NM_000190.4:c.23C>T

Variant names:

• chr11-119085056-C-T
• rs1341756409
• NM_000190.4:c.23C>T

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_000190.4(HMBS):​c.23C>T​(p.Ala8Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,320 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 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. A8T) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: HMBS NM_000190.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.42
• Publications: 0 publications found

Genes affected

HMBS (HGNC:4982): (hydroxymethylbilane synthase) This gene encodes a member of the hydroxymethylbilane synthase superfamily. The encoded protein is the third enzyme of the heme biosynthetic pathway and catalyzes the head to tail condensation of four porphobilinogen molecules into the linear hydroxymethylbilane. Mutations in this gene are associated with the autosomal dominant disease acute intermittent porphyria. Alternatively spliced transcript variants encoding different isoforms have been described. [provided by RefSeq, Jul 2008]

HMBS Gene-Disease associations (from GenCC):

• acute intermittent porphyria

  Inheritance: AD, SD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, ClinGen, Orphanet, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.19464234).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000190.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HMBS	NM_000190.4	MANE Select	c.23C>T	p.Ala8Val	missense	Exon 1 of 14	NP_000181.2
	HMBS	NM_001425052.1		c.-120C>T		5_prime_UTR_premature_start_codon_gain	Exon 1 of 14	NP_001411981.1	P08397-2
	HMBS	NM_001425053.1		c.-96C>T		5_prime_UTR_premature_start_codon_gain	Exon 1 of 14	NP_001411982.1	P08397-2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HMBS	ENST00000652429.1	MANE Select	c.23C>T	p.Ala8Val	missense	Exon 1 of 14	ENSP00000498786.1	P08397-1
	HMBS	ENST00000545621.5	TSL:1	n.23C>T		non_coding_transcript_exon	Exon 1 of 10	ENSP00000444849.1	F5H4X2
	HMBS	ENST00000545901.5	TSL:1	n.176C>T		non_coding_transcript_exon	Exon 1 of 3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461320 Hom.: 0 Cov.: 43 AF XY: 0.00000413 AC XY: 3 AN XY: 726986

⚠️ 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: 33476

American (AMR) AF: 0.00 AC: 0 AN: 44708

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39678

South Asian (SAS) AF: 0.00 AC: 0 AN: 86252

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53076

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1111860

Other (OTH) AF: 0.00 AC: 0 AN: 60370

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000000000000888178), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 31

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
-	1	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Uncertain	0.16	D
BayesDel_noAF	Uncertain	-0.010
CADD	Benign	22
DANN	Uncertain	1.0
DEOGEN2	Benign	0.31	T
Eigen	Benign	-0.44
Eigen_PC	Benign	-0.40
FATHMM_MKL	Benign	0.39	N
M_CAP	Pathogenic	0.41	D
MetaRNN	Benign	0.19	T
MetaSVM	Pathogenic	1.2	D
MutationAssessor	Benign	0.90	L
PhyloP100		1.4
PrimateAI	Benign	0.35	T
PROVEAN	Benign	-0.19	N
REVEL	Uncertain	0.39
Sift	Benign	0.054	T
Sift4G	Benign	0.17	T
Polyphen		0.15	B
Vest4		0.25
MutPred		0.26		Loss of helix (P = 0.0104)
MVP		0.71
MPC		0.68
ClinPred		0.88	D
GERP RS		3.9
PromoterAI		-0.011	Neutral
Varity_R		0.086
Mutation Taster		=93/7	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		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: rs1341756409; hg19: chr11-118955766;