16-172950-C-T

Variant names:

• chr16-172950-C-T
• rs281864809
• NM_000517.6:c.38C>T

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM1

The NM_000517.6(HBA2):​c.38C>T​(p.Ala13Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. 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. A13D) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 1)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: HBA2 NM_000517.6 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.164
• Publications: 1 publications found

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]

HBA2 Gene-Disease associations (from GenCC):

• alpha thalassemia spectrum

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), ClinGen
• erythrocytosis, familial, 7

  Inheritance: AD Classification: STRONG, LIMITED Submitted by: Genomics England PanelApp, ClinGen, Labcorp Genetics (formerly Invitae)
• 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
• Heinz body anemia

  Inheritance: AD Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)
• methemoglobinemia, alpha type

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen
• unstable hemoglobin disease

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen

ENSG00000294455 (HGNC:):

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 6 benign, 8 uncertain in NM_000517.6

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000517.6. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HBA2	NM_000517.6	MANE Select	c.38C>T	p.Ala13Val	missense	Exon 1 of 3	NP_000508.1	D1MGQ2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HBA2	ENST00000251595.11	TSL:1 MANE Select	c.38C>T	p.Ala13Val	missense	Exon 1 of 3	ENSP00000251595.6	P69905
	HBA2	ENST00000484216.1	TSL:1	c.5C>T	p.Ala2Val	missense	Exon 1 of 2	ENSP00000495899.1	A0A2R8Y7C0
	HBA2	ENST00000482565.1	TSL:1	n.57C>T		non_coding_transcript_exon	Exon 1 of 2

Frequencies

GnomAD3 genomes Cov.: 1

GnomAD2 exomes AF: 0.0000563 AC: 3 AN: 53250 AF XY: 0.0000745

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: 0.000149

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000815 AC: 3 AN: 368084 Hom.: 0 Cov.: 0 AF XY: 0.0000103 AC XY: 2 AN XY: 193584

African (AFR) AF: 0.00 AC: 0 AN: 8872

American (AMR) AF: 0.00 AC: 0 AN: 16142

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 11266

East Asian (EAS) AF: 0.00 AC: 0 AN: 24174

South Asian (SAS) AF: 0.00 AC: 0 AN: 43562

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 22938

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 1562

European-Non Finnish (NFE) AF: 0.0000137 AC: 3 AN: 218702

Other (OTH) AF: 0.00 AC: 0 AN: 20866

GnomAD4 genome Cov.: 1

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Benign	-0.029	T
BayesDel_noAF	Uncertain	-0.020
CADD	Benign	18
DANN	Uncertain	0.99
Eigen	Benign	-0.76
Eigen_PC	Benign	-0.86
FATHMM_MKL	Benign	0.12	N
M_CAP	Pathogenic	0.48	D
MetaRNN	Uncertain	0.53	D
MetaSVM	Uncertain	0.065	D
PhyloP100		0.16
PrimateAI	Uncertain	0.73	T
PROVEAN	Uncertain	-2.4	N
REVEL	Uncertain	0.51
Sift	Uncertain	0.0010	D
Sift4G	Benign	0.061	T
Vest4		0.34
MutPred		0.68		Gain of methylation at K12 (P = 0.0365)
MVP		1.0
MPC		1.3
ClinPred		0.15	T
GERP RS		1.5
PromoterAI		-0.067	Neutral
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0
gMVP		0.68

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

Other links and lift over

dbSNP: rs281864809; hg19: chr16-222949;