NM_000049.4:c.859G>T

Variant names:

• chr17-3499005-G-T
• rs774323189
• NM_000049.4:c.859G>T

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate

The NM_000049.4(ASPA):​c.859G>T​(p.Ala287Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000479 in 1,461,840 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A287T) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: ASPA NM_000049.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.74
• Publications: 0 publications found

Genes affected

ASPA (HGNC:756): (aspartoacylase) This gene encodes an enzyme that catalyzes the conversion of N-acetyl_L-aspartic acid (NAA) to aspartate and acetate. NAA is abundant in the brain where hydrolysis by aspartoacylase is thought to help maintain white matter. This protein is an NAA scavenger in other tissues. Mutations in this gene cause Canavan disease. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Jul 2008]

SPATA22 (HGNC:30705): (spermatogenesis associated 22) Predicted to be involved in regulation of meiotic cell cycle. Predicted to act upstream of or within several processes, including fertilization; gamete generation; and meiosis I cell cycle process. Predicted to be located in chromosome. [provided by Alliance of Genome Resources, Apr 2022]

SPATA22 Gene-Disease associations (from GenCC):

• infertility disorder

  Inheritance: AR Classification: MODERATE Submitted by: Ambry Genetics

ACMG classification

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 5 uncertain in NM_000049.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-3499005-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 188803.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 48 curated pathogenic missense variants (we use a threshold of 10). The gene has 6 curated benign missense variants. Gene score misZ: 0.47868 (below the threshold of 3.09). Trascript score misZ: 1.2423 (below the threshold of 3.09). GenCC associations: The gene is linked to Canavan disease, mild Canavan disease, severe Canavan disease.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.925

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ASPA	NM_000049.4	c.859G>T	p.Ala287Ser	missense_variant	Exon 6 of 6	ENST00000263080.3	NP_000040.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ASPA	ENST00000263080.3	c.859G>T	p.Ala287Ser	missense_variant	Exon 6 of 6	1	NM_000049.4	ENSP00000263080.2
ASPA	ENST00000456349.6	c.859G>T	p.Ala287Ser	missense_variant	Exon 7 of 7	1		ENSP00000409976.2
SPATA22	ENST00000541913.5	c.-74+14407C>A		intron_variant	Intron 1 of 8	2		ENSP00000441920.1
SPATA22	ENST00000570318.1	c.-74+14606C>A		intron_variant	Intron 1 of 1	2		ENSP00000459147.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000479 AC: 7 AN: 1461840 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727210

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44722

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: 86244

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

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

European-Non Finnish (NFE) AF: 0.00000630 AC: 7 AN: 1111982

Other (OTH) AF: 0.00 AC: 0 AN: 60394

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Jul 15, 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: ASPA c.859G>T (p.Ala287Ser) results in a conservative amino acid change in the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251342 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.859G>T in individuals affected with Canavan Disease and no experimental evidence demonstrating its impact on protein function have been reported. A different variant affecting the same codon has been classified as pathogenic by our lab (c.859G>A, p.Ala287Thr), supporting the critical relevance of codon 287 to ASPA protein function. No submitters have cited clinical-significance assessments for this variant to ClinVar. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.20
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Uncertain	0.10
CADD	Benign	21
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.93	D;D
Eigen	Benign	0.17
Eigen_PC	Benign	0.061
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.77	.;T
M_CAP	Uncertain	0.15	D
MetaRNN	Pathogenic	0.92	D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.5	M;M
PhyloP100		7.7
PrimateAI	Uncertain	0.56	T
PROVEAN	Uncertain	-2.4	N;N
REVEL	Pathogenic	0.71
Sift	Benign	0.049	D;D
Sift4G	Benign	0.10	T;T
Polyphen		0.82	P;P
Vest4		0.59
MutPred		0.86		Gain of disorder (P = 0.0575);Gain of disorder (P = 0.0575);
MVP		0.96
MPC		0.094
ClinPred		0.96	D
GERP RS		3.7
Varity_R		0.54
gMVP		0.82
Mutation Taster		=46/54	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: rs774323189; hg19: chr17-3402299;