rs1554917561

chr11-5225663-CTGGTGGGG-C

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PVS1 PP5_Very_Strong

The NM_000518.5(HBB):c.371_378del(p.Thr124SerfsTer14) variant causes a frameshift change. Variant has been reported in ClinVar as Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. T124T) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: HBB NM_000518.5 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 5.97

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 16 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. There are 62 pathogenic variants in the truncated region.
• PP5: Variant 11-5225663-CTGGTGGGG-C is Pathogenic according to our data. Variant chr11-5225663-CTGGTGGGG-C is described in ClinVar as [Pathogenic]. Clinvar id is 495998.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-5225663-CTGGTGGGG-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HBB	NM_000518.5	c.371_378del	p.Thr124SerfsTer14	frameshift_variant	3/3	ENST00000335295.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HBB	ENST00000335295.4	c.371_378del	p.Thr124SerfsTer14	frameshift_variant	3/3	1	NM_000518.5	P1
HBB	ENST00000647020.1	c.371_378del	p.Thr124SerfsTer14	frameshift_variant	3/3			P1
HBB	ENST00000475226.1	n.303_310del		non_coding_transcript_exon_variant	2/2	2
HBB	ENST00000633227.1	c.*187_*194del		3_prime_UTR_variant, NMD_transcript_variant	3/3	3

Frequencies

GnomAD3 genomes Cov.: 33

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

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Jan 30, 2019

The HBB: c.371_378delCCCCACCA; p.Thr124fs variant (known as Thr123fs when numbered from the mature protein) (rs1554917561), also known as Codons 123/124/125 (-ACCCCACC), is reported in the literature in several individuals affected with beta-thalassemia (Boonyawat 2014, Fucharoen 1991, HbVar database). Both affected individuals had inclusion bodies observed (Boonyawat 2014, Fucharoen 1991), and one individual with severe disease also carried a mild Hb E variant (Fucharoen 1991). This variant is absent from general population databases (Exome Variant Server, Genome Aggregation Database), indicating it is not a common polymorphism. This variant results in a frameshift and premature termination codon in the last exon of the HBB gene, which may not lead to nonsense-mediated decay but is expected to create a truncated HBB protein. Hemoglobin analysis of an affected individual with this variant indicated an absence of truncated protein, suggesting this variant is highly unstable (Fucharoen 1991). Based on available information, this variant is considered to be pathogenic. References: HbVar link to Codons 123/124/125: http://globin.bx.psu.edu/cgi-bin/hbvar/query_vars3?mode=output&display_format=page&i=953 Boonyawat B et al. Molecular analysis of beta-globin gene mutations among Thai beta-thalassemia children: results from a single center study. Appl Clin Genet. 2014 Dec 10;7:253-8. Fucharoen G et al. Eight-base deletion in exon 3 of the beta-globin gene produced a novel variant (beta khon kaen) with an inclusion body beta-thalassemia trait. Blood. 1991 Jul 15;78(2):537-9. -

beta Thalassemia Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

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

Jan 05, 2017

Variant summary: The HBB c.371_378delCCCCACCA (p.Thr124Serfs) variant results in a premature termination codon. The variant is reported as a dominant BTHAL-causing mutation in literature and in databases (ITHA.net and HbVar). This variant has not been observed in general population. This frame-shift variant was first identified in one Thai B-THAL patient who was negative for other mutations upon screening for gross deletions in alfa gene cluster and all exons and exon-intron boundaries of the beta-globin gene (Fucharoean 1991). No abnormal protein was detected in the patient, suggesting that this beta-globin variant is highly unstable and likely to be degraded soon after translation. The variant was also reported in another patient from the same country who also had dominant beta-thalassemia (Boonyawat 2014).Taken together, the variant is classified to be pathogenic for dominant B-THAL. -

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: rs1554917561; hg19: chr11-5246893;