9-6554679-G-C

Variant names:

• chr9-6554679-G-C
• rs751114163
• NM_000170.3:c.2305C>G

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Strong

The NM_000170.3(GLDC):​c.2305C>G​(p.Pro769Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. P769S) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: GLDC NM_000170.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.57
• Publications: 0 publications found

Genes affected

GLDC (HGNC:4313): (glycine decarboxylase) Degradation of glycine is brought about by the glycine cleavage system, which is composed of four mitochondrial protein components: P protein (a pyridoxal phosphate-dependent glycine decarboxylase), H protein (a lipoic acid-containing protein), T protein (a tetrahydrofolate-requiring enzyme), and L protein (a lipoamide dehydrogenase). The protein encoded by this gene is the P protein, which binds to glycine and enables the methylamine group from glycine to be transferred to the T protein. Defects in this gene are a cause of nonketotic hyperglycinemia (NKH).[provided by RefSeq, Jan 2010]

GLDC Gene-Disease associations (from GenCC):

• glycine encephalopathy

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Myriad Women’s Health, Labcorp Genetics (formerly Invitae), ClinGen
• glycine encephalopathy 1

  Inheritance: AR Classification: DEFINITIVE Submitted by: G2P
• infantile glycine encephalopathy

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• neonatal glycine encephalopathy

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• atypical glycine encephalopathy

  Inheritance: Unknown Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PM1: In a hotspot region, there are 13 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 4 uncertain in NM_000170.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr9-6554678-G-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 56071.Status of the report is no_assertion_criteria_provided, 0 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.956

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GLDC	NM_000170.3	c.2305C>G	p.Pro769Ala	missense_variant	Exon 19 of 25	ENST00000321612.8	NP_000161.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GLDC	ENST00000321612.8	c.2305C>G	p.Pro769Ala	missense_variant	Exon 19 of 25	1	NM_000170.3	ENSP00000370737.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Glycine encephalopathy Uncertain:1

Nov 25, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is not present in population databases (gnomAD no frequency). This sequence change replaces proline, which is neutral and non-polar, with alanine, which is neutral and non-polar, at codon 769 of the GLDC protein (p.Pro769Ala). This variant has not been reported in the literature in individuals affected with GLDC-related conditions. 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 not expected to disrupt GLDC protein function. This variant disrupts the p.Pro769 amino acid residue in GLDC. Other variant(s) that disrupt this residue have been observed in individuals with GLDC-related conditions (PMID: 16450403, 27362913), which suggests that this may be a clinically significant amino acid residue. 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	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.36
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.76	D;.;.;.
Eigen	Pathogenic	0.93
Eigen_PC	Pathogenic	0.89
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D;T;D;D
M_CAP	Pathogenic	0.51	D
MetaRNN	Pathogenic	0.96	D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.1	M;.;.;.
PhyloP100		9.6
PrimateAI	Uncertain	0.74	T
PROVEAN	Pathogenic	-7.6	D;.;.;.
REVEL	Pathogenic	0.87
Sift	Uncertain	0.0020	D;.;.;.
Sift4G	Uncertain	0.0060	D;.;.;.
Polyphen		1.0	D;.;.;.
Vest4		0.85
MutPred		0.81		Loss of disorder (P = 0.0621);.;.;.;
MVP		0.99
MPC		0.31
ClinPred		1.0	D
GERP RS		5.4
PromoterAI		0.0092	Neutral
Varity_R		0.84
gMVP		0.94
Mutation Taster		=27/73	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		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: rs751114163; hg19: chr9-6554679;