chr20-34281051-C-T

Variant names:

• chr20-34281051-C-T
• rs2035983583
• NM_000687.4:c.1282G>A

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PM2 BP4

The NM_000687.4(AHCY):​c.1282G>A​(p.Asp428Asn) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,822 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 (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: AHCY NM_000687.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.69
• Publications: 0 publications found

Genes affected

AHCY (HGNC:343): (adenosylhomocysteinase) S-adenosylhomocysteine hydrolase belongs to the adenosylhomocysteinase family. It catalyzes the reversible hydrolysis of S-adenosylhomocysteine (AdoHcy) to adenosine (Ado) and L-homocysteine (Hcy). Thus, it regulates the intracellular S-adenosylhomocysteine (SAH) concentration thought to be important for transmethylation reactions. Deficiency in this protein is one of the different causes of hypermethioninemia. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jun 2009]

AHCY Gene-Disease associations (from GenCC):

• hypermethioninemia with deficiency of S-adenosylhomocysteine hydrolase

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: ClinGen, Labcorp Genetics (formerly Invitae), Orphanet

ENSG00000250917 (HGNC:):

ACMG classification

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.3239032).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000687.4. 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
	AHCY	NM_000687.4	MANE Select	c.1282G>A	p.Asp428Asn	missense	Exon 10 of 10	NP_000678.1	A0A384MTQ3
	AHCY	NM_001322086.2		c.1288G>A	p.Asp430Asn	missense	Exon 10 of 10	NP_001309015.1
	AHCY	NM_001362750.2		c.1282G>A	p.Asp428Asn	missense	Exon 10 of 11	NP_001349679.1	A0A384MTQ3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	AHCY	ENST00000217426.7	TSL:1 MANE Select	c.1282G>A	p.Asp428Asn	missense	Exon 10 of 10	ENSP00000217426.2	P23526-1
	AHCY	ENST00000538132.1	TSL:2	c.1198G>A	p.Asp400Asn	missense	Exon 10 of 10	ENSP00000442820.1	P23526-2
	AHCY	ENST00000480653.5	TSL:2	n.1430G>A		non_coding_transcript_exon	Exon 9 of 9

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461822 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727202

⚠️ 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: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44710

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86242

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53394

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1112000

Other (OTH) AF: 0.0000166 AC: 1 AN: 60394

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000312 Hom.: 0

Bravo AF: 0.00000378

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
-	1	-	Hypermethioninemia with deficiency of S-adenosylhomocysteine hydrolase (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.093
BayesDel_addAF	Benign	-0.060	T
BayesDel_noAF	Benign	-0.32
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.61	D
Eigen	Benign	0.16
Eigen_PC	Uncertain	0.30
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.96	D
M_CAP	Benign	0.029	D
MetaRNN	Benign	0.32	T
MetaSVM	Benign	-0.35	T
MutationAssessor	Benign	1.8	L
PhyloP100		7.7
PrimateAI	Uncertain	0.67	T
PROVEAN	Uncertain	-2.7	D
REVEL	Uncertain	0.35
Sift	Benign	0.088	T
Sift4G	Benign	0.079	T
Polyphen		0.0060	B
Vest4		0.44
MutPred		0.52		Loss of phosphorylation at Y430 (P = 0.0666)
MVP		0.83
MPC		0.51
ClinPred		0.95	D
GERP RS		4.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.41
gMVP		0.77
Mutation Taster		=42/58	disease causing

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: rs2035983583; hg19: chr20-32868857;