11-5227003-C-G

Variant names:

• chr11-5227003-C-G
• rs33930165
• NM_000518.5:c.19G>C

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PM5

The NM_000518.5(HBB):​c.19G>C​(p.Glu7Gln) variant causes a missense 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 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. E7A) 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: 2.63

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 Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr11-5227002-T-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HBB	NM_000518.5	c.19G>C	p.Glu7Gln	missense_variant	Exon 1 of 3	ENST00000335295.4	NP_000509.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HBB	ENST00000335295.4	c.19G>C	p.Glu7Gln	missense_variant	Exon 1 of 3	1	NM_000518.5	ENSP00000333994.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Nov 06, 2024

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

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: HBB c.19G>C (p.Glu7Gln) results in a conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a benign effect of the variant on protein function. The variant was absent in 251156 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.19G>C (also known as p.Glu6Gln and Hb Machida) has been reported in the literature in heterozygous state as a laboratory finding in individuals who were apparently clinically healthy and hematologically normal (Harano_1982). Authors of this study also reported that the sickling test performed on peripheral blood from the carriers was clearly negative, and instability was not demonstrable; in addition, oxygen equilibrium curves of purified Hb Machida were within the normal range, and Hb Machida was synthesized at a nearly normal rate (Harano_1982). Other variants affecting the same codon has been well known to affect HBB function (i.e. E7V aka HbS, E7K aka HbC), supporting the critical relevance of codon 7. A later in vitro functional study demonstrated that the variant did not copolymerize with E7V (HbS) in vitro when mixed in a 1:1 ratio, i.e. it behaved as non-sickling hemoglobins (Adachi_1987). The following publications have been ascertained in the context of this evaluation (PMID: 6129204, 2888754, 29365076). ClinVar contains an entry for this variant (Variation ID: 15243). Based on the evidence outlined above, the variant was classified as uncertain significance. -

HEMOGLOBIN MACHIDA 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	Benign	0.14
BayesDel_addAF	Pathogenic	0.31	D
BayesDel_noAF	Pathogenic	0.20
CADD	Benign	18
DANN	Uncertain	0.98
DEOGEN2	Benign	0.022	T;T;.;T
Eigen	Benign	-0.42
Eigen_PC	Benign	-0.40
FATHMM_MKL	Benign	0.42	N
LIST_S2	Uncertain	0.89	.;D;D;D
M_CAP	Benign	0.083	D
MetaRNN	Uncertain	0.44	T;T;T;T
MetaSVM	Uncertain	-0.23	T
MutationAssessor	Uncertain	2.3	M;M;.;.
PrimateAI	Benign	0.38	T
PROVEAN	Benign	-2.0	N;.;.;N
REVEL	Uncertain	0.44
Sift	Uncertain	0.013	D;.;.;D
Sift4G	Benign	0.18	T;.;.;.
Polyphen		0.011	B;B;.;.
Vest4		0.81
MutPred		0.36		Loss of glycosylation at P6 (P = 0.08);Loss of glycosylation at P6 (P = 0.08);Loss of glycosylation at P6 (P = 0.08);Loss of glycosylation at P6 (P = 0.08);
MVP		0.94
MPC		0.048
ClinPred		0.23	T
GERP RS		5.2
Varity_R		0.58
gMVP		0.50

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: rs33930165; hg19: chr11-5248233;