18-36187672-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_017947.4(MOCOS):c.133C>T(p.Arg45Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000166 in 1,262,966 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. R45H) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000017 (0 hom.)
• Consequence: MOCOS NM_017947.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.84

Genes affected

MOCOS (HGNC:18234): (molybdenum cofactor sulfurase) This gene encodes an enzyme that sulfurates the molybdenum cofactor which is required for activation of the xanthine dehydrogenase (XDH) and aldehyde oxidase (AO) enzymes. XDH catalyzes the conversion of hypoxanthine to uric acid via xanthine, as well as the conversion of allopurinol to oxypurinol, and pyrazinamide to 5-hydroxy pyrazinamide. Mutations in this gene cause the metabolic disorder classical xanthinuria type II which is characterized by the loss of XDH/XO and AO enzyme activity, decreased levels of uric acid in the urine, increased levels of xanthine and hypoxanthine in the serum and urine, formation of xanthine stones in the urinary tract, and myositis due to tissue deposition of xanthine. [provided by RefSeq, Apr 2017]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MOCOS	NM_017947.4	c.133C>T	p.Arg45Cys	missense_variant	1/15	ENST00000261326.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MOCOS	ENST00000261326.6	c.133C>T	p.Arg45Cys	missense_variant	1/15	1	NM_017947.4	P1

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152206 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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: 0.0000294

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.0000171 AC: 19 AN: 1110760 Hom.: 0 Cov.: 33 AF XY: 0.0000133 AC XY: 7 AN XY: 528206

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000203

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152206 Hom.: 0 Cov.: 33 AF XY: 0.0000134 AC XY: 1 AN XY: 74368

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000294

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000151

ExAC AF: 0.00000953 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Xanthinuria type II Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Sep 13, 2022

This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 45 of the MOCOS protein (p.Arg45Cys). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This variant has not been reported in the literature in individuals affected with MOCOS-related conditions. ClinVar contains an entry for this variant (Variation ID: 1416833). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt MOCOS protein function. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.65
BayesDel_addAF	Benign	-0.020	T
BayesDel_noAF	Benign	-0.27
Cadd	Pathogenic	33
Dann	Uncertain	1.0
DEOGEN2	Benign	0.26	T
Eigen	Uncertain	0.21
Eigen_PC	Benign	0.21
FATHMM_MKL	Uncertain	0.83	D
LIST_S2	Uncertain	0.89	D
M_CAP	Uncertain	0.14	D
MetaRNN	Uncertain	0.66	D
MetaSVM	Benign	-1.0	T
MutationAssessor	Uncertain	2.2	M
MutationTaster	Benign	0.99	D
PrimateAI	Uncertain	0.77	T
PROVEAN	Pathogenic	-5.9	D
REVEL	Benign	0.23
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.57
MutPred		0.44		Loss of MoRF binding (P = 0.0247);
MVP		0.47
MPC		0.47
ClinPred		0.99	D
GERP RS		3.3
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.6
Varity_R		0.91
gMVP		0.65

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

Publications

LitVar

Other links and lift over

dbSNP: rs759622598; hg19: chr18-33767635;