rs33933481

Variant names:

• chr16-173550-G-A
• rs33933481
• NM_000517.6:c.379G>A

Your query was ambiguous. Multiple possible variants found:

• chr16-173550-G-A
• chr16-173550-G-T
• chr16-173550-G-C

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP3_Strong PP5

The NM_000517.6(HBA2):​c.379G>A​(p.Asp127Asn) variant causes a missense change. The variant allele was found at a frequency of 0.00000137 in 1,459,020 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. D127G) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 25)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: HBA2 NM_000517.6 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:5 U:1 O:1
• Conservation: PhyloP100: 7.04
• Publications: 3 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: Pathogenic. The variant received 11 ACMG points.

• PM1: In a hotspot region, there are 7 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 10 uncertain in NM_000517.6
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr16-173550-G-T is described in ClinVar as Pathogenic. ClinVar VariationId is 439117.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.991
• PP5: Variant 16-173550-G-A is Pathogenic according to our data. Variant chr16-173550-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 15662.

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.379G>A	p.Asp127Asn	missense	Exon 3 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.379G>A	p.Asp127Asn	missense	Exon 3 of 3	ENSP00000251595.6	P69905
	HBA2	ENST00000482565.1	TSL:1	n.515G>A		non_coding_transcript_exon	Exon 2 of 2
	HBA2	ENST00000397806.1	TSL:2	c.283G>A	p.Asp95Asn	missense	Exon 3 of 3	ENSP00000380908.1	G3V1N2

Frequencies

GnomAD3 genomes Cov.: 25

GnomAD2 exomes AF: 0.00000402 AC: 1 AN: 248750 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000290

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1459020 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 725574

African (AFR) AF: 0.00 AC: 0 AN: 32132

American (AMR) AF: 0.0000224 AC: 1 AN: 44684

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26096

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39688

South Asian (SAS) AF: 0.00 AC: 0 AN: 85170

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53384

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5718

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111888

Other (OTH) AF: 0.00 AC: 0 AN: 60260

GnomAD4 genome Cov.: 25

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000113

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
4	-	-	not provided (4)
1	-	-	alpha Thalassemia;C0700299:Heinz body anemia;C3161174:Hemoglobin H disease;C4693823:Erythrocytosis, familial, 7 (1)
-	1	-	not specified (1)
-	-	-	HEMOGLOBIN TARRANT (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.91
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.080
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Benign	0.14	T
Eigen	Uncertain	0.63
Eigen_PC	Uncertain	0.57
FATHMM_MKL	Uncertain	0.94	D
M_CAP	Pathogenic	0.62	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	0.88	D
PhyloP100		7.0
PrimateAI	Uncertain	0.61	T
PROVEAN	Pathogenic	-4.7	D
REVEL	Pathogenic	0.88
Sift	Uncertain	0.025	D
Sift4G	Uncertain	0.023	D
Vest4		0.82
MutPred		0.95		Gain of MoRF binding (P = 0.0612)
MVP		1.0
MPC		2.2
ClinPred		1.0	D
GERP RS		4.2
gMVP		0.84
Mutation Taster		=19/81	disease causing (ClinVar)

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: rs33933481; hg19: chr16-223549; COSMIC: COSV107243508; COSMIC: COSV107243508;