Genetic epilepsy syndromesGene: TFE3
This gene was reviewed for the ID panel. Epilepsy has been reported in 5 unrelated affected individuals (in 2 studies). Please consider upgrade to green/amber rating.
7 unrelated individuals with de novo TFE3 pathogenic variants have been reported in the following studies:
 Villegas et al (2019 - PMID: 30595499) - Lysosomal Signaling Licenses Embryonic Stem Cell Differentiation via Inactivation of Tfe3 [5 individuals]
 Diaz et al (2019 - PMID: 31833172) - TFE3-associated neurodevelopmental disorder: A distinct recognizable syndrome [2 additional individuals]
Overlapping features observed in almost all included DD and severe ID (7/7), coarse facial features (6/7) as well as blaschkoid pigmentary mosaicism (6/7). Epilepsy was reported in 5/7. Variable other features observed in some/few included (by decreasing order of frequency): hypotonia, developmental regression, obesity, hand stereotypies, hepatomegaly, umbilical hernia, ASD, recurrent otitis media, hypoglycemia, etc.
TFE3 encodes transcription factor for immunoglobulin heavy-chain enhancer 3. The gene lies on Xp11.23.
All individuals reported to date have been found to harbor de novo variants affecting exons 3 or 4. Six different missense variants have been reported. A suspected ectopic nuclear gain-of-function effect has been proposed in Ref1. One additional similarly affected individual harbored a canonical splice site variant (NM_006521.4:c.780+1G>A in intron 4) predicted to lead to in-frame skipping of exon 4 (Ref2).
6/7 affected individuals were females. Random X-chromosome inactivation (XCI) was shown for an individual with blaschkoid pigmentary mosaicism. It has been commented and shown that the (single) female without BPM had skewed XCI (Ref1).
A single male was also affected. This individual harbored a de novo mosaic variant (65% in blood) (Ref1).
Previous investigations included among others:
- metabolic work-up in some individuals (Refs1/2), also for suspected lysosomal disorders (due to coarse facial features, hepatomegaly, hypoglycemia, etc)
- conventional karyotype in some cases (for one individual a mosaic t(X;11) with Xp22.3 microdeletion was demonstrated in Ref1, but this did not contain genes for ID/epilepsy reason why WES was subsequently pursued)
- SNP-CMA (skin & blood or skin only - for the 2 individuals in Ref2)
- For individuals from Ref2 variable IKBKG genetic testing, testing for Angelmann/Beckwith-Wiedemann syndrome, ID/epilepsy/ASD gene panel testing was carried out.
Exome sequencing in some cases in Ref2 revealed additional de novo variants in other genes not thought to contribute to the phenotype due to the inheritance mode (AR with absence of other variant in trans) or due to in silico predictions predicting a tolerated/benign effect for the respective variant(s) (eg. for NCOR1).
To the best of my understanding (?) and better summarized by VanHook AM (2019 - DOI: 10.1126/scisignal.aax0926 - https://stke.sciencemag.org/content/12/570/eaax0926 ):
Sequestering of Tfe3 in the cytoplasm (through recruitment to the lysosomal membrane) prevents its role as transcription factor in the nucleus. Mutations preventing its recruitment to lysosomes, prevent cytoplasmic sequestration, enabling Tfe3 to enter the nucleus and in turn affect (/block) stem cell differentiation. Exons 3 and 4 are suggested to form a structure important for cytoplasmic Tfe3 inactivation. Villegas et al studied Tfe3 KO embryonic stem cells (ESCs) expressing murine alleles (Q118P and P185L) corresponding to mutations observed in affected individuals (Q119P/P186L). The variants were shown to affect Tfe3 localization (/induce nuclear localization) and prevent spontaneous differentiation of ESCs into neural progenitors. Signalling pathways and functional effects (as proposed by Villegas et al) are summarized in the reference above.
Created: 27 Dec 2019, 10:54 p.m. | Last Modified: 27 Dec 2019, 10:54 p.m.
Panel Version: 2.0
Mode of inheritance
Global developmental delay; Intellectual disability; Abnormality of skin pigmentation; Coarse facial features; Seizures
Mode of pathogenicity
Review and rating collated by Tracy Lester (Oxford Medical Genetics Laboratories Oxford University Hospitals NHS Foundation Trust, 2019_02_06) on behalf of Wessex and West Midlands GLH for GMS Neurology specialist test group, for Clinical Indication R59 'Early onset or syndromic epilepsy'. Review contributors: Alison Callaway and John Taylor. Suggested gene rating: Red.
Created: 6 Aug 2019, 8:38 p.m. | Last Modified: 6 Aug 2019, 8:38 p.m.
Panel Version: 1.189
This gene appears to be associated with renal cell carcinoma- no obvious link to seizure/epilepsy.
Created: 6 Aug 2019, 8:31 p.m. | Last Modified: 6 Aug 2019, 8:31 p.m.
Panel Version: 1.188
Mode of inheritance
Renal cell carcinoma, papillary, 300854
I can't find any published evidence to link this gene with rare monogenic disorders.
Created: 22 Aug 2018, 5:38 a.m.
Source Wessex and West Midlands GLH was added to TFE3.
Source NHS GMS was added to TFE3.
Zornitza Stark: I can't find any published evi
Gene: tfe3 has been classified as Amber List (Moderate Evidence).
Expert Review Amber was added to TFE3. Panel: Genetic Epilepsy Syndromes
TFE3 was added to Genetic Epilepsy Syndromes panel. Sources: Victorian Clinical Genetics Services
TFE3 was created by Sarah Leigh