rs34889882
Variant summary
Our verdict is Pathogenic. The variant received 15 ACMG points: 16P and 1B. PVS1PP5_Very_StrongBS2_Supporting
The NM_000518.5(HBB):c.17_18delCT(p.Pro6ArgfsTer17) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000236 in 1,611,036 control chromosomes in the GnomAD database, including 2 homozygotes. Variant has been reported in ClinVar as Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. P6P) has been classified as Likely benign.
Frequency
Consequence
NM_000518.5 frameshift
Scores
Clinical Significance
Conservation
Publications
- dominant beta-thalassemiaInheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), ClinGen
- hemoglobin M diseaseInheritance: AD Classification: DEFINITIVE, MODERATE, SUPPORTIVE Submitted by: Orphanet, Ambry Genetics, ClinGen
- beta thalassemiaInheritance: AR Classification: DEFINITIVE Submitted by: Myriad Women’s Health
- beta-thalassemia HBB/LCRBInheritance: AR, SD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, Ambry Genetics
- sickle cell disease and related diseasesInheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
- erythrocytosis, familial, 6Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp
- Heinz body anemiaInheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
- sickle cell diseaseInheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae)
- hereditary persistence of fetal hemoglobin-beta-thalassemia syndromeInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- beta-thalassemia intermediaInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- beta-thalassemia majorInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- delta-beta-thalassemiaInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- hemoglobin C diseaseInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- hemoglobin C-beta-thalassemia syndromeInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- hemoglobin E diseaseInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- hemoglobin E-beta-thalassemia syndromeInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- hereditary persistence of fetal hemoglobin-sickle cell disease syndromeInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- sickle cell-beta-thalassemia disease syndromeInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- sickle cell-hemoglobin c disease syndromeInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- sickle cell-hemoglobin d disease syndromeInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- sickle cell-hemoglobin E disease syndromeInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
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ACMG classification
Our verdict: Pathogenic. The variant received 15 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000394 AC: 6AN: 152216Hom.: 2 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.0000438 AC: 11AN: 251156 AF XY: 0.0000516 show subpopulations
GnomAD4 exome AF: 0.0000219 AC: 32AN: 1458702Hom.: 0 AF XY: 0.0000303 AC XY: 22AN XY: 725878 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.0000394 AC: 6AN: 152334Hom.: 2 Cov.: 32 AF XY: 0.0000537 AC XY: 4AN XY: 74508 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
not provided Pathogenic:6
The HBB c.17_18delCT; p.Pro6ArgfsTer17 variant (rs34889882, HbVarID: 783), also known as Codon 5 (-CT) or Pro5fs when numbered from the mature protein, has been reported in the literature in an individual with beta(0) thalassemia (Kollia 1989, HbVar database and references therein). This variant is reported as pathogenic in ClinVar (Variation ID: 15422). It is found in the general population with an overall allele frequency of 0.004% (11/251156 alleles) in the Genome Aggregation Database. This variant causes a frameshift by deleting 2 nucleotides, so it is predicted to result in a truncated protein or mRNA subject to nonsense-mediated decay. Based on available information, this variant is considered to be pathogenic. References: Link to HbVar database: https://globin.bx.psu.edu/hbvar/menu.html Kollia et al. Frameshift codon 5 (Fsc-5 (-CT)) thalassemia; a novel mutation detected in a Greek patient. Hemoglobin. 1989;13(6):597-604. PMID: 2606727. -
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The HBB c.17_18del (p.Pro6Argfs*17) variant (also known as CD5 (-CT)) alters the translational reading frame of the HBB mRNA and causes the premature termination of HBB protein synthesis. In the published literature, this variant has been reported in the compound heterozygous and homozygous state in individuals with beta-thalassemia major and intermedia (PMIDs: 33491330 (2021), 27263053 (2016), 25617386 (2015), 2606727 (1989)). Based on the available information, this variant is classified as pathogenic. -
