rs63750628

Positions:

• chr11-5227052-G-A
• chr11-5227052-G-T

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 2P and 5B. PM2 BP4_Strong BP6

The NM_000518.5(HBB):​c.-31C>T variant causes a 5 prime UTR premature start codon gain change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000337 in 1,424,176 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.000033 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000034 (0 hom.)
• Consequence: HBB NM_000518.5 5_prime_UTR_premature_start_codon_gain
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:5 B:7
• Conservation: PhyloP100: -0.619

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 Likely_benign. Variant got -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.54).
• BP6: Variant 11-5227052-G-A is Benign according to our data. Variant chr11-5227052-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 36291.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=4, Uncertain_significance=3, Benign=2}. Variant chr11-5227052-G-A is described in Lovd as [Benign].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HBB	NM_000518.5	c.-31C>T		5_prime_UTR_premature_start_codon_gain_variant	1/3	ENST00000335295.4	NP_000509.1
HBB	NM_000518.5	c.-31C>T		5_prime_UTR_variant	1/3	ENST00000335295.4	NP_000509.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
HBB	ENST00000335295.4	c.-31C>T		5_prime_UTR_premature_start_codon_gain_variant	1/3	1	NM_000518.5	ENSP00000333994.3
HBB	ENST00000335295.4	c.-31C>T		5_prime_UTR_variant	1/3	1	NM_000518.5	ENSP00000333994.3

Frequencies

GnomAD3 genomes AF: 0.0000328 AC: 5 AN: 152208 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000735

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000638 AC: 16 AN: 250664 Hom.: 0 AF XY: 0.0000886 AC XY: 12 AN XY: 135456

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000141

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000338 AC: 43 AN: 1271968 Hom.: 0 Cov.: 19 AF XY: 0.0000296 AC XY: 19 AN XY: 642800

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000416

Gnomad4 OTH exome AF: 0.0000552

GnomAD4 genome AF: 0.0000328 AC: 5 AN: 152208 Hom.: 0 Cov.: 33 AF XY: 0.0000134 AC XY: 1 AN XY: 74350

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000735

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000673 Hom.: 0

Bravo AF: 0.0000264

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:5 Benign:7

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Benign:3

Likely benign, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Nov 15, 2023	- -
Likely benign, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Jan 18, 2022	- -
Likely benign, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Aug 01, 2024	HBB: PP4, BP2, BP5 -

beta Thalassemia Uncertain:1 Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Dec 05, 2018	The HBB c.-31C>T variant, commonly referred to as 5’UTR+20, C>T, has been described in at least four studies in which it is found in cis with the same intronic variant, c.316-106C>G (commonly referred to as IVS-II-745 (C>G)). The c.-31C>T variant was found in a homozygous state in three individuals with a severe form of beta-thalassemia, in a compound heterozygous state in an additional three individuals with the same severe phenotype, and in a heterozygous state in six individuals, all with a milder phenotype. In all cases, the c.-31C>T variant was in cis with the intronic variant (Yavarian et al. 2001; Liaw et al. 2009; Ropero et al. 2013; Farashi et al. 2015). Sirdah et al. (2013) also reported the c.-31C>T variant in a compound heterozygous state in one individual with beta-thalassemia who did not carry the intronic variant. The c.-31C>T variant is reported at a frequency of 0.00014 in the European (non-Finnish) population of the Exome Aggregation Consortium. Based on the evidence, the c.-31C>T variant is classified as a variant of unknown significance for HBB-related disorders. -
Benign, no assertion criteria provided	curation	The ITHANET community portal, The Cyprus Institute of Neurology and Genetics	Nov 25, 2019	- -

Dominant beta-thalassemia Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Genetics and Molecular Pathology, SA Pathology

Feb 21, 2020

- -

HBB-related disorder Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

May 28, 2024

The HBB c.-31C>T variant is located in the 5' untranslated region. This variant has also been described in the literature as 5' UTR+20(C>T) or +20(C>T) or 5’UTR-31(C>T) or C>T at nt +20 to the Cap site or β++20 (C>T). This variant has been frequently observed on the same allele (in cis) with the disease-causing variant c.316-106C>G (a.k.a. "IVS-II-745") in multiple individuals with beta thalassemia (Table 1, footnotes, Reported as C>T at nt position +20 to the Cap site, Gonzalez-Redondo et al. 1989. PubMed ID: 2713503; Reported as β++20 (C>T), Lemsaddek et al. 2003. PubMed ID: 12827652; Table 1, n 22, Reported as IVS-II-745 (C>G)+5’UTR+20(C>T), Galehdari et al. 2010. PubMed ID: 20854120; Table 1, Reported as +20(C>T), Ropero et al. 2013. PubMed ID: 23425204; Table 1 and 2, Reported as c.-31C>T, Carrocini et al. 2017. PubMed ID: 28366028). However, it has also been observed without the c.316-106C>G variant in a severely affected individual who was potentially compound heterozygous for c.-31C>T and a second pathogenic HBB variant, c.93-21G>A [a.k.a. "IVS-1-110 (G>A)"] (Tables 3 and 4, Reported as 5’UTR;+20(C>T), c.-31C>T, and 5’UTR-31(C>T), Sirdah et al. 2013. PubMed ID: 23321370). Additionally, an in vitro RT-PCR-based study reported a ~50% reduction in HBB mRNA expression for the c.-31C>T allele (without c.316-106C>G) relative to wild type (Table 1, Reported as +20C>T, Irenge et al. 2002. PubMed ID: 12324499). This variant is reported in 0.014% of alleles in individuals of European (Non-Finnish) descent in gnomAD. At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Fetal hemoglobin quantitative trait locus 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Apr 27, 2017

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

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 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

May 07, 2024

- -

not specified Benign:1

Likely benign, criteria provided, single submitter

clinical testing

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

Nov 08, 2023

Variant summary: HBB c.-31C>T is located in the untranslated mRNA region upstream of the initiation codon. The variant allele was found at a frequency of 6.4e-05 in 250664 control chromosomes (gnomAD). This frequency is not significantly higher than expected for a pathogenic variant in HBB causing Beta Thalassemia (6.4e-05 vs 0.011), allowing no conclusion about variant significance. c.-31C>T has been widely reported in the literature to co-occur in cis with other disease causing variants such as IVS-II-745C>G (c.316-106C>G) in individuals affected with Beta Thalassemia (example, Gonzalez-Redondo_1989, Lemsaddek_2003, Yavarian_2001, Galehdari_2011). These report(s) do not provide unequivocal conclusions about association of the variant with Beta Thalassemia. Locus specific databases report this variant predominantly as benign. At least one publication reports experimental evidence evaluating an impact on expression of beta globin mRNA, however, does not allow convincing conclusions about the variant effect (example, Irenge_2002). The following publications have been ascertained in the context of this evaluation (PMID: 18976160, 20854120, 22737496, 2713503, 20113284, 12324499, 12827652, 19657842, 20704537, 15108284, 11300348). Six clinical diagnostic laboratories and a database (ITHANET) have submitted clinical-significance assessments for this variant to ClinVar after 2014 without and classifed the variant as benign/likely benign (n=4) and VUS (n=1). Based on the evidence outlined above, the variant was classified as likely benign. -

Hemoglobin E Benign:1

Benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Apr 27, 2017

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -

Hb SS disease Benign:1

Benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Apr 27, 2017

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.54
CADD	Benign	9.5
DANN	Benign	0.92

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: rs63750628; hg19: chr11-5248282;