1-158685289-C-T
Variant summary
Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1PM5PP3_StrongPP5_Very_Strong
The NM_003126.4(SPTA1):c.83G>A(p.Arg28His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000112 in 1,613,892 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R28C) has been classified as Pathogenic.
Frequency
Consequence
NM_003126.4 missense
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Pathogenic. Variant got 16 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000789 AC: 12AN: 152116Hom.: 0 Cov.: 32
GnomAD3 exomes AF: 0.0000122 AC: 3AN: 246770Hom.: 0 AF XY: 0.00000746 AC XY: 1AN XY: 134086
GnomAD4 exome AF: 0.00000410 AC: 6AN: 1461658Hom.: 0 Cov.: 66 AF XY: 0.00000413 AC XY: 3AN XY: 727138
GnomAD4 genome AF: 0.0000788 AC: 12AN: 152234Hom.: 0 Cov.: 32 AF XY: 0.0000672 AC XY: 5AN XY: 74430
ClinVar
Submissions by phenotype
not provided Pathogenic:5
This sequence change replaces arginine, which is basic and polar, with histidine, which is basic and polar, at codon 28 of the SPTA1 protein (p.Arg28His). This variant is present in population databases (rs121918641, gnomAD 0.02%). This missense change has been observed in individual(s) with elliptocytosis and/or pyropoikilocytosis (PMID: 1679439, 2328319). It has also been observed to segregate with disease in related individuals. This variant is also known as p.Arg22His. ClinVar contains an entry for this variant (Variation ID: 12856). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed for this missense variant. However, the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on SPTA1 protein function. Experimental studies have shown that this missense change affects SPTA1 function (PMID: 18218854). This variant disrupts the p.Arg28 amino acid residue in SPTA1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 1679439, 18218854, 28090778, 29729090, 31286676). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -
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Functional characterization of protein harboring the R28H variant indicate no detectable binding affinity to the beta subunit, thus abolishing tetramer formation (PMID: 18218854); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Also known as p.R22H; This variant is associated with the following publications: (PMID: 2043465, 3692477, 28102861, 29936674, 30317022, 1679439, 7819065, 27667160, 31723846, 31038472, 33210974, 10680706, 31589614, 31694722, 33074480, 33726816, 34132406, 2328319, 18218854, 7074218, 8435324, 28090778, 29729090) -
The SPTA1 c.83G>A; p.Arg28His variant (rs121918641), also known as p.Arg22His, is reported in the literature in at least 12 individuals from a multigenerational family affected with either elliptocytosis or pyropoikilocytosis (Garbarz 1990). It has also been reported on opposite chromosomes from the complex alpha-LELY allele in one individual with severe elliptocytosis (Baklouti 1991), as well as five individuals affected with elliptocytosis and pyropoikilocytosis from two unrelated families (Coetzer 1991). In vitro functional analyses show this variant abrogates spectrin tetramerization (Gaetani 2008). This variant is reported in ClinVar (Variation ID: 12856) and is found predominantly in the African/African-American population with an allele frequency of 0.03% (7/24,196 alleles) in the Genome Aggregation Database. Additionally, other amino acid substitutions at this codon (p.Arg28Leu, p.Arg28Ser, and p.Arg28Cys) have been reported in individuals with elliptocytosis and are considered pathogenic (Coetzer 1991, Floyd 1991). Computational analyses are uncertain whether this variant is neutral or deleterious (REVEL: 0.419). Based on available information, this variant is considered to be pathogenic. References: Baklouti F et al. Occurrence of the alpha I 22 Arg----His (CGT----CAT) spectrin mutation in Tunisia: potential association with severe elliptopoikilocytosis. Br J Haematol. 1991 May. PMID: 2043465. Coetzer TL et al. Four different mutations in codon 28 of alpha spectrin are associated with structurally and functionally abnormal spectrin alpha I/74 in hereditary elliptocytosis. J Clin Invest. 1991 Sep. PMID: 1679439. Floyd PB et al. Heterogeneity of the molecular basis of hereditary pyropoikilocytosis and hereditary elliptocytosis associated with increased levels of the spectrin alpha I/74-kilodalton tryptic peptide. Blood. 1991 Sep 01. PMID: 1878597. Gaetani M et al. Structural and functional effects of hereditary hemolytic anemia-associated point mutations in the alpha spectrin tetramer site. Blood. 2008 Jun 15. PMID: 18218854. Garbarz M et al. Hereditary pyropoikilocytosis and elliptocytosis in a white French family with the spectrin alpha I/74 variant related to a CGT to CAT codon change (Arg to His) at position 22 of the spectrin alpha I domain. Blood. 1990 Apr 15. PMID: 2328319. -
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Elliptocytosis 2 Pathogenic:3
ACMG classification criteria: PS3 supporting, PM5 moderated, PM6 moderated, PP1 strong -
The c.83G>A (p.Arg28His) missense variant (published as R22H due to alternate nomenclature) in SPTA1 gene has been reported previously in a multigenerational family with either hereditary elliptocytosis (HE) or hereditary pyropoikilocytosis (Garbarz et al., 1990). Functional characterization of protein harboring the R28H variant indicate no detectable binding affinity to the beta subunit, thus abolishing tetramer formation (Gaetani et al., 2008). This variant is reported with the allele frequency (0.001%) in the gnomAD and novel in 1000 genome database. This variant has been reported to the ClinVar database as Pathogenic. The amino acid Arg at position 28 is changed to a His changing protein sequence and it might alter its composition and physico-chemical properties. The amino acid change p.Arg28His in SPTA1 is predicted as conserved by GERP++ and PhyloP across 100 vertebrates. For these reasons, this variant has been classified as Pathogenic. -
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Pyropoikilocytosis, hereditary Pathogenic:2
The variant is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: 0.003%). Functional studies provide strong evidence of the variant having a damaging effect on the gene or gene product (PMID: 18218854). In silico tool predictions suggest damaging effect of the variant on gene or gene product (3Cnet: 0.85). Same nucleotide change resulting in same amino acid change has been previously reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000012856). Different missense changes at the same codon (p.Arg28Cys, p.Arg28Leu) have been reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000012853, VCV000012855). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -
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Prenatal anemia Pathogenic:1
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SPTA1-related disorder Pathogenic:1
The SPTA1 c.83G>A variant is predicted to result in the amino acid substitution p.Arg28His. This variant along with other missense changes at the same amino acid position (p.Arg28Leu and p.Arg28Cys) have been shown to be causative for hereditary elliptocytosis in the heterozygous state (Garbarz et al. 1990. PubMed ID: 2328319; Coetzer et al. 1991. PubMed ID: 1679439). This variant is reported in 0.029% of alleles in individuals of African descent in gnomAD. This variant is interpreted as pathogenic. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at