Genetic Variant NM_000558.5:c.392C>T (chr16-177374-C-T) – ACMG Classification: Uncertain_significance (4 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM1PM2

The NM_000558.5(HBA1):c.392C>T(p.Ala131Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,460 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A131D) has been classified as Uncertain significance.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

HBA1
NM_000558.5 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: -0.724

Publications

4 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:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

PM1

In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 13 uncertain in NM_000558.5

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HBA1	NM_000558.5 link	c.392C>T	p.Ala131Val	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.392C>T	p.Ala131Val	missense_variant	Exon 3 of 3	1	NM_000558.5	ENSP00000322421.5		P69905

Frequencies

GnomAD3 genomes

Cov.:

GnomAD2 exomes

AF:

0.00000802

AC:

AN:

249270

AF XY:

0.00000740

show subpopulations

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 FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000178

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461460

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727042

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33478

American (AMR)

AF:

0.00

AC:

AN:

44690

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26126

East Asian (EAS)

AF:

0.00

AC:

AN:

39690

South Asian (SAS)

AF:

0.00

AC:

AN:

86210

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53180

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

8.99e-7

AC:

AN:

1111940

Other (OTH)

AF:

0.00

AC:

AN:

60378

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

Cov.:

ExAC

AF:

0.00000825

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.0000593

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.28

BayesDel_addAF

Uncertain

0.13

BayesDel_noAF

Uncertain

-0.040

CADD

Benign

(source)

DANN

Uncertain

0.99

DEOGEN2

Uncertain

0.60

D;.

Eigen

Benign

-0.62

Eigen_PC

Benign

-0.81

FATHMM_MKL

Benign

0.26

LIST_S2

Uncertain

0.88

D;D

M_CAP

Pathogenic

0.56

MetaRNN

Uncertain

0.60

D;D

MetaSVM

Uncertain

0.29

PhyloP100

-0.72

PrimateAI

Benign

0.39

PROVEAN

Uncertain

-2.8

D;D

REVEL

Uncertain

0.55

Sift

Pathogenic

0.0

D;D

Sift4G

Benign

0.068

T;T

Vest4

0.32

MutPred

0.55

Loss of ubiquitination at K128 (P = 0.1055);.;

MVP

1.0

ClinPred

0.96

GERP RS

-2.8

Varity_R

0.30

gMVP

0.84

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

ClinVar

Computational scores

Splicing

Publications

Other links and lift over