NM_000161.3:c.344-1G>C

Variant names:

• chr14-54865437-C-G
• rs1555360050
• NM_000161.3:c.344-1G>C

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PVS1_Strong PM2 PP5_Moderate

The NM_000161.3(GCH1):​c.344-1G>C variant causes a splice acceptor, intron 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. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: GCH1 NM_000161.3 splice_acceptor, intron
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.76
• 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: Likely_pathogenic. The variant received 8 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.14608234 fraction of the gene. Cryptic splice site detected, with MaxEntScore 1.3, offset of 30, new splice context is: cgatgctatatttgatgaAGatc. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 14-54865437-C-G is Pathogenic according to our data. Variant chr14-54865437-C-G is described in ClinVar as Pathogenic. ClinVar VariationId is 465761.Status of the report is criteria_provided_single_submitter, 1 stars.

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.344-1G>C		splice_acceptor intron	N/A	NP_000152.1	P30793-1
	GCH1	NM_001024024.2		c.344-1G>C		splice_acceptor intron	N/A	NP_001019195.1	P30793-1
	GCH1	NM_001024070.2		c.344-1G>C		splice_acceptor intron	N/A	NP_001019241.1	P30793-4

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GCH1	ENST00000491895.7	TSL:1 MANE Select	c.344-1G>C		splice_acceptor intron	N/A	ENSP00000419045.2	P30793-1
	GCH1	ENST00000395514.5	TSL:1	c.344-1G>C		splice_acceptor intron	N/A	ENSP00000378890.1	P30793-1
	GCH1	ENST00000543643.6	TSL:1	c.344-1G>C		splice_acceptor intron	N/A	ENSP00000444011.2	P30793-4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 20

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions

Significance: Pathogenic

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	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.17
CADD	Pathogenic	31
DANN	Uncertain	0.99
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.88
FATHMM_MKL	Pathogenic	0.98	D
PhyloP100		7.8
GERP RS		5.4
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.92
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.32		Position offset: 16
DS_AL_spliceai		0.99		Position offset: -1

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

Other links and lift over

dbSNP: rs1555360050; hg19: chr14-55332155;