chr14-54844022-T-A

Variant names:

• chr14-54844022-T-A
• rs748132792
• NM_000161.3:c.748A>T

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM2 PP2 PP3_Moderate

The NM_000161.3(GCH1):​c.748A>T​(p.Ser250Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,828 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. S250G) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: GCH1 NM_000161.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.30
• 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.

• 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.
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000161.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GCH1	NM_000161.3	MANE Select	c.748A>T	p.Ser250Cys	missense	Exon 6 of 6	NP_000152.1
	GCH1	NM_001024024.2		c.748A>T	p.Ser250Cys	missense	Exon 6 of 7	NP_001019195.1
	GCH1	NM_001424105.1		c.454A>T	p.Ser152Cys	missense	Exon 6 of 6	NP_001411034.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GCH1	ENST00000491895.7	TSL:1 MANE Select	c.748A>T	p.Ser250Cys	missense	Exon 6 of 6	ENSP00000419045.2
	GCH1	ENST00000395514.5	TSL:1	c.748A>T	p.Ser250Cys	missense	Exon 6 of 7	ENSP00000378890.1
	GCH1	ENST00000254299.8	TSL:1	n.896A>T		non_coding_transcript_exon	Exon 6 of 6

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00000402 AC: 1 AN: 249008 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461828 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727228

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.0000224 AC: 1 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111950

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

TwinsUK AF: 0.00 AC: 0

ALSPAC AF: 0.000259 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Mar 08, 2017

Athena Diagnostics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.39
BayesDel_addAF	Uncertain	0.16	D
BayesDel_noAF	Uncertain	0.070
CADD	Pathogenic	33
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.75	D
Eigen	Uncertain	0.35
Eigen_PC	Uncertain	0.37
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Uncertain	0.93	D
M_CAP	Pathogenic	0.64	D
MetaRNN	Uncertain	0.49	T
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.9	M
PhyloP100		3.3
PrimateAI	Uncertain	0.61	T
PROVEAN	Uncertain	-3.1	D
REVEL	Pathogenic	0.65
Sift	Uncertain	0.0020	D
Sift4G	Uncertain	0.0020	D
Polyphen		0.99	D
Vest4		0.11
MutPred		0.40		Loss of disorder (P = 0.013)
MVP		0.72
MPC		1.8
ClinPred		0.96	D
GERP RS		4.8
Varity_R		0.65
gMVP		0.92
Mutation Taster		=54/46	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.93		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.93		Position offset: 2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs748132792; hg19: chr14-55310740;