rs35703285

chr11-5225740-A-C

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 10P and 1B. PM2 PP5_Very_Strong BP4

The NM_000518.5(HBB):c.316-14T>G variant causes a splice polypyrimidine tract, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000479 in 1,461,540 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 Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: HBB NM_000518.5 splice_polypyrimidine_tract, intron
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:9
• Conservation: PhyloP100: 0.354

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_pathogenic. Variant got 9 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-5225740-A-C is Pathogenic according to our data. Variant chr11-5225740-A-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 36313.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-5225740-A-C is described in Lovd as [Pathogenic].
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.81).. Strength limited to SUPPORTING due to the PP5.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HBB	NM_000518.5	c.316-14T>G		splice_polypyrimidine_tract_variant, intron_variant		ENST00000335295.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HBB	ENST00000335295.4	c.316-14T>G		splice_polypyrimidine_tract_variant, intron_variant		1	NM_000518.5	P1
HBB	ENST00000647020.1	c.316-14T>G		splice_polypyrimidine_tract_variant, intron_variant				P1
HBB	ENST00000633227.1	c.*132-14T>G		splice_polypyrimidine_tract_variant, intron_variant, NMD_transcript_variant		3
HBB	ENST00000475226.1	n.248-14T>G		splice_polypyrimidine_tract_variant, intron_variant, non_coding_transcript_variant		2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000479 AC: 7 AN: 1461540 Hom.: 0 Cov.: 31 AF XY: 0.00000550 AC XY: 4 AN XY: 727078

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: 0.0000580

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.00e-7

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:9

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:6

Pathogenic, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Mar 02, 2022	This variant has not been reported in large, multi-ethnic general populations (http://gnomad.broadinstitute.org). In the published literature, the variant is associated with beta(+)-thalassemia or beta(0)-thalassemia (PMID: 1772786 (1991), 18294253 (2008), 19205975 (2009), 22734501 (2012)). Analysis of this variant using software algorithms for the prediction of the effect of nucleotide changes on HBB mRNA splicing yielded predictions that this variant may result in the gain of a cryptic splice site without affecting the natural splice sites. Based on the available information, this variant is classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Mar 24, 2020	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Sep 02, 2023	Observed with a pathogenic variant in a patient with beta-thalassemia in published literature, but it is not known whether the variants occurred on the same (in cis) or on different (in trans) chromosomes (Luo et al., 2005; Gupta et al., 2023); Reported as a common variant among individuals of South Indian background (Sinha et al., 2009; Baysham et al., 2012); Not observed in large population cohorts (gnomAD); In silico analysis supports a deleterious effect on splicing; Also known as IVS-II-837 (T>G) using alternate nomenclature; This variant is associated with the following publications: (PMID: 30489691, 31766235, 1772786, 32412692, 23651435, 18294253, 22734501, 12709369, 15278762, 19254853, 23590658, 20437613, 19205975, 35620315, Gupta[article]2023, 33829933, 21119755, 15933066, 20230396) -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Oct 22, 2023	This sequence change falls in intron 2 of the HBB gene. It does not directly change the encoded amino acid sequence of the HBB protein. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with beta thalasemia (PMID: 15933066, 19205975, 22734501, 23590658). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. This variant is also known as IVS II:837 T>G. ClinVar contains an entry for this variant (Variation ID: 36313). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Feb 07, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Jul 13, 2023	The HBB c.316-14T>G variant (rs35703285, HbVar ID: 895), also known as IVS-II-837T>G, has been reported in the heterozygous state in individuals affected with microcytosis and hypochromia and is associated with an intermediate beta thalassemia phenotype when in combination with a beta(0) HBB variant on the opposite chromosome (Link to HbVar, Luo 2005, Nadkarni 2009, Sinha 2009, Varawalla 1991). It is reported in ClinVar (Variation ID: 36313) and absent from the Genome Aggregation Database, indicating it is not a common polymorphism. This is an intronic variant in a moderately conserved nucleotide, and computational analyses (Alamut v.2.11) predict that this variant may impact splicing by creating a novel cryptic acceptor splice site. Based on available information, this variant is considered pathogenic. References: Link to HbVar: https://globin.bx.psu.edu/hbvar/hbvar.html Luo H et al. Patients with thalassemia in the United States. Blood. 2005 Jun 15;105(12):4896-7. PMID: 15933066. Nadkarni A et al. Hematological and molecular analysis of novel and rare beta-thalassemia mutations in the Indian population. Hemoglobin. 2009;33(1):59-65. PMID: 19205975. Sinha S et al. Profiling B-thalassaemia mutations in India at state and regional levels: implications for genetic education, screening and counselling programmes. Hugo J. 2009 Dec;3(1-4):51-62. PMID: 21119755 Varawalla N et al. Rare beta-thalassaemia mutations in Asian indians. Br J Haematol. 1991 Dec;79(4):640-4. PMID: 1772786. -

beta Thalassemia Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing;curation	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 18, 2011	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Genetics and Molecular Pathology, SA Pathology	Jul 26, 2022	- -
Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.81
Cadd	Benign	3.9
Dann	Benign	0.80

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.89		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.49		Position offset: -1
DS_AL_spliceai		0.89		Position offset: -14

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

Publications

LitVar

Other links and lift over

dbSNP: rs35703285; hg19: chr11-5246970;