rs41412046
Variant summary
Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM2PP5_Very_Strong
The NM_000517.6(HBA2):c.429A>T(p.Ter143TyrextTer31) variant causes a stop lost change. The variant allele was found at a frequency of 0.0000067 in 149,166 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★).
Frequency
Genomes: 𝑓 0.0000067 ( 0 hom., cov: 25)
Consequence
HBA2
NM_000517.6 stop_lost
NM_000517.6 stop_lost
Scores
3
1
3
Clinical Significance
Conservation
PhyloP100: 4.93
Genes affected
HBA2 (HGNC:4824): (hemoglobin subunit alpha 2) The human alpha globin gene cluster located on chromosome 16 spans about 30 kb and includes seven loci: 5'- zeta - pseudozeta - mu - pseudoalpha-1 - alpha-2 - alpha-1 - theta - 3'. The alpha-2 (HBA2) and alpha-1 (HBA1) coding sequences are identical. These genes differ slightly over the 5' untranslated regions and the introns, but they differ significantly over the 3' untranslated regions. Two alpha chains plus two beta chains constitute HbA, which in normal adult life comprises about 97% of the total hemoglobin; alpha chains combine with delta chains to constitute HbA-2, which with HbF (fetal hemoglobin) makes up the remaining 3% of adult hemoglobin. Alpha thalassemias result from deletions of each of the alpha genes as well as deletions of both HBA2 and HBA1; some nondeletion alpha thalassemias have also been reported. [provided by RefSeq, Jul 2008]
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ACMG classification
Classification made for transcript
Verdict is Pathogenic. Variant got 10 ACMG points.
PM2
?
Very rare variant in population databases, with high coverage;
PP5
?
Variant 16-173600-A-T is Pathogenic according to our data. Variant chr16-173600-A-T is described in ClinVar as [Pathogenic]. Clinvar id is 15652.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | UniProt |
---|---|---|---|---|---|---|---|
HBA2 | NM_000517.6 | c.429A>T | p.Ter143TyrextTer31 | stop_lost | 3/3 | ENST00000251595.11 |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|
HBA2 | ENST00000251595.11 | c.429A>T | p.Ter143TyrextTer31 | stop_lost | 3/3 | 1 | NM_000517.6 | P1 | |
HBA2 | ENST00000482565.1 | n.565A>T | non_coding_transcript_exon_variant | 2/2 | 1 | ||||
ENST00000702607.1 | n.61T>A | non_coding_transcript_exon_variant | 1/1 | ||||||
HBA2 | ENST00000397806.1 | c.333A>T | p.Ter111TyrextTer31 | stop_lost | 3/3 | 2 |
Frequencies
GnomAD3 genomes ? AF: 0.00000671 AC: 1AN: 149044Hom.: 0 Cov.: 25
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GnomAD4 exome Cov.: 33
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GnomAD4 genome ? AF: 0.00000670 AC: 1AN: 149166Hom.: 0 Cov.: 25 AF XY: 0.0000137 AC XY: 1AN XY: 72872
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ClinVar
Significance: Pathogenic
Submissions summary: Pathogenic:5
Revision: criteria provided, multiple submitters, no conflicts
LINK: link
Submissions by phenotype
alpha Thalassemia Pathogenic:2
Pathogenic, no assertion criteria provided | clinical testing | Natera, Inc. | Dec 29, 2017 | - - |
Pathogenic, criteria provided, single submitter | clinical testing | Women's Health and Genetics/Laboratory Corporation of America, LabCorp | Aug 29, 2023 | Variant summary: HBA2 c.429A>T (p.X143TyrextX31) changes the termination codon and is predicted to lead to an extended protein with additional amino acids added to the normal C-terminus. This variant is also known as Hb Pakse. Four other extensions variants disrupting this termination codon have been classified as pathogenic/likely pathogenic by ClinVar submitters. The variant was absent in 248852 control chromosomes (gnomAD). c.429A>T has been reported in the literature in multiple individuals affected with Alpha Thalassemia who were compound heterozygous with other pathogenic variants (Waye_1994, Sanchaisuriya_2002, Pornprasert_2012). These data indicate that the variant is very likely to be associated with disease. The following publications have been ascertained in the context of this evaluation (PMID: 8193381, 22881835, 12403487). Three submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. - |
