene and exon 17 of the PTCH1 [c.2834delGinsAGATGTTGTGGACCC, p.(Arg945GlnfsTer22)] gene. The PTCH1 mutation was novel. Patient 5./ Megalencephaly, diffuse polymicrogyria and delayed development were the characteristic features of a boy with an activating de novo germline heterozygous missense variant [c.1393C>T; p.(Arg465Trp)] in exon 13 of the AKT3 gene, which encodes a member of the PI3K (phosphatidylinositol-3-kinase)–AKT (AK mouse + Transforming or Thymoma)-mTOR) pathway. Conclusions Rare autosomal recessive primary microcephaly (MCPH) due to mutations in ASPM and WDR62 might be the result of abnormal function of the centrosomes, which organize the separation of chromosome copies during cell division. Megalencephaly in association with pathogenic mutations in two genes (FOXP1 and PTCH1) in the same individual is exceptionally rare and the severe phenotype might have been the result of the combined effect of this genetic constellation. Activating mutation in a gene (AKT3) encoding a member of the PI3K-AKT-mTOR pathway in association with megalencephaly is also a rare condition. It is justified therefore, to devote this study to the thorough work up of these patients; it is in line with the international endeavour to identify the genetic causes of rare diseases by applying new technologies, particularly array methods and next generation sequencin

Mutations of AKT3 are associated with a wide spectrum of developmental disorders including extreme megalencephaly

Mutations of genes within the phosphatidylinositol-3-kinase (PI3K)-AKT-MTOR pathway are well known causes of brain overgrowth (megalencephaly) as well as segmental cortical dysplasia (such as hemimegalencephaly, focal cortical dysplasia and polymicrogyria). Mutations of the AKT3 gene have been reported in a few individuals with brain malformations, to date. Therefore, our understanding regarding the clinical and molecular spectrum associated with mutations of this critical gene is limited, with no clear genotype–phenotype correlations. We sought to further delineate this spectrum, study levels of mosaicism and identify genotype–phenotype correlations of AKT3-related disorders. We performed targeted sequencing of AKT3 on individuals with these phenotypes by molecular inversion probes and/or Sanger sequencing to determine the type and level of mosaicism of mutations. We analysed all clinical and brain imaging data of mutation-positive individuals including neuropathological analysis in one instance. We performed ex vivo kinase assays on AKT3 engineered with the patient mutations and examined the phospholipid binding profile of pleckstrin homology domain localizing mutations. We identified 14 new individuals with AKT3 mutations with several phenotypes dependent on the type of mutation and level of mosaicism. Our comprehensive clinical characterization, and review of all previously published patients, broadly segregates individuals with AKT3 mutations into two groups: patients with highly asymmetric cortical dysplasia caused by the common p.E17K mutation, and patients with constitutional AKT3 mutations exhibiting more variable phenotypes including bilateral cortical malformations, polymicrogyria, periventricular nodular heterotopia and diffuse megalencephaly without cortical dysplasia. All mutations increased kinase activity, and pleckstrin homology domain mutants exhibited enhanced phospholipid binding. Overall, our study shows that activating mutations of the critical AKT3 gene are associated with a wide spectrum of brain involvement ranging from focal or segmental brain malformations (such as hemimegalencephaly and polymicrogyria) predominantly due to mosaic AKT3 mutations, to diffuse bilateral cortical malformations, megalencephaly and heterotopia due to constitutional AKT3 mutations. We also provide the first detailed neuropathological examination of a child with extreme megalencephaly due to a constitutional AKT3 mutation. This child has one of the largest documented paediatric brain sizes, to our knowledge. Finally, our data show that constitutional AKT3 mutations are associated with megalencephaly, with or without autism, similar to PTEN-related disorders. Recognition of this broad clinical and molecular spectrum of AKT3 mutations is important for providing early diagnosis and appropriate management of affected individuals, and will facilitate targeted design of future human clinical trials using PI3K-AKT pathway inhibitors

De Novo Interstitial Microdeletion at 1q32.1 in a 10-Year-Old Boy with Developmental Delay and Dysmorphism

A 10-year-old boy was referred with developmental delay and dysmorphism. Genomewide aCGH microarray analysis detected a de novo 3.7 Mb deletion at 1q32.1: arr 1q32.1(199,985,888-203,690,832)x1 dn [build HG19]. This first report of a deletion in this region implies a critical role for dosage-sensitive genes within 1q32.1 in neurological development. This is consistent with previously reported duplications of this region in patients with a similar phenotype