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This sequence change creates a premature translational stop signal (p.Pro6Argfs*17) in the HBB gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in HBB are known to be pathogenic (PMID: 23637309). This variant is present in population databases (rs34889882, gnomAD 0.04%). This premature translational stop signal has been observed in individual(s) with beta thalassemia (PMID: 2606727). This variant is also known as Pro5fs and FSC-5(-CT). ClinVar contains an entry for this variant (Variation ID: 15422). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
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beta Thalassemia Pathogenic:5
Variant summary: The HBB c.17_18delCT is a frame-shift variant resulting in termination of translation at codon 23, which is predicted to cause either a truncated or absent HBB protein through non-sense mediated decay which is a commonly known mechanism for BTHAL. Truncations downstream of this position have been classified as pathogenic by our laboratory (e.g. p.Leu29fs). This variant is found in 1/121340 control chromosomes from ExAC at a frequency of 0.0000082, which does not exceed the maximal expected frequency of a pathogenic allele (0.0111803) in this gene. This variant has been commonly identified in beta-thalassemia patients in both compound heterozygous and homozygous states. It is also reported as one of the common mutations in Middle Eastern countries (Lahiry_2008). Taken together, this variant has been classified as a disease variant/pathogenic. -
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The p.Pro6ArgfsX17 variant in HBB has been reported in several individuals with beta thalassemia and is one of the common pathogenic variants in Middle Eastern countries ( selected references Kollia 1989 PMID: 2606727, Vetter 1997 PMID: 9163586, Murad 2021 PMID: 33491330). It has also been reported in ClinVar (Variation ID 15422) and was identified in 6/4834 South Asian chromosomes by gnomAD (https://gnomad.broadinstitute.org). This variant is predicted to cause a frameshift, which alters the protein’s amino acid sequence beginning at position 6 and leads to a premature termination codon 17 amino acids downstream. This alteration is then predicted to lead to a truncated or absent protein. Loss of function of the HBB gene is an established disease mechanism in autosomal recessive beta thalassemia. In summary, this variant meets criteria to be classified as pathogenic for autosomal recessive beta thalassemia. ACMG/AMP Criteria applied: PM2_Supporting, PVS1, PM3_Strong. -
Beta-thalassemia HBB/LCRB Pathogenic:4
This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -
The variant is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: 0.004%). Predicted Consequence/Location: Frameshift: predicted to result in a loss or disruption of normal protein function through nonsense-mediated decay (NMD) or protein truncation. Multiple pathogenic variants are reported downstream of the variant. The variant has been reported at least twice as pathogenic with clinical assertions and evidence for the classification (ClinVar ID: VCV000015422 /PMID: 2606727). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -
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The HBB c.17_18delCT (NP_000509.1:p.Pro6fs ) is a frame-shift variant, which is also a beta 0 mutation. When this variant present with other pathogenic HBB mutation leads to severe type of thalassemia. Patients needing blood transfusion, often presented with hepatosplenomegaly, Iron overload. The frequency of the variant among thalassemia patient in Eastern India is 0.19 % as per our multicentric project - A Genetic Diagnostic Algorithm Based Study for Thalassemia in Northern and Eastern Indian Populations, Funded by Dept. of Biotechnology , Govt of India [Project No. BT/PR26461/MED/12/821/2018] -
Dominant beta-thalassemia Pathogenic:1
Criteria applied: PVS1,PS4,PM2_SUP -
Beta zero thalassemia Pathogenic:1
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HBB-related disorder Pathogenic:1
The HBB c.17_18delCT variant is predicted to result in a frameshift and premature protein termination (p.Pro6Argfs*17). This variant is also known as Codon 5 [-CT], FSC-5(-CT), or CD 5 -CT in the literature. This variant was reported in the homozygous and compound heterozygous states to be causative for autosomal recessive beta-thalassemia (Kollia et al. 1989. PubMed ID: 2606727; Elmezayen et al. 2015. PubMed ID: 25617386; Murad et al. 2021. PubMed ID: 33491330). This variant is reported in 0.036% of alleles in individuals of South Asian descent in gnomAD. Frameshift variants in HBB are expected to be pathogenic. This variant is interpreted as pathogenic. -
Hb SS disease;C0019025:Hereditary persistence of fetal hemoglobin;C0700299:Heinz body anemia;C1840779:METHEMOGLOBINEMIA, BETA TYPE;C1858990:Dominant beta-thalassemia;C1970028:Malaria, susceptibility to;C4693822:Erythrocytosis, familial, 6;CN322236:Beta-thalassemia HBB/LCRB Pathogenic:1
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Hb SS disease Pathogenic:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at