chr16-173274-C-T

Position:

• chr16-173274-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM2 PP3_Moderate BP6

The NM_000517.6(HBA2):​c.245C>T​(p.Ser82Phe) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Benign (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S82C) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 23)
• Consequence: HBA2 NM_000517.6 missense
• Clinical Significance: Benign no assertion criteria provided B:1
• Conservation: PhyloP100: 0.989

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 Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.926
• BP6: Variant 16-173274-C-T is Benign according to our data. Variant chr16-173274-C-T is described in ClinVar as [Benign]. Clinvar id is 995797.Status of the report is no_assertion_criteria_provided, 0 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HBA2	NM_000517.6	c.245C>T	p.Ser82Phe	missense_variant	2/3	ENST00000251595.11	NP_000508.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
HBA2	ENST00000251595.11	c.245C>T	p.Ser82Phe	missense_variant	2/3	1	NM_000517.6	ENSP00000251595.6
HBA2	ENST00000484216.1	c.212C>T	p.Ser71Phe	missense_variant	2/2	1		ENSP00000495899.1
HBA2	ENST00000482565.1	n.381C>T		non_coding_transcript_exon_variant	1/2	1
HBA2	ENST00000397806.1	c.149C>T	p.Ser50Phe	missense_variant	2/3	2		ENSP00000380908.1

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 26

GnomAD4 genome Cov.: 23

ClinVar

Significance: Benign

Submissions summary: Benign:1

Revision: no assertion criteria provided

Submissions by phenotype

alpha Thalassemia Benign:1

Benign, no assertion criteria provided

clinical testing

Department of Medical Genetics, Yunnan Provincial Key Laboratory for Birth Defects and Genetic Diseases, The First People’s Hospital of Yunnan Province

Dec 01, 2020

The patient's blood cell counts were unremarkable: hemoglobin (Hb) 142 g/L, mean corpuscular volume (MCV) 89.7 fL, and mean corpuscular hemoglobin (MCH) 31.1 pg. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.14
CADD	Benign	22
DANN	Uncertain	1.0
DEOGEN2	Benign	0.026	.;T
Eigen	Uncertain	0.21
Eigen_PC	Benign	-0.0040
FATHMM_MKL	Benign	0.38	N
M_CAP	Pathogenic	0.86	D
MetaRNN	Pathogenic	0.93	D;D
MetaSVM	Pathogenic	1.0	D
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-5.2	D;D
REVEL	Pathogenic	0.66
Sift	Uncertain	0.0050	D;D
Sift4G	Uncertain	0.044	D;T
Vest4		0.46
MutPred		0.78		Loss of disorder (P = 0.0066);.;
MVP		0.99
MPC		2.4
ClinPred		0.99	D
GERP RS		4.2
gMVP		0.92

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: rs281864864; hg19: chr16-223273;