rs748132792

chr14-54844022-T-A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 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 (★). Synonymous variant affecting the same amino acid position (i.e. S250S) 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

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a chain GTP cyclohydrolase 1 (size 249) in uniprot entity GCH1_HUMAN there are 70 pathogenic changes around while only 7 benign (91%) in NM_000161.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GCH1	NM_000161.3	c.748A>T	p.Ser250Cys	missense_variant	6/6	ENST00000491895.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GCH1	ENST00000491895.7	c.748A>T	p.Ser250Cys	missense_variant	6/6	1	NM_000161.3	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000402 AC: 1 AN: 249008 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 134788

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 SAS 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

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

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

Uncertain significance, criteria provided, single submitter

clinical testing

Athena Diagnostics

Mar 08, 2017

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Computational scores

Source: dbNSFP v4.3

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;D;D
Eigen	Uncertain	0.35
Eigen_PC	Uncertain	0.37
FATHMM_MKL	Uncertain	0.92	D
M_CAP	Pathogenic	0.64	D
MetaRNN	Uncertain	0.49	T;T;T
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.9	M;M;M
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.61	T
Sift4G	Uncertain	0.0020	D;D;D
Polyphen		0.99	D;D;D
Vest4		0.11
MutPred		0.40		Loss of disorder (P = 0.013);Loss of disorder (P = 0.013);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

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

Publications

LitVar

Other links and lift over

dbSNP: rs748132792; hg19: chr14-55310740;