rs35654345

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 4P and 3B. PM1PM2BP4_ModerateBP6

The NM_000558.5(HBA1):c.341T>A(p.Leu114His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,460,452 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000034 ( 0 hom. )

Failed GnomAD Quality Control

Consequence

HBA1
NM_000558.5 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2B:1O:1

Conservation

PhyloP100: -0.253

Publications

3 publications found

Variant links:

Genes affected

HBA1 (HGNC:4823): (hemoglobin subunit alpha 1) The human alpha globin gene cluster located on chromosome 16 spans about 30 kb and includes seven loci: 5'- zeta - pseudozeta - mu - pseudoalpha-1 - alpha-2 - alpha-1 - theta - 3'. The alpha-2 (HBA2) and alpha-1 (HBA1) coding sequences are identical. These genes differ slightly over the 5' untranslated regions and the introns, but they differ significantly over the 3' untranslated regions. Two alpha chains plus two beta chains constitute HbA, which in normal adult life comprises about 97% of the total hemoglobin; alpha chains combine with delta chains to constitute HbA-2, which with HbF (fetal hemoglobin) makes up the remaining 3% of adult hemoglobin. Alpha thalassemias result from deletions of each of the alpha genes as well as deletions of both HBA2 and HBA1; some nondeletion alpha thalassemias have also been reported. [provided by RefSeq, Jul 2008]

HBA1 Gene-Disease associations (from GenCC):

alpha thalassemia spectrum
Inheritance: AR, SD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics
erythrocytosis, familial, 7
Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
hemoglobin M disease
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Hb Bart's hydrops fetalis
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
hemoglobin H disease
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
methemoglobinemia, alpha type
Inheritance: AD Classification: LIMITED Submitted by: ClinGen
Heinz body anemia
Inheritance: AR Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)

HBA1 links:

ENSG00000294436 (HGNC:):

ENSG00000294436 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

PM1

In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 4 benign, 14 uncertain in NM_000558.5

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.16644317).

BP6

Variant 16-177323-T-A is Benign according to our data. Variant chr16-177323-T-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 15829.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HBA1	NM_000558.5 link	c.341T>A	p.Leu114His	missense_variant	Exon 3 of 3	ENST00000320868.9	NP_000549.1	P69905D1MGQ2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HBA1	ENST00000320868.9 link	c.341T>A	p.Leu114His	missense_variant	Exon 3 of 3	1	NM_000558.5	ENSP00000322421.5		P69905

Frequencies

GnomAD3 genomes

AF:

0.00000658

AC:

AN:

152004

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000655

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000203

AC:

AN:

246076

AF XY:

0.0000224

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000146

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000342

AC:

AN:

1460452

Hom.:

Cov.:

AF XY:

0.00000413

AC XY:

AN XY:

726522

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33460

American (AMR)

AF:

0.000112

AC:

AN:

44598

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26072

East Asian (EAS)

AF:

0.00

AC:

AN:

39630

South Asian (SAS)

AF:

0.00

AC:

AN:

86144

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52862

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111604

Other (OTH)

AF:

0.00

AC:

AN:

60316

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Data not reliable, filtered out with message: AS_VQSR

AF:

0.00000658

AC:

AN:

152004

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74230

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41396

American (AMR)

AF:

0.0000655

AC:

AN:

15262

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5168

South Asian (SAS)

AF:

0.00

AC:

AN:

4814

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10602

Middle Eastern (MID)

AF:

0.00

AC:

AN:

314

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

67982

Other (OTH)

AF:

0.00

AC:

AN:

2084

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000756

ExAC

AF:

0.00000826

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2Benign:1Other:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:1Benign:1

Aug 28, 2024

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The Hb Twin Peaks variant (HBA1: c.341T>A; p.Leu114His, also known as Leu113His when numbered from the mature protein; rs35654345, HbVarID: 175) is reported in the literature as a stable hemoglobin variant and is not associated with clinical symptoms in a heterozygous state (HbVar database and references therein). In vitro studies also demonstrate that this variant increases the solubility of Hb S when forming the globin tetramer, potentially acting as an inhibitor of polymerization (Sivaram 2001). This variant is reported in ClinVar (Variation ID: 15829). This variant is found in the Latino population with an allele frequency of 0.0146% (5/34326 alleles), in the Genome Aggregation Database. Computational analyses are uncertain whether this variant is neutral or deleterious (REVEL: 0.376). Based on available information, the Hb Twin Peaks variant is considered to be likely benign. References: Link to HbVar database: https://globin.bx.psu.edu/hbvar/menu.html Sivaram M et al. A role for the alpha 113 (GH1) amino acid residue in the polymerization of sickle hemoglobin. Evaluation of its inhibitory strength and interaction linkage with two fiber contact sites (alpha 16/23) located in the AB region of the alpha-chain. J Biol Chem. 2001; 276(21):18209-15. PMID: 11259442. -

Jan 23, 2024

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The HBA1 c.341T>A (p.Leu114His) variant (also known as Hb Twin Peaks) has been reported to have normal stability, and individuals who are heterozygous for this variant have a normal clinical presentation (HbVar (http://globin.cse.psu.edu/cgi-bin/hbvar/counter) and PMID: 3839772 (1985)). This variant has been found to have anti-sickling effect when in association with HbS (PMID: 11259442 (2001)). Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is benign. Based on the available information, we are unable to determine the clinical significance of this variant. -

HBA1-related disorder

Uncertain:1

May 14, 2024

PreventionGenetics, part of Exact Sciences

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

The HBA1 c.341T>A variant is predicted to result in the amino acid substitution p.Leu114His. To our knowledge, this variant has not been reported in the literature in association with disease. This variant is reported in 0.015% of alleles in individuals of Latino descent in gnomAD. At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

HEMOGLOBIN TWIN PEAKS

Other:1

Jul 20, 2016

OMIM

Significance:other

Review Status:no assertion criteria provided

Collection Method:literature only

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.066

BayesDel_addAF

Benign

-0.083

BayesDel_noAF

Benign

-0.10

CADD

Benign

0.12

(source)

DANN

Benign

0.63

DEOGEN2

Benign

0.23

T;.

Eigen

Benign

-1.3

Eigen_PC

Benign

-1.5

FATHMM_MKL

Benign

0.035

LIST_S2

Benign

0.46

T;T

M_CAP

Uncertain

0.18

MetaRNN

Benign

0.17

T;T

MetaSVM

Benign

-0.31

PhyloP100

-0.25

PrimateAI

Benign

0.34

PROVEAN

Benign

2.1

N;N

REVEL

Uncertain

0.38

Sift

Benign

0.089

T;T

Sift4G

Benign

0.32

T;T

Vest4

0.18

MutPred

0.69

Gain of disorder (P = 0.0205);.;

MVP

0.87

ClinPred

0.063

GERP RS

-8.7

Varity_R

0.23

gMVP

0.93

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over