11-5226780-A-C

Variant names:

• chr11-5226780-A-C
• rs33994623
• NM_000518.5:c.112T>G

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PM5 PP3_Strong

The NM_000518.5(HBB):​c.112T>G​(p.Trp38Gly) variant causes a missense change. 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 Uncertain significance (★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Likely benign in UniProt. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. W38R) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: HBB NM_000518.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1 O:1
• Conservation: PhyloP100: 5.72

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr11-5226779-C-A is described in Lovd as [Likely_pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.969

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HBB	NM_000518.5	c.112T>G	p.Trp38Gly	missense_variant	Exon 2 of 3	ENST00000335295.4	NP_000509.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HBB	ENST00000335295.4	c.112T>G	p.Trp38Gly	missense_variant	Exon 2 of 3	1	NM_000518.5	ENSP00000333994.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 36

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Mar 01, 2024

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The HBB c.112T>G (p.Trp38Gly) variant (also known as Hb Howick and W37G) has been reported in the published literature in a heterozygous, unaffected individual with normal hematological results (PMID: 8144352 (1993)). Functional studies indicated that this variant has increased oxygen affinity, reduced cooperativity, impairs 2,3-DPG binding and the stability of the deoxy form, however, has overall normal protein stability (PMID: 8144352 (1993), 9521756 (1998)). When this variant occurs on the same chromosome as the Hb S pathogenic variant, it is known as Hb C Ndjamena, c.[20A>T;112T>G] (PMID: 23457306 (2013), 34113458 (2021)), and when found with Hb S in trans, may reduce the severity of sickle cell disease. The Hb Howick variant has not been reported in large, multi-ethnic general populations (Genome Aggregation Database, http://gnomad.broadinstitute.org). Based on the available information, we are unable to determine the clinical significance of this variant. Testing affected family members could help clarify the clinical significance of this variant. Genetic counseling is recommended. -

HEMOGLOBIN HOWICK Other:1

Dec 12, 2017

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	0.94
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.37
CADD	Pathogenic	26
DANN	Uncertain	0.98
DEOGEN2	Benign	0.060	T;T;.;T
Eigen	Pathogenic	0.78
Eigen_PC	Pathogenic	0.73
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.97	.;D;D;D
M_CAP	Pathogenic	0.41	D
MetaRNN	Pathogenic	0.97	D;D;D;D
MetaSVM	Uncertain	0.75	D
MutationAssessor	Pathogenic	3.6	H;H;.;.
PrimateAI	Uncertain	0.78	T
PROVEAN	Pathogenic	-12	D;.;.;D
REVEL	Pathogenic	0.92
Sift	Uncertain	0.0030	D;.;.;D
Sift4G	Uncertain	0.0020	D;.;.;.
Polyphen		1.0	D;D;.;.
Vest4		0.80
MutPred		0.82		Loss of catalytic residue at W38 (P = 0.0177);Loss of catalytic residue at W38 (P = 0.0177);Loss of catalytic residue at W38 (P = 0.0177);Loss of catalytic residue at W38 (P = 0.0177);
MVP		0.97
MPC		0.31
ClinPred		1.0	D
GERP RS		5.1
Varity_R		0.86
gMVP		0.80

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: rs33994623; hg19: chr11-5248010;