rs745756308

Variant names:

• chr2-138013874-T-C
• rs745756308
• NM_006895.3:c.623T>C

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM2 PP3_Strong PP5_Moderate

The NM_006895.3(HNMT):​c.623T>C​(p.Leu208Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,536 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: HNMT NM_006895.3 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:3
• Conservation: PhyloP100: 7.29
• Publications: 6 publications found

Genes affected

HNMT (HGNC:5028): (histamine N-methyltransferase) In mammals, histamine is metabolized by two major pathways: N(tau)-methylation via histamine N-methyltransferase and oxidative deamination via diamine oxidase. This gene encodes the first enzyme which is found in the cytosol and uses S-adenosyl-L-methionine as the methyl donor. In the mammalian brain, the neurotransmitter activity of histamine is controlled by N(tau)-methylation as diamine oxidase is not found in the central nervous system. A common genetic polymorphism affects the activity levels of this gene product in red blood cells. Multiple alternatively spliced transcript variants that encode different proteins have been found for this gene. [provided by RefSeq, Jul 2008]

HNMT Gene-Disease associations (from GenCC):

• intellectual disability, autosomal recessive 51

  Inheritance: AR Classification: STRONG, LIMITED Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• autosomal recessive non-syndromic intellectual disability

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000309081 (HGNC:):

ACMG classification

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.962
• PP5: Variant 2-138013874-T-C is Pathogenic according to our data. Variant chr2-138013874-T-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 219126.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_006895.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HNMT	NM_006895.3	MANE Select	c.623T>C	p.Leu208Pro	missense	Exon 6 of 6	NP_008826.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HNMT	ENST00000280097.5	TSL:1 MANE Select	c.623T>C	p.Leu208Pro	missense	Exon 6 of 6	ENSP00000280097.3
	HNMT	ENST00000410115.5	TSL:5	c.623T>C	p.Leu208Pro	missense	Exon 7 of 7	ENSP00000386940.1
	HNMT	ENST00000894494.1		c.587T>C	p.Leu196Pro	missense	Exon 6 of 6	ENSP00000564553.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 250958 AF XY: 0.00000737

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 FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461536 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727072

African (AFR) AF: 0.00 AC: 0 AN: 33458

American (AMR) AF: 0.00 AC: 0 AN: 44664

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26124

East Asian (EAS) AF: 0.00 AC: 0 AN: 39692

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86244

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53414

Middle Eastern (MID) AF: 0.000173 AC: 1 AN: 5764

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111800

Other (OTH) AF: 0.00 AC: 0 AN: 60376

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ExAC AF: 0.00000824 AC: 1

ClinVar

ClinVar submissions as Germline

Significance: Likely pathogenic

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
3	-	-	Intellectual disability, autosomal recessive 51 (3)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.84
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Pathogenic	0.27
CADD	Uncertain	24
DANN	Pathogenic	1.0
DEOGEN2	Benign	0.41	T
Eigen	Pathogenic	0.80
Eigen_PC	Pathogenic	0.75
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.70	T
M_CAP	Uncertain	0.24	D
MetaRNN	Pathogenic	0.96	D
MetaSVM	Uncertain	-0.035	T
MutationAssessor	Pathogenic	3.1	M
PhyloP100		7.3
PrimateAI	Uncertain	0.63	T
PROVEAN	Pathogenic	-6.5	D
REVEL	Pathogenic	0.73
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.99
MutPred		0.71		Loss of stability (P = 0.015)
MVP		0.92
MPC		0.48
ClinPred		0.92	D
GERP RS		6.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.97
gMVP		0.95
Mutation Taster		=2/98	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs745756308; hg19: chr2-138771444; COSMIC: COSV99698751;