16-172917-T-C

Position:

• chr16-172917-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PP3_Strong

The NM_000517.6(HBA2):​c.5T>C​(p.Val2Ala) variant causes a missense change involving the alteration of a non-conserved nucleotide. In-silico tool predicts a pathogenic outcome for this variant. 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. V2E) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 0)
• Consequence: HBA2 NM_000517.6 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.940

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 4 ACMG points.

• PP3: MetaRNN computational evidence supports a deleterious effect, 0.943

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HBA2	NM_000517.6	c.5T>C	p.Val2Ala	missense_variant	1/3	ENST00000251595.11	NP_000508.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
HBA2	ENST00000251595.11	c.5T>C	p.Val2Ala	missense_variant	1/3	1	NM_000517.6	ENSP00000251595	P1
HBA2	ENST00000482565.1	n.24T>C		non_coding_transcript_exon_variant	1/2	1
HBA2	ENST00000397806.1	c.-43T>C		5_prime_UTR_variant	1/3	2		ENSP00000380908
HBA2	ENST00000484216.1			upstream_gene_variant		1		ENSP00000495899

Frequencies

GnomAD3 genomes Cov.: 0

GnomAD4 exome Cov.: 0

GnomAD4 genome Cov.: 0

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.34	D
BayesDel_noAF	Pathogenic	0.25
CADD	Benign	21
DANN	Benign	0.91
Eigen	Benign	-0.27
Eigen_PC	Benign	-0.18
FATHMM_MKL	Uncertain	0.84	D
M_CAP	Pathogenic	0.70	D
MetaRNN	Pathogenic	0.94	D
MetaSVM	Uncertain	0.080	D
MutationTaster	Benign	0.90	D;D
PrimateAI	Pathogenic	0.86	D
PROVEAN	Benign	-1.3	N
REVEL	Uncertain	0.61
Sift	Uncertain	0.0010	D
Sift4G	Benign	0.29	T
Vest4		0.62
MutPred		0.84		Gain of glycosylation at S4 (P = 0.0991);
MVP		0.99
MPC		1.7
ClinPred		0.38	T
GERP RS		3.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.6
gMVP		0.60

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs33981821; hg19: chr16-222916;