17-3481798-G-C

Variant names:

• chr17-3481798-G-C
• rs754087904
• NM_000049.4:c.432G>C

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1 PM2 PP2 PP3_Strong

The NM_000049.4(ASPA):​c.432G>C​(p.Lys144Asn) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000697 in 1,433,998 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. K144K) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 7.0e-7 (0 hom.)
• Consequence: ASPA NM_000049.4 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.57
• 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 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 2 uncertain in NM_000049.4
• PM2: Very rare variant in population databases, with high coverage
• 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: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ASPA	NM_000049.4	c.432G>C	p.Lys144Asn	missense_variant, splice_region_variant	Exon 2 of 6	ENST00000263080.3	NP_000040.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ASPA	ENST00000263080.3	c.432G>C	p.Lys144Asn	missense_variant, splice_region_variant	Exon 2 of 6	1	NM_000049.4	ENSP00000263080.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.97e-7 AC: 1 AN: 1433998 Hom.: 0 Cov.: 29 AF XY: 0.00000140 AC XY: 1 AN XY: 713262

⚠️ 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: 32958

American (AMR) AF: 0.00 AC: 0 AN: 43652

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25796

East Asian (EAS) AF: 0.00 AC: 0 AN: 39368

South Asian (SAS) AF: 0.00 AC: 0 AN: 84408

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52776

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 4976

European-Non Finnish (NFE) AF: 9.17e-7 AC: 1 AN: 1090790

Other (OTH) AF: 0.00 AC: 0 AN: 59274

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.70
BayesDel_addAF	Pathogenic	0.17	D
BayesDel_noAF	Uncertain	0.0
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.84	D;D
Eigen	Pathogenic	0.83
Eigen_PC	Pathogenic	0.82
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.88	.;D
M_CAP	Uncertain	0.19	D
MetaRNN	Pathogenic	0.92	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.6	M;M
PhyloP100		7.6
PrimateAI	Uncertain	0.59	T
PROVEAN	Benign	-2.0	N;N
REVEL	Pathogenic	0.78
Sift	Uncertain	0.013	D;D
Sift4G	Uncertain	0.030	D;D
Polyphen		0.99	D;D
Vest4		0.70
MutPred		0.75		Loss of ubiquitination at K144 (P = 0.0283);Loss of ubiquitination at K144 (P = 0.0283);
MVP		1.0
MPC		0.43
ClinPred		0.98	D
GERP RS		5.6
Varity_R		0.74
gMVP		0.87

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.95		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.95		Position offset: 0

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs754087904; hg19: chr17-3385092;