not provided Pathogenic:2
Pathogenic, criteria provided, single submitter | clinical testing | Quest Diagnostics Nichols Institute San Juan Capistrano | Sep 19, 2023 | The HBA2 c.429A>T (p.*143Tyrext*31) variant, also known as Hb Pakse, disrupts the translation stop codon of the HBA2 mRNA and is predicted to cause HBA2 protein elongation. This variant has been reported in the published literature in individuals compound heterozygous with the SEA alpha-1 deletion affected with Hb H disease (PMIDs: 8193381 (1994), 11836160 (2002)) and individuals compound heterozygous with Hb Adana (PMID: 27271331 (2016)) and Hb Constant Spring affected with alpha-thalassemia (PMIDs: 21077767 (2010), 27271331 (2016), 28244614 (2018), 30615015 (2019)). This variant has not been reported in large, multi-ethnic general populations (Genome Aggregation Database, http://gnomad.broadinstitute.org). Based on the available information, this variant is classified as pathogenic. - |
Pathogenic, criteria provided, single submitter | clinical testing | ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories | Oct 05, 2023 | The Hb Pakse variant (HBA2: c.429A>T; p.Ter143Tyr, also known as Ter142Tyr when numbered from the mature protein, rs41412046. HbVar ID: 707) has been described in multiple individuals with alpha-thalassemia (Nguyen 2014, Pichanun 2010, Waye 1994, HbVar database). Hb Pakse is one of the most prevalent non-deletion alpha-thalassemias in Southeast Asia (Singsanan 2007). This variant is listed in ClinVar (Variation ID: 15652), and is absent from the Genome Aggregation Database, indicating it is not a common polymorphism. This variant altered the canonical termination codon, and creates elongated, unstable mRNA that results in reduced alpha-chain synthesis (Waye 1994). Based on available information, the Hb Pakse variant is considered to be pathogenic. References: Link to HbVar database: https://globin.bx.psu.edu/hbvar/menu.html Nguyen et al. Hemoglobin Constant Spring is markedly high in women of an ethnic minority group in Vietnam: a community-based survey and hematologic features. Blood Cells Mol Dis. 2014; 52(4):161-5. PMID: 24368026. Pichanun et al. Molecular screening of the Hbs Constant Spring (codon 142, TAA>CAA, alpha2) and Pakse (codon 142, TAA>TAT, alpha2) mutations in Thailand. Hemoglobin. 2010; 34(6):582-6. PMID: 21077767. Singsanan et al. Molecular characterization and origins of Hb Constant Spring and Hb Pakse in Southeast Asian populations. Ann Hematol. 2007; 86(9):665-9. PMID: 17589844. Waye et al. Identification of a novel termination codon mutation (TAA-->TAT, Term-->Tyr) in the alpha 2 globin gene of a Laotian girl with hemoglobin H disease. Blood. 1994; 83(11):3418-20. PMID: 8193381. - |
Hemoglobin H disease, nondeletional Pathogenic:1
Pathogenic, no assertion criteria provided | literature only | OMIM | Jun 01, 1994 | - - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
BayesDel_addAF
Uncertain
D
BayesDel_noAF
Benign
Cadd
Benign
Dann
Benign
Eigen
Pathogenic
Eigen_PC
Pathogenic
FATHMM_MKL
Pathogenic
D
MutationTaster
Benign
N;N
Vest4
GERP RS
RBP_binding_hub_radar
RBP_regulation_power_radar
Splicing
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Calibrated prediction
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SpliceAI score (max)
Details are displayed if max score is > 0.2
Find out detailed SpliceAI scores and Pangolin per-transcript scores at