chr16-176762-G-T

Position:

chr16-176762-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The ENST00000320868.9(HBA1):c.46G>T(p.Gly16Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G16D) has been classified as Likely benign.

Frequency

Genomes: not found (cov: 28)

Exomes 𝑓: 7.0e-7 ( 0 hom. )

Failed GnomAD Quality Control

Consequence

HBA1
ENST00000320868.9 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: -0.533

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 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HBA1	NM_000558.5 linkuse as main transcript	c.46G>T	p.Gly16Cys	missense_variant	1/3	ENST00000320868.9	NP_000549.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris
HBA1	ENST00000320868.9 linkuse as main transcript	c.46G>T	p.Gly16Cys	missense_variant	1/3	1	NM_000558.5	ENSP00000322421	P1
HBA1	ENST00000472694.1 linkuse as main transcript	n.65G>T		non_coding_transcript_exon_variant	1/2	1
HBA1	ENST00000487791.1 linkuse as main transcript	n.15G>T		non_coding_transcript_exon_variant	1/2	1
HBA1	ENST00000397797.1 linkuse as main transcript	c.-2G>T		splice_region_variant, 5_prime_UTR_variant	1/3	2		ENSP00000380899

Frequencies

GnomAD3 genomes

Cov.:

GnomAD3 exomes

AF:

0.00000601

AC:

AN:

166306

Hom.:

AF XY:

0.00

AC XY:

AN XY:

89294

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 SAS exome

AF:

0.0000423

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:

6.96e-7

AC:

AN:

1437144

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

713566

show subpopulations

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:

0.0000120

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

Cov.:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

not specified

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Apr 18, 2024

Variant summary: HBA1 c.46G>T (p.Gly16Cys) results in a non-conservative amino acid change in the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 6e-06 in 166306 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.46G>T in individuals affected with Alpha Thalassemia and no experimental evidence demonstrating its impact on protein function have been reported. No submitters have cited clinical-significance assessments for this variant to ClinVar. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.27

BayesDel_addAF

Uncertain

0.14

BayesDel_noAF

Uncertain

-0.040

CADD

Benign

DANN

Uncertain

0.99

DEOGEN2

Benign

0.39

Eigen

Benign

-0.84

Eigen_PC

Benign

-1.0

FATHMM_MKL

Benign

0.48

LIST_S2

Benign

0.76

M_CAP

Pathogenic

0.59

MetaRNN

Uncertain

0.59

MetaSVM

Uncertain

0.31

MutationTaster

Benign

1.0

D;N

PrimateAI

Uncertain

0.49

PROVEAN

Uncertain

-3.2

REVEL

Uncertain

0.54

Sift

Uncertain

0.0010

Sift4G

Uncertain

0.0080

Vest4

0.36

MutPred

0.63

Gain of methylation at K17 (P = 0.0154);

MVP

0.95

ClinPred

0.24

GERP RS

-3.0

Varity_R

0.65

gMVP

0.77

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.030

Details are displayed if max score is > 0.2

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over