rs35578002

Positions:

• chr11-5226932-G-A
• chr11-5226932-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP5

The NM_000518.5(HBB):​c.90C>T​(p.Gly30Gly) variant causes a splice region, synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,460,284 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. G30G) has been classified as Benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: HBB NM_000518.5 splice_region, synonymous
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:6 U:1
• Conservation: PhyloP100: 3.56

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 Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-5226932-G-A is Pathogenic according to our data. Variant chr11-5226932-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 38682.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Pathogenic=1, Likely_pathogenic=2}. Variant chr11-5226932-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HBB	NM_000518.5	c.90C>T	p.Gly30Gly	splice_region_variant, synonymous_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.90C>T	p.Gly30Gly	splice_region_variant, synonymous_variant	1/3	1	NM_000518.5	ENSP00000333994.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251342 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135828

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: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1460284 Hom.: 0 Cov.: 33 AF XY: 0.00000551 AC XY: 4 AN XY: 726568

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: 0.0000348

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:6 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

beta Thalassemia Pathogenic:4

Pathogenic, no assertion criteria provided	clinical testing	Molecular Genetics Laboratory, BC Children's and BC Women's Hospitals	Oct 15, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Dec 07, 2016	Variant summary: The HBB c.90C>T (p.Gly30Gly) variant involves the alteration of a conserved nucleotide, resulting in a synonymous change. One in silico tool predicts a damaging outcome for this variant. 4/5 splice prediction tools predict that this varaint may create a novel 5' splicing donor site and a frameshift change. However, these predictions have yet to be confirmed by functional studies. This variant was found in 1/121334 control chromosomes at a frequency of 0.0000082, which does not exceed the estimated maximal expected allele frequency of a pathogenic HBB variant (0.0111803). However, this variant has been reported as a mild beta+ type mutation in numerous patients with beta thalassemia intermedia in homozygous and compound heterozygous states. Ithanet lists variant as a globin gene causative mutation. Taken together, this variant is classified as pathogenic. -
Pathogenic, no assertion criteria provided	curation	The ITHANET community portal, The Cyprus Institute of Neurology and Genetics	Nov 25, 2019	- -
Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Mar 17, 2017	- -

not provided Pathogenic:2 Uncertain:1

Likely pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	May 06, 2022	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Clinical Genetics and Genomics, Karolinska University Hospital	Jan 31, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Aug 29, 2023	The HBB c.90C>T (p.Gly30=) synonymous variant has been reported in the published literature in individuals affected with beta(+) thalassemia (PMID: 7786794 (1995), 3828533 (1987)). Additionally, this variant might affect splicing and this might cause the observed beta(+) phenotype in one study (PMID: 3828533 (1987)), and low expression levels of hemoglobin in another study (PMID: 7786794 (1995)). The frequency of this variant in the general population, 0.000004 (1/251342 chromosomes (Genome Aggregation Database, http://gnomad.broadinstitute.org)), is uninformative in the assessment of its pathogenicity. Analysis of this variant using software algorithms for the prediction of the effect of nucleotide changes on HBB mRNA splicing yielded inconclusive findings . Based on the available information, we are unable to determine the clinical significance of this variant. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.20
CADD	Uncertain	25
DANN	Benign	0.95

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.99
SpliceAI score (max)		0.82		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.82		Position offset: 2
DS_DL_spliceai		0.27		Position offset: -2

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

Publications

LitVar

Other links and lift over

dbSNP: rs35578002; hg19: chr11-5248162;