chr16-172952-G-C

Position:

• chr16-172952-G-C

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 0P and 1B. BP6

The NM_000517.6(HBA2):​c.40G>C​(p.Ala14Pro) variant causes a missense change involving the alteration of a non-conserved nucleotide. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another nucleotide change resulting in same amino acid change has been previously reported as Likely benignin UniProt.

• Frequency:
  • Genomes: not found (cov: 1)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: HBA2 NM_000517.6 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: -0.945

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 (HGNC:):

ACMG classification

Verdict is Likely_benign. Variant got -1 ACMG points.

• BP6: Variant 16-172952-G-C is Benign according to our data. Variant chr16-172952-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 801175.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HBA2	NM_000517.6	c.40G>C	p.Ala14Pro	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.40G>C	p.Ala14Pro	missense_variant	1/3	1	NM_000517.6	ENSP00000251595.6
HBA2	ENST00000484216.1	c.7G>C	p.Ala3Pro	missense_variant	1/2	1		ENSP00000495899.1
HBA2	ENST00000482565.1	n.59G>C		non_coding_transcript_exon_variant	1/2	1
HBA2	ENST00000397806	c.-8G>C		5_prime_UTR_variant	1/3	2		ENSP00000380908.1

Frequencies

GnomAD3 genomes Cov.: 1

GnomAD4 exome AF: 0.00000269 AC: 1 AN: 371084 Hom.: 0 Cov.: 0 AF XY: 0.00 AC XY: 0 AN XY: 194974

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000453

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 1

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:1 Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Aug 10, 2021	It has not been reported in large, multi-ethnic general populations (http://gnomad.broadinstitute.org). In the published literature, the variant has been briefly reported to be associated with an alpha+ thalassemia phenotype in one study (PMID: 26329872 (2015)). Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded conflicting predictions that this variant is deleterious or benign. Based on the available information, we are unable to determine the clinical significance of this variant. -
Likely benign, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Jul 01, 2020	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Uncertain	0.16	D
BayesDel_noAF	Uncertain	-0.010
CADD	Benign	15
DANN	Benign	0.95
Eigen	Benign	-1.1
Eigen_PC	Benign	-1.3
FATHMM_MKL	Benign	0.039	N
M_CAP	Pathogenic	0.61	D
MetaRNN	Uncertain	0.53	D
MetaSVM	Uncertain	-0.26	T
MutationTaster	Benign	1.0	N;N
PrimateAI	Uncertain	0.67	T
PROVEAN	Uncertain	-2.4	N
REVEL	Uncertain	0.58
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.024	D
Vest4		0.42
MutPred		0.20		Loss of MoRF binding (P = 0.0508);
MVP		1.0
MPC		2.8
ClinPred		0.37	T
GERP RS		-7.4
gMVP		0.93

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

Publications

LitVar

Other links and lift over

dbSNP: rs281860609; hg19: chr16-222951;