11-5226669-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1PM2PM5

The NM_000518.5(HBB):c.223G>A(p.Gly75Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000372 in 1,614,020 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G75D) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000021 ( 0 hom. )

Consequence

HBB
NM_000518.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:3

Conservation

PhyloP100: 7.32

Variant links:

Genes affected

HBB (HGNC:4827): (hemoglobin subunit beta) The alpha (HBA) and beta (HBB) loci determine the structure of the 2 types of polypeptide chains in adult hemoglobin, Hb A. The normal adult hemoglobin tetramer consists of two alpha chains and two beta chains. Mutant beta globin causes sickle cell anemia. Absence of beta chain causes beta-zero-thalassemia. Reduced amounts of detectable beta globin causes beta-plus-thalassemia. The order of the genes in the beta-globin cluster is 5'-epsilon -- gamma-G -- gamma-A -- delta -- beta--3'. [provided by RefSeq, Jul 2008]

HBB links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

PM1

In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 5 benign, 14 uncertain in NM_000518.5

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr11-5226669-C-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
HBB	NM_000518.5 linkuse as main transcript	c.223G>A	p.Gly75Ser	missense_variant	2/3	ENST00000335295.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
HBB	ENST00000335295.4 linkuse as main transcript	c.223G>A	p.Gly75Ser	missense_variant	2/3	1	NM_000518.5	P1

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

152142

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000441

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000119

AC:

AN:

251428

Hom.:

AF XY:

0.0000147

AC XY:

AN XY:

135884

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

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:

0.0000264

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000205

AC:

AN:

1461878

Hom.:

Cov.:

AF XY:

0.00000275

AC XY:

AN XY:

727242

show subpopulations

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:

0.00000270

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.0000197

AC:

AN:

152142

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74320

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000441

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.00000756

ExAC

AF:

0.0000165

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not specified

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Sep 09, 2019

Variant summary: HBB c.223G>A (p.Gly75Ser) results in a non-conservative amino acid change located in the Globin domain (IPR000971) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 1.2e-05 in 251428 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.223G>A has been reported in the literature in individuals predicted to be carriers for beta-thalassemia (Giambona_2008,2011, Mosca_2008), however, to our knowledge, the variant has not been reported in individuals affected by the disease. These reports do not provide unequivocal conclusions about association of the variant with Hemoglobinopathy. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. No other clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014. Based on the evidence outlined above, the variant was classified as uncertain significance. -

beta Thalassemia

Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

Natera, Inc.

Sep 16, 2020

- -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Quest Diagnostics Nichols Institute San Juan Capistrano

Jan 10, 2023

The HBB c.223G>A (p.Gly75Ser) variant, also known as Hb Kokomo has been reported in individuals with normal hematological indices (PMID: 18603555 (2008)), as well as in individuals predicted to be carriers of beta-thalassemia (PMIDs: 21353607 (2011) and 18486569 (2008)). While the variant is described as having normal stability, heterozygosity for this variant is associated with mild hemolytic anemia and reticulocytosis. Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is damaging. Based on the available information, we are unable to determine the clinical significance of this variant. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.68

BayesDel_addAF

Pathogenic

0.23

BayesDel_noAF

Uncertain

0.11

Cadd

Benign

Dann

Uncertain

1.0

DEOGEN2

Benign

0.11

T;T;.;T

Eigen

Uncertain

0.33

Eigen_PC

Uncertain

0.27

FATHMM_MKL

Pathogenic

0.98

M_CAP

Pathogenic

0.46

MetaRNN

Uncertain

0.73

D;D;D;D

MetaSVM

Uncertain

0.76

MutationAssessor

Uncertain

2.8

M;M;.;.

MutationTaster

Benign

1.0

PrimateAI

Benign

0.45

PROVEAN

Benign

-2.2

N;.;.;D

REVEL

Uncertain

0.64

Sift

Uncertain

0.0020

D;.;.;D

Sift4G

Uncertain

0.015

D;.;.;.

Polyphen

0.65

P;P;.;.

Vest4

0.58

MutPred

0.52

Gain of loop (P = 0.1069);Gain of loop (P = 0.1069);Gain of loop (P = 0.1069);Gain of loop (P = 0.1069);

MVP

0.91

MPC

0.13

ClinPred

0.85

GERP RS

5.1

Varity_R

0.61

gMVP

0.84

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over