rs1555620800

Positions:

• chr17-44007592-T-A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_153006.3(NAGS):​c.1270T>A​(p.Tyr424Asn) variant causes a missense, splice region change. The variant allele was found at a frequency of 0.0000131 in 152,158 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 predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: 𝑓 0.000013 (0 hom., cov: 32)
• Consequence: NAGS NM_153006.3 missense, splice_region
• Scores: Splicing: ADA: 0.7388
• Clinical Significance: Uncertain significance criteria provided, single submitter U:2
• Conservation: PhyloP100: 5.21

Genes affected

NAGS (HGNC:17996): (N-acetylglutamate synthase) The N-acetylglutamate synthase gene encodes a mitochondrial enzyme that catalyzes the formation of N-acetylglutamate (NAG) from glutamate and acetyl coenzyme-A. NAG is a cofactor of carbamyl phosphate synthetase I (CPSI), the first enzyme of the urea cycle in mammals. This gene may regulate ureagenesis by altering NAG availability and, thereby, CPSI activity. Deficiencies in N-acetylglutamate synthase have been associated with hyperammonemia. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a domain N-acetyltransferase (size 151) in uniprot entity NAGS_HUMAN there are 13 pathogenic changes around while only 0 benign (100%) in NM_153006.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.933

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NAGS	NM_153006.3	c.1270T>A	p.Tyr424Asn	missense_variant, splice_region_variant	6/7	ENST00000293404.8	NP_694551.1
NAGS	XM_011524439.2	c.772T>A	p.Tyr258Asn	missense_variant, splice_region_variant	6/7		XP_011522741.1
NAGS	XM_011524438.2	c.1268+98T>A		intron_variant			XP_011522740.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
NAGS	ENST00000293404.8	c.1270T>A	p.Tyr424Asn	missense_variant, splice_region_variant	6/7	1	NM_153006.3	ENSP00000293404	P1
NAGS	ENST00000589767.1	c.1201T>A	p.Tyr401Asn	missense_variant	6/7	2		ENSP00000465408
NAGS	ENST00000592915.1	n.1158T>A		splice_region_variant, non_coding_transcript_exon_variant	3/4	2

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152158 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 30

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152158 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74338

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.0000655

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000624 Hom.: 0

Bravo AF: 0.0000189

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, single submitter

Submissions by phenotype

Hyperammonemia, type III Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Aug 13, 2021	This sequence change replaces tyrosine with asparagine at codon 424 of the NAGS protein (p.Tyr424Asn). The tyrosine residue is highly conserved and there is a large physicochemical difference between tyrosine and asparagine. This variant is not present in population databases (ExAC no frequency). This missense change has been observed in individual(s) with clinical features of NAGS-related conditions (Invitae). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -
Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Oct 05, 2021	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.57
BayesDel_addAF	Pathogenic	0.48	D
BayesDel_noAF	Pathogenic	0.45
CADD	Pathogenic	32
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.95	D;.
Eigen	Pathogenic	0.82
Eigen_PC	Pathogenic	0.76
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Uncertain	0.90	D;T
M_CAP	Pathogenic	0.73	D
MetaRNN	Pathogenic	0.93	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.4	M;.
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.75	T
PROVEAN	Pathogenic	-6.6	D;.
REVEL	Pathogenic	0.88
Sift	Uncertain	0.0010	D;.
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;.
Vest4		0.96
MutPred		0.74		Loss of phosphorylation at Y424 (P = 0.0341);.;
MVP		0.99
MPC		2.3
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.98
gMVP		0.90

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.74
dbscSNV1_RF	Benign	0.44
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555620800; hg19: chr17-42084960;