rs1555358380

Variant names:

• chr14-54844066-C-T
• rs1555358380
• NM_000161.3:c.704G>A

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM1 PM2 PP2

The NM_000161.3(GCH1):​c.704G>A​(p.Arg235Gln) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. 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. R235W) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: GCH1 NM_000161.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 6.05
• Publications: 0 publications found

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]

GCH1 Gene-Disease associations (from GenCC):

• dystonia 5

  Inheritance: AD, AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Ambry Genetics, Orphanet, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), G2P
• GTP cyclohydrolase I deficiency with hyperphenylalaninemia

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, Orphanet, G2P
• GTP cyclohydrolase I deficiency

  Inheritance: SD, AD Classification: DEFINITIVE Submitted by: ClinGen, Illumina

ACMG classification

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_000161.3
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 30 curated pathogenic missense variants (we use a threshold of 10). The gene has 1 curated benign missense variants. Gene score misZ: 1.5191 (below the threshold of 3.09). Trascript score misZ: 0.62455 (below the threshold of 3.09). GenCC associations: The gene is linked to GTP cyclohydrolase I deficiency, dystonia 5, GTP cyclohydrolase I deficiency with hyperphenylalaninemia.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GCH1	NM_000161.3	c.704G>A	p.Arg235Gln	missense_variant	Exon 6 of 6	ENST00000491895.7	NP_000152.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GCH1	ENST00000491895.7	c.704G>A	p.Arg235Gln	missense_variant	Exon 6 of 6	1	NM_000161.3	ENSP00000419045.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

Alfa AF: 0.0000312 Hom.: 0

Bravo AF: 0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Dystonia 5 Uncertain:3

Sep 10, 2020

Institute of Human Genetics, University of Leipzig Medical Center

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was identified as homozygous. -

Jan 17, 2017

Undiagnosed Diseases Network, NIH

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Dec 18, 2024

Genomic Medicine Center of Excellence, King Faisal Specialist Hospital and Research Centre

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Uncertain:1

Jul 18, 2024

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge; This variant is associated with the following publications: (PMID: 33903016) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.59
BayesDel_addAF	Pathogenic	0.29	D
BayesDel_noAF	Pathogenic	0.19
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.90	D;D;D
Eigen	Uncertain	0.32
Eigen_PC	Uncertain	0.41
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	0.98	.;D;.
M_CAP	Uncertain	0.24	D
MetaRNN	Uncertain	0.73	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Benign	1.7	L;L;L
PhyloP100		6.1
PrimateAI	Uncertain	0.76	T
PROVEAN	Uncertain	-3.0	.;D;D
REVEL	Pathogenic	0.69
Sift	Benign	0.17	.;T;T
Sift4G	Benign	0.16	T;T;T
Polyphen		0.82	P;P;P
Vest4		0.60
MVP		0.93
MPC		1.4
ClinPred		0.99	D
GERP RS		5.0
Varity_R		0.61
gMVP		0.93
Mutation Taster		=34/66	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.060		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: rs1555358380; hg19: chr14-55310784;