rs34492931

Variant names:

• chr16-176954-A-G
• rs34492931
• NM_000558.5:c.121A>G

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_000558.5(HBA1):​c.121A>G​(p.Lys41Glu) 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 other (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. K41N) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 0.0000010 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: HBA1 NM_000558.5 missense
• Clinical Significance: other no assertion criteria provided O:1
• Conservation: PhyloP100: 1.46
• Publications: 1 publications found

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]

HBA1 Gene-Disease associations (from GenCC):

• alpha thalassemia spectrum

  Inheritance: AR, SD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics
• erythrocytosis, familial, 7

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
• 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
• methemoglobinemia, alpha type

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen
• Heinz body anemia

  Inheritance: AR Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)

ENSG00000294436 (HGNC:):

ACMG classification

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 17 uncertain in NM_000558.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.977

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HBA1	NM_000558.5	c.121A>G	p.Lys41Glu	missense_variant	Exon 2 of 3	ENST00000320868.9	NP_000549.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HBA1	ENST00000320868.9	c.121A>G	p.Lys41Glu	missense_variant	Exon 2 of 3	1	NM_000558.5	ENSP00000322421.5

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.00000101 AC: 1 AN: 986362 Hom.: 0 Cov.: 13 AF XY: 0.00 AC XY: 0 AN XY: 504318

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 23720

American (AMR) AF: 0.00 AC: 0 AN: 37668

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 22544

East Asian (EAS) AF: 0.00 AC: 0 AN: 35014

South Asian (SAS) AF: 0.00 AC: 0 AN: 74220

European-Finnish (FIN) AF: 0.0000268 AC: 1 AN: 37292

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 3274

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 708082

Other (OTH) AF: 0.00 AC: 0 AN: 44548

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 30

ClinVar

Significance: other

Submissions summary: Other:1

Revision: no assertion criteria provided

Submissions by phenotype

HEMOGLOBIN KARIYA Other:1

Jul 20, 2016

OMIM

Significance: other

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.93
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.29
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Benign	0.33	T;.
Eigen	Uncertain	0.31
Eigen_PC	Uncertain	0.35
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.97	D;D
M_CAP	Pathogenic	0.97	D
MetaRNN	Pathogenic	0.98	D;D
MetaSVM	Pathogenic	0.90	D
PhyloP100		1.5
PrimateAI	Uncertain	0.68	T
PROVEAN	Uncertain	-3.9	D;D
REVEL	Pathogenic	0.89
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0010	D;D
Vest4		0.71
MutPred		0.87		Loss of methylation at K41 (P = 0.0059);.;
MVP		0.99
ClinPred		1.0	D
GERP RS		4.5
PromoterAI		0.034	Neutral
Varity_R		0.97
gMVP		0.96

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs34492931; hg19: chr16-226953;