rs1555358379

Variant names:

• chr14-54844017-T-G
• rs1555358379
• NM_000161.3:c.753A>C

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PM4

The NM_000161.3(GCH1):​c.753A>C​(p.Ter251Cysext*?) variant causes a stop lost change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: GCH1 NM_000161.3 stop_lost
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.83
• 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: Genomics England PanelApp, Orphanet, Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae)
• GTP cyclohydrolase I deficiency with hyperphenylalaninemia

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

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

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM4: Stoplost variant in NM_000161.3 Downstream stopcodon found after 11 codons.

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

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GCH1	NM_000161.3	MANE Select	c.753A>C	p.Ter251Cysext*?	stop_lost	Exon 6 of 6	NP_000152.1	P30793-1
	GCH1	NM_001024024.2		c.753A>C	p.Ter251Cysext*?	stop_lost	Exon 6 of 7	NP_001019195.1	P30793-1
	GCH1	NM_001424105.1		c.459A>C	p.Ter153Cysext*?	stop_lost	Exon 6 of 6	NP_001411034.1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GCH1	ENST00000491895.7	TSL:1 MANE Select	c.753A>C	p.Ter251Cysext*?	stop_lost	Exon 6 of 6	ENSP00000419045.2	P30793-1
	GCH1	ENST00000395514.5	TSL:1	c.753A>C	p.Ter251Cysext*?	stop_lost	Exon 6 of 7	ENSP00000378890.1	P30793-1
	GCH1	ENST00000543643.6	TSL:1	c.627-148A>C		intron	N/A	ENSP00000444011.2	P30793-4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
-	1	-	GTP cyclohydrolase I deficiency;C1851920:Dystonia 5 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Uncertain	0.038	T
BayesDel_noAF	Benign	-0.18
CADD	Benign	19
DANN	Benign	0.43
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	1.0	D
PhyloP100		7.8
Vest4		0.13
GERP RS		5.9
Mutation Taster		=9/191	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.27		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.27		Position offset: -12

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

Other links and lift over

dbSNP: rs1555358379; hg19: chr14-55310735;