rs34021271

chr16-177377-C-CT

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PVS1_Strong PM2 PP5

The NM_000558.5(HBA1):c.396dup(p.Val133CysfsTer45) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (no stars). Synonymous variant affecting the same amino acid position (i.e. S132S) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: HBA1 NM_000558.5 frameshift
• Clinical Significance: Pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: -1.69

Genes affected

HBA1 (HGNC:4823): (hemoglobin subunit alpha 1) 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]

(HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. There are 7 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 16-177377-C-CT is Pathogenic according to our data. Variant chr16-177377-C-CT is described in ClinVar as [Pathogenic]. Clinvar id is 869325.Status of the report is no_assertion_criteria_provided, 0 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HBA1	NM_000558.5	c.396dup	p.Val133CysfsTer45	frameshift_variant	3/3	ENST00000320868.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HBA1	ENST00000320868.9	c.396dup	p.Val133CysfsTer45	frameshift_variant	3/3	1	NM_000558.5	P1
HBA1	ENST00000472694.1	n.532dup		non_coding_transcript_exon_variant	2/2	1
	ENST00000702457.1	n.113_114insA		non_coding_transcript_exon_variant	1/1
HBA1	ENST00000397797.1	c.300dup	p.Val101CysfsTer45	frameshift_variant	3/3	2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: no assertion criteria provided

Submissions by phenotype

alpha Thalassemia Pathogenic:1

Pathogenic, no assertion criteria provided

curation

The ITHANET community portal, The Cyprus Institute of Neurology and Genetics

Nov 25, 2019

- -

Computational scores

Source: dbNSFP v4.3

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: rs34021271; hg19: chr16-227376;