Friday, November 10, 2017

FOXG1 syndrome

Inspired by a patient

Mitter D, Pringsheim M, Kaulisch M, Plümacher KS, Schröder S, Warthemann R, Abou Jamra R, Baethmann M, Bast T, Büttel HM, Cohen JS, Conover E, Courage C, Eger A, Fatemi A, Grebe TA, Hauser NS, Heinritz W, Helbig KL, Heruth M, Huhle D, Höft K, Karch S, Kluger G, Korenke GC, Lemke JR, Lutz RE, Patzer S, Prehl I, Hoertnagel K, Ramsey K, Rating T, Rieß A, Rohena L, Schimmel M, Westman R, Zech FM, Zoll B, Malzahn D, Zirn B, Brockmann K. FOXG1 syndrome: genotype-phenotype association in 83 patients with FOXG1 variants. Genet Med. 2017 Jun 29.
doi: 10.1038/gim.2017.75. [Epub ahead of print]



The study aimed at widening the clinical and genetic spectrum and assessing genotype-phenotype associations in FOXG1 syndrome due to FOXG1 variants.MethodsWe compiled 30 new and 53 reported patients with a heterozygous pathogenic or likely pathogenic variant in FOXG1. We grouped patients according to type and location of the variant. Statistical analysis of molecular and clinical data was performed using Fisher's exact test and a nonparametric multivariate test.


Among the 30 new patients, we identified 19 novel FOXG1 variants. Among the total group of 83 patients, there were 54 variants: 20 frameshift (37%), 17 missense (31%), 15 nonsense (28%), and 2 in-frame variants (4%). Frameshift and nonsense variants are distributed over all FOXG1 protein domains; missense variants cluster within the conserved forkhead domain. We found a higher phenotypic variability than previously described. Genotype-phenotype association revealed significant differences in psychomotor development and neurological features between FOXG1 genotype groups. More severe phenotypes were associated with truncating FOXG1 variants in the N-terminal domain and the forkhead domain (except conserved site 1) and milder phenotypes with missense variants in the forkhead conserved site 1.


These data may serve for improved interpretation of new FOXG1 sequence variants and well-founded genetic counseling. 

Zhang Q, Wang J, Li J, Bao X, Zhao Y, Zhang X, Wei L, Wu X. Novel FOXG1 mutations in Chinese patients with Rett syndrome or Rett-like mental retardation. BMC Med Genet. 2017 Aug 29;18(1):96.

We aimed to delineate clinical phenotypes associated with FOXG1 mutations in Chinese patients with Rett syndrome (RTT) or RTT-like mental retardation (MR).
Four hundred and fifty-one patients were recruited, including 418 with RTT and 33 with RTT-like MR. Gene mutations were identified by a target capture method and verified by Sanger sequencing.
Four FOXG1 mutations were detected in four patients (three with RTT and one with RTT-like MR), including one previously described mutation and three novel mutations. These mutations included one missense and three micro-insertion mutations. Overall, 0.7% (3/418) of patients who had RTT in our cohort had FOXG1 mutations. All patients had early global developmental delays followed later by severe mental retardation. None of the patients acquired speech or purposeful hand movements, and all of them presented with severe hypotonia, epilepsy, and hypoplasia of the corpus callosum.
Our findings extend the spectrum of FOXG1 mutations and the clinical features of RTT in Chinese patients. We recommend that patients with congenital RTT and Rett-like MR, especially those with brain malformations, such as hypoplasia of the corpus callosum, should be tested for FOXG1 mutations. 

Carecchio M, Mencacci NE. Emerging Monogenic Complex Hyperkinetic Disorders. Curr Neurol Neurosci Rep. 2017 Oct 30;17(12):97. 

Hyperkinetic movement disorders can manifest alone or as part of complex phenotypes. In the era of next-generation sequencing (NGS), the list of monogenic complex movement disorders is rapidly growing. This review will explore the main features of these newly identified conditions.

Mutations in ADCY5 and PDE10A have been identified as important causes of childhood-onset dyskinesias and KMT2B mutations as one of the most frequent causes of complex dystonia in children. The delineation of the phenotypic spectrum associated with mutations in ATP1A3, FOXG1, GNAO1, GRIN1, FRRS1L, and TBC1D24 is revealing an expanding genetic overlap between epileptic encephalopathies, developmental delay/intellectual disability, and hyperkinetic movement disorders,. Thanks to NGS, the etiology of several complex hyperkinetic movement disorders has been elucidated. Importantly, NGS is changing the way clinicians diagnose these complex conditions. Shared molecular pathways, involved in early stages of brain development and normal synaptic transmission, underlie basal ganglia dysfunction, epilepsy, and other neurodevelopmental disorders.

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