rs34218908

Variant names:

• chr11-5226665-AG-A
• rs34218908
• NM_000518.5:c.226delC

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.226delC​(p.Leu76TrpfsTer14) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: HBB NM_000518.5 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 0.0470

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 78 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-5226665-AG-A is Pathogenic according to our data. Variant chr11-5226665-AG-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 495983.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-5226665-AG-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HBB	NM_000518.5	c.226delC	p.Leu76TrpfsTer14	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.226delC	p.Leu76TrpfsTer14	frameshift_variant	Exon 2 of 3	1	NM_000518.5	ENSP00000333994.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 36

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

beta Thalassemia Pathogenic:1

Feb 08, 2016

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

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: Variant is a deletion of a nucleotide resulting in a frameshift mutation and mutation taster predicts this variant to be disease causing. Frameshift mutations in HBB are known mechanism of the disease (GeneReviews). It is absent from the large and broad cohorts of the ExAC project while it was observed in a patient with transfusion dependent sever thalassemia in homozygosity indicating a pathogenic impact (Basak_1992). It was also observed in a patient with 0 phenotype in compound heterozygosity with a codon 5 mutation (Sarookhani_2010). Considering all evidence, the variant was classified as Likely Pathogenic. -

not provided Pathogenic:1

Feb 25, 2024

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.Leu76Trpfs*14) 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: 1517110). This variant is also known as deletion of C in codon 74. ClinVar contains an entry for this variant (Variation ID: 495983). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs34218908; hg19: chr11-5247895;