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| Intellectual disability - microarray and sequencing v4.53 | CHKA | Arina Puzriakova Tag Q3_22_rating was removed from gene: CHKA. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v4.53 | CHKA | Arina Puzriakova reviewed gene: CHKA: Rating: GREEN; Mode of pathogenicity: ; Publications: ; Phenotypes: ; Mode of inheritance: | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v4.52 | CHKA |
Arina Puzriakova Source NHS GMS was added to CHKA. Source Expert Review Green was added to CHKA. Rating Changed from Amber List (moderate evidence) to Green List (high evidence) |
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| Intellectual disability - microarray and sequencing v3.1742 | CHKA | Eleanor Williams commented on gene: CHKA | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v3.1742 | CHKA | Eleanor Williams Tag Q3_22_MOI was removed from gene: CHKA. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v3.1679 | CHKA |
Sarah Leigh Tag Q3_22_rating tag was added to gene: CHKA. Tag Q3_22_MOI tag was added to gene: CHKA. |
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| Intellectual disability - microarray and sequencing v3.1679 | CHKA |
Sarah Leigh edited their review of gene: CHKA: Added comment: Not associated with a phenotype in OMIM, Gen2Phen or MONDO. PMID: 35202461 reports five CHKA variants in five unrelated cases with a neurodevelopmental disorder, which includes intellectual disability, epileptic encephalopathy and severe microcephaly (PMID: 35202461). Suportive functional studies are also presented in this article.; Changed rating: GREEN |
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| Intellectual disability - microarray and sequencing v3.1679 | CHKA | Sarah Leigh Classified gene: CHKA as Amber List (moderate evidence) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v3.1679 | CHKA | Sarah Leigh Added comment: Comment on list classification: There is enough evidence for this gene to be rated GREEN at the next major review. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v3.1679 | CHKA | Sarah Leigh Gene: chka has been classified as Amber List (Moderate Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v3.1500 | CHKA |
Konstantinos Varvagiannis gene: CHKA was added gene: CHKA was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: CHKA was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: CHKA were set to 35202461 Phenotypes for gene: CHKA were set to Abnormal muscle tone; Global developmental delay; Intellectual disability; Seizures; Microcephaly; Abnormality of movement; Abnormality of nervous system morphology; Short stature Penetrance for gene: CHKA were set to Complete Review for gene: CHKA was set to GREEN Added comment: Klöckner (2022 - PMID: 35202461) describe the phenotype of 6 individuals (from 5 unrelated families) harboring biallelic CHKA variants. Shared features incl. abnormal muscle tone(6/6 - hypertonia or hypotonia, 3/6 each), DD/ID (6/6,severe in 4, severe/profound in 2), epilepsy (6/6 - onset: infancy - 3y2m | epileptic spasms or GS at onset), microcephaly (6/6), movement disorders (3/6 - incl. dyskinesia, rigidity, choreoatetotic movements). 2/5 individuals exhibited MRI abnormalities, notably hypomyelination. Short stature was observed in 4/6. Eventual previous genetic testing was not discussed. Exome sequencing (quattro ES for 2 sibs, trio ES for 1 individual, singleton for 3 probands) revealed biallelic CHKA variants in all affected individuals. Sanger sequencing was performed for confirmation and segregation studies. Other variants (in suppl.) were not deemed to be causative for the neurodevelopmental phenotype. 3 different missense, 1 start-loss and 1 truncating variant were identified, namely (NM_0012772.2): - c.421C>T/p.(Arg141Trp) [3 hmz subjects from 2 consanguineous families], - c.580C>T/p.Pro194Ser [1 hmz individual born to consanguineous parents], - c.2T>C/p.(Met1?) [1 hmz individual born to related parents], - c.14dup/p.(Cys6Leufs*19) in trans with c.1021T>C/p.(Phe341Leu) in 1 individual. CHKA encodes choline kinase alpha, an enzyme catalyzing the first step of phospholipid synthesis in the Kennedy pathway. The pathway is involved in de novo synthesis of glycerophospholipids, phosphatidylcholine and phosphatidylethanolamine being the most abundant in eukaryotic membranes. CHKA with its paralog (CHKB) phosphorylates either choline or ethanolamine to phosphocholine or phosphoethanolamine respectively with conversion of ATP to ADP. As the authors comment, biallelic pathogenic variants in CHKB cause a NDD with muscular dystrophy, hypotonia, ID, microcephaly and structural mitochondrial anomalies (MIM 602541). [Prominent mitochondrial patterning was observed in a single muscle biopsy available from an individual with biallelic CHKA variants]. Other disorders of the Kennedy pathway (due to biallelic PCYT2, SELENOI, PCYT1A variants) present with overlapping features incl. variable DD/ID (no-severe), microcephaly, seizures, visual impairment etc. CHKA variants were either absent or observed once in gnomAD, affected highly conserved AAs with multiple in silico predictions in favor of a deleterious effect. In silico modeling suggests structural effects for several of the missense variants (Arg141Trp, Pro194Ser presumably affect ADP binding, Phe341 lying close to the binding site of phosphocholine). Each of the missense variants was expressed in yeast cells and W. Blot suggested expression at the expected molecular weight at comparative levels. The 3 aforementioned variants exhibited reduced catalytic activity (20%, 15%, 50% respectively). NMD is thought to underly the deleterious effect of the frameshift one (not studied). The start-loss variant is expected to result in significantly impaired expression and protein function as eventual utilization of the next possible start codon - occurring at position 123 - would remove 26% of the protein. Chka(-/-) is embryonically lethal in mice, suggesting that complete loss is not compatible with life. Reduction of choline kinase activity by 30% in heterozygous mice did not appear to result in behavioral abnormalities although this was not studied in detail (PMID cited: 18029352). Finally, screening of 1566 mouse lines identified 198 genes whose disruption yields neuroanatomical phenotypes, Chka(+/-) mice being among these (PMID cited: 31371714). There is no associated phenotype in OMIM, Gene2Phenotype or SysID. Overall this gene can be considered for inclusion in the ID and epilepsy panes with green or amber rating (>3 individuals, >3 variants, variant studies, overlapping phenotype of disorders belonging to the same pathway, etc). Consider also inclusion in the microcephaly panel (where available this seemed to be of postnatal onset). Sources: Literature |
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