16-172958-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM5 PP3

The NM_000517.6(HBA2):c.46G>C(p.Gly16Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another nucleotide change resulting in same amino acid change has been previously reported as Likely benignin UniProt. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G16C) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 2)
• Consequence: HBA2 NM_000517.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.396

Genes affected

HBA2 (HGNC:4824): (hemoglobin subunit alpha 2) 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]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM5: Other missense variant is known to change same aminoacid residue: Variant chr16-172958-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1683493.Status of the report is no_assertion_criteria_provided, 0 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.806

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HBA2	NM_000517.6	c.46G>C	p.Gly16Arg	missense_variant	1/3	ENST00000251595.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HBA2	ENST00000251595.11	c.46G>C	p.Gly16Arg	missense_variant	1/3	1	NM_000517.6	P1
HBA2	ENST00000484216.1	c.16G>C	p.Gly6Arg	missense_variant	1/2	1
HBA2	ENST00000482565.1	n.65G>C		non_coding_transcript_exon_variant	1/2	1
HBA2	ENST00000397806.1	c.-2G>C		splice_region_variant, 5_prime_UTR_variant	1/3	2

Frequencies

GnomAD3 genomes Cov.: 2

GnomAD4 exome Cov.: 0

GnomAD4 genome Cov.: 2

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Quest Diagnostics Nichols Institute San Juan Capistrano

Jul 23, 2021

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Uncertain	0.11
Cadd	Benign	18
Dann	Benign	0.93
Eigen	Benign	-0.85
Eigen_PC	Benign	-0.98
FATHMM_MKL	Benign	0.51	D
M_CAP	Pathogenic	0.75	D
MetaRNN	Pathogenic	0.81	D
MetaSVM	Uncertain	0.23	D
MutationTaster	Benign	1.0	D;N
PrimateAI	Uncertain	0.70	T
PROVEAN	Benign	-1.6	N
REVEL	Uncertain	0.62
Sift	Uncertain	0.021	D
Sift4G	Benign	0.10	T
Vest4		0.56
MutPred		0.47		Gain of MoRF binding (P = 0.0113);
MVP		0.96
MPC		1.5
ClinPred		0.16	T
GERP RS		-0.90
gMVP		0.79

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

Other links and lift over

dbSNP: rs281864811; hg19: chr16-222957;