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| Intellectual disability syndromic and non-syndromic v0.3128 | MPP5 | Zornitza Stark Marked gene: MPP5 as ready | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3128 | MPP5 | Zornitza Stark Gene: mpp5 has been classified as Green List (High Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3128 | MPP5 | Zornitza Stark Classified gene: MPP5 as Green List (high evidence) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3128 | MPP5 | Zornitza Stark Gene: mpp5 has been classified as Green List (High Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3127 | MPP5 |
Konstantinos Varvagiannis gene: MPP5 was added gene: MPP5 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: MPP5 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: MPP5 were set to 33073849 Phenotypes for gene: MPP5 were set to Global developmental delay; Intellectual disability; Delayed speech and language development; Developmental regression; Behavioral abnormality Penetrance for gene: MPP5 were set to unknown Review for gene: MPP5 was set to GREEN Added comment: Sterling et al (2020 - PMID: 33073849) provide information on the phenotype of 3 individuals with de novo MPP5 variants. Common features included global developmental delay, intellectual disability (3/3 - severe in 2/3), speech delay/regression (the latter in at least 2) and behavioral abnormalities. Variable other features were reported, among others microcephaly (1/3), abnormal vision (1/3 : CVI, retinal dystrophy, nystagmus), brain MRI abnormalities (2/3), late-onset seizures (1/3). These subjects displayed variable and non-specific dysmorphic features. All were investigated by exome sequencing (previous investigations not mentioned). One subject was found to harbor a de novo mosaic (5/25 reads) stopgain variant, further confirmed by Sanger sequencing [NM_022474.4:c.1555C>T - p.(Arg519Ter). The specific variant is reported once in gnomAD (1/251338). Two de novo missense variants were identified in the remaining individuals [c.1289A>G - p.Glu430Gly / c.974A>C - p.His325Pro). All variants had in silico predictions in favor of a deleterious effect (CADD score >24). The authors comment that MPP5 encodes an apical complex protein with asymmetric localization to the apical side of polarized cells. It is expressed in brain, peripheral nervous system and other tissues. MPP5 is a member of the membrane-associated guanylate kinase family of proteins (MAGUK p55 subfamily), determining cell polarity at tight junctions. Previous animal models suggest that complete Mpp5(Pals1) KO in mice leads to near absence of cerebral cortical neurons. Htz KO display reduction in size of cerebral cortex and hippocampus. The gene is expressed in proliferating cell populations of cerebellum and important for establishment cerebellar architecture. Conditional KO of Mpp5(Pals1) in retinal progenitor cells mimics the retinal pathology observed in LCA. [Several refs. provided] The authors studied a heterozygous CNS-specific Mpp5 KO mouse model. These mice presented microcephaly, decreased cerebellar volume and cortical thickness, decreased ependymal cells and Mpp5 at the apical surface of cortical vertrical zone. The proportion of cortical cells undergoing apoptotic cell death was increased. Mice displayed behavioral abnormalities (hyperactivity) and visual deficits, with ERG traces further suggesting retinal blindness. Overall the mouse model was thought to recapitulate the behavioral abnormalities observed in affected subjects as well as individual rare features such as microcephaly and abnormal vision. Haploinsufficiency (rather than a dominant negative effect) is favored as the underlying disease mechanism. This is also in line with a dose dependent effect observed in mice. Sources: Literature |
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