rs34220980

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 20 ACMG points: 20P and 0B. PVS1PS1_ModeratePM2PP5_Very_Strong

The NM_000558.5(HBA1):c.1A>G(p.Met1?) variant causes a start lost change. The variant allele was found at a frequency of 0.0000263 in 152,232 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★).

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 29)

Exomes 𝑓: 0.0000096 ( 0 hom. )

Failed GnomAD Quality Control

Consequence

HBA1
NM_000558.5 start_lost

Scores

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:2

Conservation

PhyloP100: 5.12

Publications

15 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: Pathogenic. The variant received 20 ACMG points.

PVS1

Start lost variant, next in-frame start position is after 15 pathogenic variants. Next in-frame start position is after 33 codons. Genomic position: 176930. Lost 0.226 part of the original CDS.

PS1

Another start lost variant in NM_000558.5 (HBA1) was described as [Likely_pathogenic] in ClinVar

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 16-176717-A-G is Pathogenic according to our data. Variant chr16-176717-A-G is described in ClinVar as Pathogenic. ClinVar VariationId is 2428673.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HBA1	NM_000558.5 link	c.1A>G	p.Met1?	start_lost	Exon 1 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.1A>G	p.Met1?	start_lost	Exon 1 of 3	1	NM_000558.5	ENSP00000322421.5		P69905

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

152232

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000724

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000172

AC:

AN:

232006

AF XY:

0.0000237

show subpopulations

Gnomad AFR exome

AF:

0.000225

Gnomad AMR exome

AF:

0.00

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

Data not reliable, filtered out with message: AS_VQSR

AF:

0.00000963

AC:

AN:

1454214

Hom.:

Cov.:

AF XY:

0.00000968

AC XY:

AN XY:

722990

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.000121

AC:

AN:

33106

American (AMR)

AF:

0.00

AC:

AN:

43690

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25992

East Asian (EAS)

AF:

0.00

AC:

AN:

39356

South Asian (SAS)

AF:

0.0000704

AC:

AN:

85252

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52532

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5368

European-Non Finnish (NFE)

AF:

0.00000361

AC:

AN:

1108852

Other (OTH)

AF:

0.00

AC:

AN:

60066

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.304

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

AF:

0.0000263

AC:

AN:

152232

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74374

show subpopulations

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.0000724

AC:

AN:

41436

American (AMR)

AF:

0.00

AC:

AN:

15294

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5208

South Asian (SAS)

AF:

0.000207

AC:

AN:

4838

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10624

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68040

Other (OTH)

AF:

0.00

AC:

AN:

2092

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0.000356006), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.338

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.:

ExAC

AF:

0.0000166

AC:

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

alpha Thalassemia;C0700299:Heinz body anemia;C3161174:Hemoglobin H disease;C4693798:Methemoglobinemia, alpha type;C4693823:Erythrocytosis, familial, 7

Pathogenic:1

Feb 13, 2024

Fulgent Genetics, Fulgent Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not provided

Pathogenic:1

Apr 21, 2022

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The HBA1 c.1A>G; p.Met1? variant (rs34220980, HbVar ID: 1063), also known as alpha1 NcoI, is reported heterozygous in the literature in individuals with hypochromia and variable microcytosis (see Hbvar and references therein, Desogus 2015). Further, this variant has been observed in trans with double and single alpha globin gene deletions in individuals with Hb H disease and alpha thalassemia trait respectively (HbVar, Desogus 2015). This variant disrupts the translation initiation codon, resulting in reduced alpha globin protein. This variant is found in the African population with an allele frequency of 0.2% (4/22010 alleles) in the Genome Aggregation Database. Based on available information, this variant is considered to be pathogenic. References: Link to HbVar database: https://globin.bx.psu.edu/hbvar/menu.html Desogus MF et al. Investigating the alpha1(NcoI) mutation. Acta Haematol. 2015;133(2):145-7. PMID: 25247841. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.26

BayesDel_noAF

Pathogenic

0.42

CADD

Benign

(source)

DANN

Uncertain

0.99

DEOGEN2

Uncertain

0.55

Eigen

Uncertain

0.22

Eigen_PC

Uncertain

0.23

FATHMM_MKL

Uncertain

0.95

LIST_S2

Uncertain

0.90

M_CAP

Pathogenic

0.93

MetaRNN

Pathogenic

0.99

MetaSVM

Pathogenic

0.81

PhyloP100

5.1

PROVEAN

Uncertain

-2.4

REVEL

Pathogenic

0.88

Sift

Pathogenic

0.0

Sift4G

Pathogenic

0.0

Vest4

0.98

MutPred

1.0

Loss of MoRF binding (P = 0.0883);

MVP

1.0

ClinPred

0.93

GERP RS

4.5

PromoterAI

-0.26

Neutral

(source)

Varity_R

0.93

gMVP

0.69

Mutation Taster

=7/193

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.020

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