16-173125-G-A

Variant names:

• chr16-173125-G-A
• rs111033606
• NM_000517.6:c.96G>A

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 0P and 5B. BP4_Strong BP7

The NM_000517.6(HBA2):​c.96G>A​(p.Arg32Arg) variant causes a splice region, synonymous change involving the alteration of a non-conserved nucleotide. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. R32R) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 9)
• Consequence: HBA2 NM_000517.6 splice_region, synonymous
• Scores: Splicing: ADA: 0.0003939
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.90
• Publications: 2 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: Likely_benign. The variant received -5 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.48).
• BP7: Synonymous conserved (PhyloP=1.9 with no splicing effect.

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.96G>A	p.Arg32Arg	splice_region synonymous	Exon 2 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.96G>A	p.Arg32Arg	splice_region synonymous	Exon 2 of 3	ENSP00000251595.6	P69905
	HBA2	ENST00000484216.1	TSL:1	c.63G>A	p.Arg21Arg	splice_region synonymous	Exon 2 of 2	ENSP00000495899.1	A0A2R8Y7C0
	HBA2	ENST00000482565.1	TSL:1	n.232G>A		non_coding_transcript_exon	Exon 1 of 2

Frequencies

GnomAD3 genomes Cov.: 9

GnomAD4 exome Cov.: 7

GnomAD4 genome Cov.: 9

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.48
CADD	Benign	17
DANN	Benign	0.81
PhyloP100		1.9
PromoterAI		-0.043	Neutral
Mutation Taster		=50/50

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.00039
dbscSNV1_RF	Benign	0.15
SpliceAI score (max)		0.020		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: rs111033606; hg19: chr16-223124;