16-88856762-T-C

Position:

• chr16-88856762-T-C

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PP3_Strong PP5_Very_Strong

The ENST00000268695.10(GALNS):​c.116A>G​(p.Asp39Gly) variant causes a missense change. The variant allele was found at a frequency of 0.00000438 in 1,371,062 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. D39Y) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 28)
  • Exomes 𝑓: 0.0000044 (0 hom.)
• Consequence: GALNS ENST00000268695.10 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 3.64

Genes affected

GALNS (HGNC:4122): (galactosamine (N-acetyl)-6-sulfatase) This gene encodes N-acetylgalactosamine-6-sulfatase which is a lysosomal exohydrolase required for the degradation of the glycosaminoglycans, keratan sulfate, and chondroitin 6-sulfate. Sequence alterations including point, missense and nonsense mutations, as well as those that affect splicing, result in a deficiency of this enzyme. Deficiencies of this enzyme lead to Morquio A syndrome, a lysosomal storage disorder. [provided by RefSeq, Jul 2008]

TRAPPC2L (HGNC:30887): (trafficking protein particle complex subunit 2L) This gene encodes a protein that interacts with the tethering factor trafficking protein particle (TRAPP complex). TRAPP complexes mediate the contact between vescicles and target membranes, and thus, are involved in vescicle-mediated transport of proteins and lipids. The encoded protein is related to the X-linked trafficking protein particle complex 2. A related pseudogene is located on the X chromosome. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Jan 2016]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 11 uncertain in ENST00000268695.10
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.966
• PP5: Variant 16-88856762-T-C is Pathogenic according to our data. Variant chr16-88856762-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 870481.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GALNS	NM_000512.5	c.116A>G	p.Asp39Gly	missense_variant	1/14	ENST00000268695.10	NP_000503.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GALNS	ENST00000268695.10	c.116A>G	p.Asp39Gly	missense_variant	1/14	1	NM_000512.5	ENSP00000268695	P1

Frequencies

GnomAD3 genomes Cov.: 28

GnomAD4 exome AF: 0.00000438 AC: 6 AN: 1371062 Hom.: 0 Cov.: 33 AF XY: 0.00000443 AC XY: 3 AN XY: 677622

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: 0.0000126

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000467

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 28

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Mucopolysaccharidosis, MPS-IV-A Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Foundation for Research in Genetics and Endocrinology, FRIGE's Institute of Human Genetics	-	A homozygous missense variation in exon 1 of the GALNS gene that results in the amino acid substitution of Glycine for Aspartic acid at codon 39 was detected. The observed variant c.116A>G (p.Asp39Gly) has not been reported in the 1000 genomes and ExAC databases. The in silico prediction of the variant is damaging by LRT and MutationTaster2. The reference codon is conserved across species. In summary, the variant meets our criteria to be classified as likely pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Feb 14, 2023	This sequence change replaces aspartic acid, which is acidic and polar, with glycine, which is neutral and non-polar, at codon 39 of the GALNS protein (p.Asp39Gly). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with mucopolysaccharidosis type IVA (PMID: 35729508). ClinVar contains an entry for this variant (Variation ID: 870481). 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 GALNS protein function. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.47	D
BayesDel_noAF	Pathogenic	0.44
CADD	Pathogenic	32
DANN	Uncertain	0.98
DEOGEN2	Pathogenic	0.96	D;.;T
Eigen	Pathogenic	0.71
Eigen_PC	Uncertain	0.52
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.98	D;T;T
M_CAP	Pathogenic	0.99	D
MetaRNN	Pathogenic	0.97	D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.8	H;.;.
MutationTaster	Benign	1.0	D;D;D;D;D
PrimateAI	Pathogenic	0.90	D
PROVEAN	Pathogenic	-5.9	D;D;D
REVEL	Pathogenic	0.93
Sift	Uncertain	0.0060	D;D;D
Sift4G	Uncertain	0.0060	D;D;D
Polyphen		1.0	D;.;.
Vest4		0.70
MutPred		0.82		Loss of stability (P = 0.0137);Loss of stability (P = 0.0137);Loss of stability (P = 0.0137);
MVP		1.0
MPC		0.54
ClinPred		0.99	D
GERP RS		3.5
Varity_R		0.98
gMVP		0.99

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: rs1967935882; hg19: chr16-88923170;