rs193922554

Variant names:

• chr11-5226687-GCA-G
• rs34282684
• NM_000518.5:c.203_204delTG

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000518.5(HBB):​c.203_204delTG​(p.Val68AlafsTer5) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: HBB NM_000518.5 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: 8.60

Genes affected

HBB (HGNC:4827): (hemoglobin subunit beta) The alpha (HBA) and beta (HBB) loci determine the structure of the 2 types of polypeptide chains in adult hemoglobin, Hb A. The normal adult hemoglobin tetramer consists of two alpha chains and two beta chains. Mutant beta globin causes sickle cell anemia. Absence of beta chain causes beta-zero-thalassemia. Reduced amounts of detectable beta globin causes beta-plus-thalassemia. The order of the genes in the beta-globin cluster is 5'-epsilon -- gamma-G -- gamma-A -- delta -- beta--3'. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most 50 bp of the penultimate exon, not predicted to undergo nonsense mediated mRNA decay. There are 89 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-5226687-GCA-G is Pathogenic according to our data. Variant chr11-5226687-GCA-G is described in ClinVar as [Pathogenic]. Clinvar id is 36303.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-5226687-GCA-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HBB	NM_000518.5	c.203_204delTG	p.Val68AlafsTer5	frameshift_variant	Exon 2 of 3	ENST00000335295.4	NP_000509.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HBB	ENST00000335295.4	c.203_204delTG	p.Val68AlafsTer5	frameshift_variant	Exon 2 of 3	1	NM_000518.5	ENSP00000333994.3

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:5

Aug 12, 2021

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The HBB c.203_204del (p.Val68Alafs*5) variant alters the translational reading frame of the HBB mRNA and causes the premature termination of HBB protein synthesis. This variant is associated with beta(0)-thalassemia (PMID: 8257991 (1993)). Previous names for this variant include Codon 67 (-TG). Based on the available information, this variant is classified as pathogenic. -

Dec 24, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Val68Alafs*5) 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 not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with beta thalassemia (PMID: 8257991). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 36303). For these reasons, this variant has been classified as Pathogenic. -

Jul 24, 2024

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 8257991, 27756326) -

Jul 15, 2024

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The HBB c.203_204delTG; p.Val68AlafsTer5 variant (rs34282684, HbVar ID: 868), also known as Codon 67 (-TG), is reported in the literature in an individual with beta-thalassemia major in trans to a whole-gene HBB deletion (Eng 1993). The c.203_204delTG variant was also observed in heterozygous relatives with hematological profiles consistent with beta-thalassemia minor (Eng 1993). This variant is reported in ClinVar (Variation ID: 36303) and is absent from the Genome Aggregation Database, indicating it is not a common polymorphism. This variant causes a frameshift by deleting two 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 Eng B et al. Identification of two novel beta zero-thalassemia mutations in a Filipino family: frameshift codon 67 (-TG) and a beta-globin gene deletion. Hum Mutat. 1993;2(5):375-9. PMID: 8257991 -

Jan 23, 2018

Clinical Genetics and Genomics, Karolinska University Hospital

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

beta Thalassemia Pathogenic:2

Oct 02, 2024

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: HBB c.203_204delTG (p.Val68AlafsX5) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. The frequency data for this variant in gnomAD is considered unreliable, as metrics indicate poor data quality at this position. c.203_204delTG has been reported in the literature in at least one individual affected with Beta Thalassemia (e.g. Eng_1993). To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication was ascertained in the context of this evaluation (PMID: 8257991). ClinVar contains an entry for this variant (Variation ID: 36303). Based on the evidence outlined above, the variant was classified as pathogenic. -

Nov 16, 2015

Counsyl

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

alpha Thalassemia;C0002895: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

Nov 24, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs34282684; hg19: chr11-5247917;