chr14-54902545-G-C

Position:

• chr14-54902545-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_000161.3(GCH1):​c.119C>G​(p.Pro40Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000862 in 1,392,624 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000086 (0 hom.)
• Consequence: GCH1 NM_000161.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.0610

Genes affected

GCH1 (HGNC:4193): (GTP cyclohydrolase 1) This gene encodes a member of the GTP cyclohydrolase family. The encoded protein is the first and rate-limiting enzyme in tetrahydrobiopterin (BH4) biosynthesis, catalyzing the conversion of GTP into 7,8-dihydroneopterin triphosphate. BH4 is an essential cofactor required by aromatic amino acid hydroxylases as well as nitric oxide synthases. Mutations in this gene are associated with malignant hyperphenylalaninemia and dopa-responsive dystonia. Several alternatively spliced transcript variants encoding different isoforms have been described; however, not all variants give rise to a functional enzyme. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM1: In a chain GTP cyclohydrolase 1 (size 249) in uniprot entity GCH1_HUMAN there are 25 pathogenic changes around while only 3 benign (89%) in NM_000161.3
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.21263087).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GCH1	NM_000161.3	c.119C>G	p.Pro40Arg	missense_variant	1/6	ENST00000491895.7	NP_000152.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GCH1	ENST00000491895.7	c.119C>G	p.Pro40Arg	missense_variant	1/6	1	NM_000161.3	ENSP00000419045	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000862 AC: 12 AN: 1392624 Hom.: 0 Cov.: 32 AF XY: 0.00000727 AC XY: 5 AN XY: 687688

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: 0.0000111

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

GTP cyclohydrolase I deficiency;C1851920:Dystonia 5 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 27, 2021

This sequence change replaces proline with arginine at codon 40 of the GCH1 protein (p.Pro40Arg). The proline residue is moderately conserved and there is a moderate physicochemical difference between proline and arginine. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate insufficient coverage at this position in the ExAC database. This variant has not been reported in the literature in individuals affected with GCH1-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The arginine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect 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. -

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Oct 26, 2022

The c.119C>G (p.P40R) alteration is located in exon 1 (coding exon 1) of the GCH1 gene. This alteration results from a C to G substitution at nucleotide position 119, causing the proline (P) at amino acid position 40 to be replaced by an arginine (R). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.056
BayesDel_addAF	Uncertain	0.023	T
BayesDel_noAF	Benign	-0.20
CADD	Benign	15
DANN	Benign	0.70
DEOGEN2	Benign	0.38	T;T;.;T;.
Eigen	Benign	-1.3
Eigen_PC	Benign	-1.3
FATHMM_MKL	Benign	0.034	N
LIST_S2	Benign	0.52	.;T;T;.;T
M_CAP	Pathogenic	0.98	D
MetaRNN	Benign	0.21	T;T;T;T;T
MetaSVM	Pathogenic	1.2	D
MutationAssessor	Benign	-0.90	N;N;N;N;N
MutationTaster	Benign	1.0	N;N;N;N
PrimateAI	Uncertain	0.76	T
PROVEAN	Benign	-0.050	.;N;N;N;N
REVEL	Uncertain	0.36
Sift	Benign	0.21	.;T;T;T;T
Sift4G	Benign	0.28	T;T;T;T;T
Polyphen		0.0050	B;B;B;B;B
Vest4		0.14
MutPred		0.27		Gain of MoRF binding (P = 0.0106);Gain of MoRF binding (P = 0.0106);Gain of MoRF binding (P = 0.0106);Gain of MoRF binding (P = 0.0106);Gain of MoRF binding (P = 0.0106);
MVP		0.63
MPC		1.1
ClinPred		0.040	T
GERP RS		-0.18
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.1
Varity_R		0.044
gMVP		0.50

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: rs995999325; hg19: chr14-55369263;