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| Intellectual disability syndromic and non-syndromic v0.4939 | PTPA |
Konstantinos Varvagiannis changed review comment from: Biallelic PTPA pathogenic variants lead to a form of ID with later-onset parkinsonism based on 4 individuals from 2 families in the literature. Affected individuals were homozygous for missense variants demonstrated to result to reduced mRNA and protein levels as well as PP2A complex activation. Drosophila studies support an age-dependent locomotor dysfunction. Variants in other PP2A-complex-related genes also lead to NDDs. Summary provided below. There is currently no associated phenotype in OMIM, G2P, PanelApp Australia or SysID. Consider inclusion in relevant panels (ID, Parkinsonism/movement disorders, etc) with amber rating pending further reports. ------ Fevga, Tesson et al (2022 - PMID: 36073231) describe the features of 4 individuals, from 2 unrelated families, with biallelic pathogenic PTPA variants. These presented with normal or delayed early milestones, learning disability and ID (mild to moderate) followed by progressive signs of parkinsonism (at the age of 11 yrs in 2 sibs, 15 yrs in another individual). Motor symptoms were responsive to levodopa and later to deep brain stimulation. Linkage analysis in one consanguineous family followed by exome revealed homozygosity for a missense PTPA variant (NM_178001:c.893T>G/p.Met298Arg). Exome sequencing in affected subjects from the 2nd family revealed homozygosity for a further missense variant (c.512C>A/p.Ala171Asp). There were no other candidate variants for the phenotype following parental / segregation studies. Role of the gene: As the authors discuss, PTPA (or PPP2R4) is ubiquitously expressed in all tissues incl. brain and encodes a phosphotyrosyl phosphatase activator of the dimeric form of protein phosphatase-2A (PP2A). PP2A in turn, is the major Ser/Thr phosphatase in brain targeting a large number of proteins involved in diverse functions. Activation of PP2A is dependent on its methylation, which is negatively regulated by the PP2A-specific methylesterase (PME-1). By binding to PME-1, PTPA counteracts the negative influence of the former on PP2A. Pathogenic variants in genes encoding subunits/regulators of the PP2A complex (e.g. PPP2R1A or PPP2CA) are associated with neurodevelopmental disorders. Variant studies: Upon overexpression of wt and both variants in a HEK-293 cell line the authors demonstrated that both variants resulted in significantly reduced mRNA and protein levels (which for Ala171Asp were attributed to increased proteasomal degradation). Both variants were shown to result in impaired PP2A complex activation compared to wt. Drosophila / animal models: Pan-neuronal RNAi-mediated knockdown of ptpa in Drosophila resulted in an age-dependent locomotor dysfunction, reversible with L-DOPA treatment. Previous studies in mice suggest cognitive/electrophysiological impairments upon downregulation of PP2A activity in transgenic mice. Sources: Literature; to: Biallelic PTPA pathogenic variants lead to a form of ID with later-onset parkinsonism based on 4 individuals from 2 families in the literature. Affected individuals were homozygous for missense variants demonstrated to result to reduced mRNA and protein levels as well as PP2A complex activation. Drosophila studies support an age-dependent locomotor dysfunction. Variants in other PP2A-complex-related genes also lead to NDDs. Summary provided below. There is currently no associated phenotype in OMIM, G2P, PanelApp UK or SysID. Consider inclusion in relevant panels (ID, Parkinsonism/movement disorders, etc) with amber rating pending further reports. ------ Fevga, Tesson et al (2022 - PMID: 36073231) describe the features of 4 individuals, from 2 unrelated families, with biallelic pathogenic PTPA variants. These presented with normal or delayed early milestones, learning disability and ID (mild to moderate) followed by progressive signs of parkinsonism (at the age of 11 yrs in 2 sibs, 15 yrs in another individual). Motor symptoms were responsive to levodopa and later to deep brain stimulation. Linkage analysis in one consanguineous family followed by exome revealed homozygosity for a missense PTPA variant (NM_178001:c.893T>G/p.Met298Arg). Exome sequencing in affected subjects from the 2nd family revealed homozygosity for a further missense variant (c.512C>A/p.Ala171Asp). There were no other candidate variants for the phenotype following parental / segregation studies. Role of the gene: As the authors discuss, PTPA (or PPP2R4) is ubiquitously expressed in all tissues incl. brain and encodes a phosphotyrosyl phosphatase activator of the dimeric form of protein phosphatase-2A (PP2A). PP2A in turn, is the major Ser/Thr phosphatase in brain targeting a large number of proteins involved in diverse functions. Activation of PP2A is dependent on its methylation, which is negatively regulated by the PP2A-specific methylesterase (PME-1). By binding to PME-1, PTPA counteracts the negative influence of the former on PP2A. Pathogenic variants in genes encoding subunits/regulators of the PP2A complex (e.g. PPP2R1A or PPP2CA) are associated with neurodevelopmental disorders. Variant studies: Upon overexpression of wt and both variants in a HEK-293 cell line the authors demonstrated that both variants resulted in significantly reduced mRNA and protein levels (which for Ala171Asp were attributed to increased proteasomal degradation). Both variants were shown to result in impaired PP2A complex activation compared to wt. Drosophila / animal models: Pan-neuronal RNAi-mediated knockdown of ptpa in Drosophila resulted in an age-dependent locomotor dysfunction, reversible with L-DOPA treatment. Previous studies in mice suggest cognitive/electrophysiological impairments upon downregulation of PP2A activity in transgenic mice. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.4939 | PTPA |
