16-173485-G-T

Position:

• chr16-173485-G-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PM5 PP3_Moderate

The NM_000517.6(HBA2):​c.314G>T​(p.Cys105Phe) 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. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C105R) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 25)
  • Exomes 𝑓: 0.0000014 (1 hom.)
  • Failed GnomAD Quality Control
• Consequence: HBA2 NM_000517.6 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.402

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]

(HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 7 uncertain in NM_000517.6
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr16-173484-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 804215.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.924

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HBA2	NM_000517.6	c.314G>T	p.Cys105Phe	missense_variant	3/3	ENST00000251595.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HBA2	ENST00000251595.11	c.314G>T	p.Cys105Phe	missense_variant	3/3	1	NM_000517.6	P1
	ENST00000702607.1			downstream_gene_variant

Frequencies

GnomAD3 genomes Cov.: 25

GnomAD3 exomes AF: 0.00000806 AC: 2 AN: 248070 Hom.: 1 AF XY: 0.0000149 AC XY: 2 AN XY: 134572

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000580

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.00000137 AC: 2 AN: 1458220 Hom.: 1 Cov.: 33 AF XY: 0.00000276 AC XY: 2 AN XY: 725242

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000448

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 25

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Pathogenic	0.22
CADD	Benign	23
DANN	Benign	0.96
DEOGEN2	Benign	0.14	.;T
Eigen	Benign	-0.17
Eigen_PC	Benign	-0.25
FATHMM_MKL	Benign	0.44	N
M_CAP	Pathogenic	0.56	D
MetaRNN	Pathogenic	0.92	D;D
MetaSVM	Uncertain	0.46	D
MutationTaster	Benign	0.98	D;D
PrimateAI	Uncertain	0.51	T
PROVEAN	Pathogenic	-9.1	D;D
REVEL	Uncertain	0.59
Sift	Pathogenic	0.0	D;D
Sift4G	Uncertain	0.018	D;D
Vest4		0.52
MutPred		0.86		Loss of catalytic residue at H104 (P = 0.1604);.;
MVP		1.0
MPC		2.2
ClinPred		0.58	D
GERP RS		0.96
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
gMVP		0.94

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: rs41417548; hg19: chr16-223484;