Trofinetide. Glycine-proline-glutamate (GPE) analogue, Treatment of Rett syndrome, Treatment of fragile X syndrome

2021 ◽  
Vol 46 (1) ◽  
pp. 29
Author(s):  
B.E. Collins ◽  
J.L. Neul
2020 ◽  
Vol 17 (1) ◽  
Author(s):  
John Paul Oliveria ◽  
Zhuo Jun Li

Astrocytes play an important role in the development of functional neural circuits in the brain. They are responsible for coordinating synapse formation and function, axon guidance, and ensuring neuronal survival. Normal astrogenesis begins during late gestation. Neural stem cells (NSCs) become primarily gliogenic and differentiate to become astrocyte precursors. Through local proliferation and functional maturation, the precursors develop into mature astrocytes, which can either be fibrous or protoplasmic. Astrogenesis is regulated by both cell intrinsic programs and cell extrinsic cues. Intrinsic chromatin changes, such as demethylation of astrocyte-specific genes, allows the NSCs to become responsive to astrocyte-inducing exogenous cues. These cues involve a collaboration of multiple pathways, namely the Notch pathway, the bone morphogenetic protein (BMP) signaling pathway, interleukin-6 (IL-6) signaling, and the Janus Kinase/Signal Transducer and Activator of Transcription (JAK-STAT) pathway. Together, they allow for normal astrogenesis to occur. However, disruption to these pathways lead to abnormal astrocyte development and results in pathologies such as the Fragile X Syndrome (FXS) and Rett Syndrome (RS). Both neurodevelopmental disorders are a result of genetic mutations that causes either transcriptional silence or transcriptional activation at inappropriate stages during development. These genetic mutations result in depressed astrocyte function in FXS, and the overexcitement of astrocytes in RS. The current hypothesis under investigation is that altered gene transcription during neurodevelopment disrupts astrogenesis, and subsequently, the behavior and function of mature astrocytes in the brain. Future research should focus on understanding the timing of the transition from neurogenesis to astrogenesis and identifying astrocyte-specific markers that are critical to its function in neurodevelopment.


2017 ◽  
Vol 25 (1-2) ◽  
pp. 47-51
Author(s):  
Elena Belousova ◽  
Vladimir Sukhorukov ◽  
Marina Dorofeeva ◽  
Lev Shagam ◽  
Dmitrii V. Vlodavetz

SummaryIntroduction.There are some genetic disorders with combination of mental retardation, epilepsy and autism in which the abnormal mammalian Target of Rapamycin (m-TOR) signaling is implicated. The most important of them is tuberous sclerosis complex (TSC), but the disturbances of the m-TOR pathway can also be detected in Rett syndrome (RS), Fragile X syndrome and Down syndrome. We describe the rare case of co-occurrence of TSC and RS.Case study.The female child was born at term by normal delivery after a non-complicated pregnancy. Family history was negative for epilepsy and mental retardation. The neonatal period was uneventful and psychomotor development was normal before the child became 1.5 years old. At the age of 18 months the girl developed hand-wringing stereotypes, facial hypotonia, ataxia and gait apraxia. She lost eye-to-eye contact and verbal contact with relatives, and became indifferent to the surrounding environment. When she was 2 years old, focal adversive seizures started which were readily controlled with carbamazepine. Cerebral cortical and subcortical tubers, cerebral white-matter radial migration lines and subependymal nodules on brain MRI together with hypomelanotic macules suggested the presence of TSC. Diagnosis was confirmed at age of 3 years by a heterozygous mutation c.5161-2A>G inTSC2gene on chromosome 16p13. But the rude regression of psychomotor development and speech, autistic features alongside with characteristic hand-wringing stereotypes were unexplained until at age of 4.5 years RS was diagnosed by finding a heterozygous missense mutation in exon 4 of theMECP2gene c.455C>T, resulting in a P152R substitution in the methyl-binding domain of the protein. At age of 5 the patient is not able to walk independently and has no expressive speech, she is autistic, has ataxia, limb rigidity, hyperreflexia, lack of purposeful hand movements, verbal and motor stereotypies.Discussion.The presence of two mutations (one characteristic forTSC2and one – characteristic for RS) significantly worsened the developmental and motor delay and autistic features in our patient. Dysregulation of m-TOR way is well established in TSC and recently described in RS, Down syndrome and Fragile X syndrome.


2021 ◽  
Vol 15 ◽  
Author(s):  
Snow Bach ◽  
Stephen Shovlin ◽  
Michael Moriarty ◽  
Barbara Bardoni ◽  
Daniela Tropea

Rett syndrome (RTT) and Fragile X syndrome (FXS) are two monogenetic neurodevelopmental disorders with complex clinical presentations. RTT is caused by mutations in the Methyl-CpG binding protein 2 gene (MECP2) altering the function of its protein product MeCP2. MeCP2 modulates gene expression by binding methylated CpG dinucleotides, and by interacting with transcription factors. FXS is caused by the silencing of the FMR1 gene encoding the Fragile X Mental Retardation Protein (FMRP), a RNA binding protein involved in multiple steps of RNA metabolism, and modulating the translation of thousands of proteins including a large set of synaptic proteins. Despite differences in genetic etiology, there are overlapping features in RTT and FXS, possibly due to interactions between MeCP2 and FMRP, and to the regulation of pathways resulting in dysregulation of common molecular signaling. Furthermore, basic physiological mechanisms are regulated by these proteins and might concur to the pathophysiology of both syndromes. Considering that RTT and FXS are disorders affecting brain development, and that most of the common targets of MeCP2 and FMRP are involved in brain activity, we discuss the mechanisms of synaptic function and plasticity altered in RTT and FXS, and we consider the similarities and the differences between these two disorders.


Author(s):  
◽  
Rebecca Schira ◽  
Samantha Alexander ◽  
Noelani Brisbane ◽  
Kaitlyn Williams
Keyword(s):  

Author(s):  
Decerie Mendoza ◽  
Tracy Ye ◽  
Martina Dualan ◽  
Elena Javier
Keyword(s):  

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