Konstantinos Varvagiannis gene: PTPA was added gene: PTPA was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: PTPA was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: PTPA were set to 36073231 Phenotypes for gene: PTPA were set to Intellectual disability; Parkinsonism Penetrance for gene: PTPA were set to Complete Review for gene: PTPA was set to AMBER Added comment: Biallelic PTPA pathogenic variants lead to a form of ID with later-onset parkinsonism based on 4 individuals from 2 families in the literature. Affected individuals were homozygous for missense variants demonstrated to result to reduced mRNA and protein levels as well as PP2A complex activation. Drosophila studies support an age-dependent locomotor dysfunction. Variants in other PP2A-complex-related genes also lead to NDDs. Summary provided below. There is currently no associated phenotype in OMIM, G2P, PanelApp Australia or SysID. Consider inclusion in relevant panels (ID, Parkinsonism/movement disorders, etc) with amber rating pending further reports. ------ Fevga, Tesson et al (2022 - PMID: 36073231) describe the features of 4 individuals, from 2 unrelated families, with biallelic pathogenic PTPA variants. These presented with normal or delayed early milestones, learning disability and ID (mild to moderate) followed by progressive signs of parkinsonism (at the age of 11 yrs in 2 sibs, 15 yrs in another individual). Motor symptoms were responsive to levodopa and later to deep brain stimulation. Linkage analysis in one consanguineous family followed by exome revealed homozygosity for a missense PTPA variant (NM_178001:c.893T>G/p.Met298Arg). Exome sequencing in affected subjects from the 2nd family revealed homozygosity for a further missense variant (c.512C>A/p.Ala171Asp). There were no other candidate variants for the phenotype following parental / segregation studies. Role of the gene: As the authors discuss, PTPA (or PPP2R4) is ubiquitously expressed in all tissues incl. brain and encodes a phosphotyrosyl phosphatase activator of the dimeric form of protein phosphatase-2A (PP2A). PP2A in turn, is the major Ser/Thr phosphatase in brain targeting a large number of proteins involved in diverse functions. Activation of PP2A is dependent on its methylation, which is negatively regulated by the PP2A-specific methylesterase (PME-1). By binding to PME-1, PTPA counteracts the negative influence of the former on PP2A. Pathogenic variants in genes encoding subunits/regulators of the PP2A complex (e.g. PPP2R1A or PPP2CA) are associated with neurodevelopmental disorders. Variant studies: Upon overexpression of wt and both variants in a HEK-293 cell line the authors demonstrated that both variants resulted in significantly reduced mRNA and protein levels (which for Ala171Asp were attributed to increased proteasomal degradation). Both variants were shown to result in impaired PP2A complex activation compared to wt. Drosophila / animal models: Pan-neuronal RNAi-mediated knockdown of ptpa in Drosophila resulted in an age-dependent locomotor dysfunction, reversible with L-DOPA treatment. Previous studies in mice suggest cognitive/electrophysiological impairments upon downregulation of PP2A activity in transgenic mice. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.1558 | PPP2CA | Zornitza Stark Marked gene: PPP2CA as ready | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.1558 | PPP2CA | Zornitza Stark Gene: ppp2ca has been classified as Green List (High Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.1314 | PPP2CA | Chirag Patel Classified gene: PPP2CA as Green List (high evidence) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.1314 | PPP2CA | Chirag Patel Gene: ppp2ca has been classified as Green List (High Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.1313 | PPP2CA |
Chirag Patel gene: PPP2CA was added gene: PPP2CA was added to Intellectual disability, syndromic and non-syndromic_GHQ_VCGS. Sources: Literature Mode of inheritance for gene: PPP2CA was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: PPP2CA were set to PMID: 30595372 Phenotypes for gene: PPP2CA were set to Neurodevelopmental disorder and language delay with or without structural brain abnormalities; OMIM #618354 Review for gene: PPP2CA was set to GREEN Added comment: 15 unrelated patients with a neurodevelopmental disorder with de novo heterozygous PPP2CA mutations, and 1 with partial deletion of PPP2CA. Functional studies showed complete PP2A dysfunction in 4 individuals with seemingly milder ID, hinting at haploinsufficiency. Ten other individuals showed mutation-specific biochemical distortions, including poor expression, altered binding to the A subunit and specific B-type subunits, and impaired phosphatase activity and C-terminal methylation. Sources: Literature |
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