rs34533941

Positions:

• chr11-5226608-T-TCA

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000518.5(HBB):​c.283_284insTG​(p.Asp95ValfsTer65) 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 (★). Synonymous variant affecting the same amino acid position (i.e. D95D) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: HBB NM_000518.5 frameshift
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 1.30

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 12 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 139 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-5226608-T-TCA is Pathogenic according to our data. Variant chr11-5226608-T-TCA is described in ClinVar as [Likely_pathogenic]. Clinvar id is 15428.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HBB	NM_000518.5	c.283_284insTG	p.Asp95ValfsTer65	frameshift_variant	2/3	ENST00000335295.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HBB	ENST00000335295.4	c.283_284insTG	p.Asp95ValfsTer65	frameshift_variant	2/3	1	NM_000518.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 36

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Dominant beta-thalassemia Pathogenic:1

Likely pathogenic, criteria provided, single submitter

curation

Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard

Jan 25, 2023

The heterozygous p.Asp95ValfsTer65 variant in HBB was identified by our study in one individual with beta-thalassemia. The p.Asp95ValfsTer65 variant in HBB has been previously reported in one individual with beta-thalassemia (PMID: 2291578). This variant has also been reported in ClinVar (Variation ID: 15428) and has been interpreted by OMIM as pathogenic. This variant was absent from large population studies. This variant is predicted to cause a frameshift, which alters the protein’s amino acid sequence beginning at position 95 and leads to a premature termination codon 65 amino acids downstream. This termination codon occurs within the terminal 50 bases of the last exon and is more likely to escape nonsense mediated decay (NMD) and result in a truncated protein. Heterozygous loss of function of the HBB gene is an established disease mechanism in autosomal dominant beta-thalassemia. In summary, although additional studies are required to fully establish its clinical significance, this variant is likely pathogenic for autosomal dominant beta-thalassemia. ACMG/AMP Criteria applied: PVS1_Strong, PM2_Supporting, PS4_Supporting (Richards 2015). -

Beta zero thalassemia Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Jan 01, 1990

- -

Computational scores

Source: dbNSFP v4.3

Splicing

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

Publications

LitVar

Other links and lift over

dbSNP: rs34533941; hg19: chr11-5247838;