De Novo Interstitial Microdeletion at 1q32.1 in a 10-Year-Old Boy with Developmental Delay and Dysmorphism

A 10-year-old boy was referred with developmental delay and dysmorphism. Genomewide aCGH microarray analysis detected a de novo 3.7 Mb deletion at 1q32.1: arr 1q32.1(199,985,888-203,690,832)x1 dn [build HG19]. This first report of a deletion in this region implies a critical role for dosage-sensitive genes within 1q32.1 in neurological development. This is consistent with previously reported duplications of this region in patients with a similar phenotype

Vaping-Related Adverse Events and Perceived Health Improvements: A Cross-Sectional Survey among Daily E-Cigarette Users

Web-based samples of e-cigarette users commonly report significant vaping-related health improvements (HIs) and mild adverse events (AEs). This cross-sectional study with in-person interviewing data collection examined self-reported AEs and perceived HIs among Hungarian adult current daily exclusive e-cigarette (n = 65) and dual users (n = 127), and former daily e-cigarette users (n = 91) in 2018. Logistic regression was used to evaluate associations between reporting any AEs/HIs, vaping status, and covariates. More former users (52.7%) reported AEs than current users (39.6%; p = 0.038). Exclusive and dual daily users reported similar rates of AEs (44.6% and 37.0%, respectively; p = 0.308). More current users (46.9%) experienced HIs than former users (35.2%; p = 0.064). Exclusive daily users were more likely to report HIs than dual users (63.1% versus 38.6%; p = 0.001). Former user status and smoking cessation/reduction reasons increased the odds of reporting AEs, whereas nicotine-containing e-liquid use and older age decreased the odds of reporting AEs. Exclusive vaper status, using advanced generation devices, and smoking cessation/reduction reasons increased the odds of experiencing HIs. This study, which used a traditional data collection methodology, found a higher rate of AEs and a lower rate of HIs compared to web-based surveys. Our results highlight that experiencing AEs and HIs is affected by users’ characteristics, in addition to the device and e-liquid type

A dohányzás és az e-cigaretta-használat epidemiológiája a felnőtt magyar népesség körében 2018-ban

Bevezetés: Nagyszámú kutatás igazolta, hogy a dohányzás növeli a legjelentősebb krónikus betegségek kockázatát. Habár 2009 óta csökkenő tendenciát mutat Magyarországon a hagyományos dohányzók aránya, az e-cigarettát ki- próbálóké az utóbbi években folyamatosan növekszik. Célkitűzés: A 2018-ban a felnőtt lakosság körében végzett Népegészségügyi Felmérés dohányzásra és e-cigaretta- használatra vonatkozó eredményeinek bemutatása az előző vizsgálatok tükrében. Módszer: A kérdőíves felmérésben 1586 fő került személyesen lekérdezésre. Az iteratív súlyozás a többlépcsős mintavételi designhatást és a 2016-os mikrocenzus adatait vette figyelembe. Eredmények: 2018-ban a dohányzók aránya a magyar felnőtt lakosság körében 28,7% (95% MT: 26,3–31,1%), az e-cigarettát használók aránya pedig 1,7% (95% MT: 1,1–2,5%) volt. Az iskolai végzettség a 65 év alattiak esetében a dohányzást befolyásoló tényező volt (EH: 3,32; 95% MT: 2,53–4,34), de a 65 éves és annál idősebb korcsoportban már nem (EH: 1,11; 95% MT: 0,59–2,09). Az e-cigarettát kipróbálók és használók között a leginkább említett (54,3% 95% MT: 44,0–64,5%) motivációs tényezőcsoport a dohányzásról való leszokással, az ártalomcsökkentéssel és a visszaesés megelőzésével volt kapcsolatos. A 65 éves és idősebb korcsoportban a dohányzók aránya 2015-höz képest emelkedett. 2018-ban az alapfokú iskolai végzettségűek körében volt a legmagasabb a dohányzók aránya, míg 2014- ben az érettségivel nem rendelkező középfokú végzettségűek körében. Következtetés: Bár összességében csökkent, az alacsony iskolai végzettségűek és az idősek körében emelkedett a do- hányzók aránya Magyarországon. Az e-cigarettát kipróbálók és használók száma növekvő tendenciát mutat hazánk- ban. Eredményeink az alacsony iskolai végzettségűekre kiemelten fókuszáló, megelőző és leszokást támogató nép- egészségügyi alprogramokat is tartalmazó komplex beavatkozást sürgetnek