chr12-102852824-G-A

Variant names:

• chr12-102852824-G-A
• rs62507262
• NM_000277.3:c.833C>T

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PS3_Supporting PM2 PP4_Moderate PP3 PM3_Strong

This summary comes from the ClinGen Evidence Repository: The c.833C>T (p.Thr278Ile) variant in PAH has been reported in multiple individuals with PAH deficiency (BH4 deficiency ruled out), detected with pathogenic variants: R241C (PMID:21307867); R241C, A259T (2 patients), R413P, Y356X (PMID:15503242). Functional studies show a PAH enzyme activity of 1% compared to wild type (PMID:9860305). This variant is absent in population databases. Computational evidence supports a deleterious effect. In summary, this variant meets criteria to be classified as Pathogenic for PAH. PAH-specific ACMG/AMP criteria applied: PM3_strong, PP4_Moderate, PM2, PP3, PS3_supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA229803/MONDO:0009861/006

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: PAH NM_000277.3 missense
• Clinical Significance: Pathogenic reviewed by expert panel P:6 O:1
• Conservation: PhyloP100: 10.0

Genes affected

PAH (HGNC:8582): (phenylalanine hydroxylase) This gene encodes a member of the biopterin-dependent aromatic amino acid hydroxylase protein family. The encoded phenylalanine hydroxylase enzyme hydroxylates phenylalanine to tyrosine and is the rate-limiting step in phenylalanine catabolism. Deficiency of this enzyme activity results in the autosomal recessive disorder phenylketonuria. [provided by RefSeq, Aug 2017]

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PS3: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.
• PM3: For more information check the summary or visit ClinGen Evidence Repository.
• PP3: For more information check the summary or visit ClinGen Evidence Repository.
• PP4: For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PAH	NM_000277.3	c.833C>T	p.Thr278Ile	missense_variant	Exon 7 of 13	ENST00000553106.6	NP_000268.1
PAH	NM_001354304.2	c.833C>T	p.Thr278Ile	missense_variant	Exon 8 of 14		NP_001341233.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PAH	ENST00000553106.6	c.833C>T	p.Thr278Ile	missense_variant	Exon 7 of 13	1	NM_000277.3	ENSP00000448059.1
PAH	ENST00000307000.7	c.818C>T	p.Thr273Ile	missense_variant	Exon 8 of 14	5		ENSP00000303500.2
PAH	ENST00000549247.6	n.592C>T		non_coding_transcript_exon_variant	Exon 1 of 6	2
PAH	ENST00000635477.1	c.-8C>T		upstream_gene_variant		5		ENSP00000489230.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000410 AC: 6 AN: 1461770 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727188

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000151

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.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6 Other:1

Revision: reviewed by expert panel

Submissions by phenotype

Phenylketonuria Pathogenic:6

Jul 08, 2024

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: PAH c.833C>T (p.Thr278Ile) results in a non-conservative amino acid change located in the Aromatic amino acid hydroxylase, C-terminal domain (IPR019774) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251320 control chromosomes. c.833C>T has been reported in the literature in homozygous and compound heterozygous individuals affected with Phenylalanine Hydroxylase Deficiency (Phenylketonuria) (e.g. Lee_2004, Lee_2008). These data indicate that the variant is very likely to be associated with disease. A different variant affecting the same codon has been classified as pathogenic by our lab (c.833C>A, p.Thr278Asn), supporting the critical relevance of codon 278 to PAH protein function. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 18985011, 15503242). ClinVar contains an entry for this variant (Variation ID: 102863). Based on the evidence outlined above, the variant was classified as pathogenic. -

Feb 14, 2018

Counsyl

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 16, 2020

Natera, Inc.

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Mar 28, 2023

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 05, 2022

ClinGen PAH Variant Curation Expert Panel

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: curation

The c.833C>T (p.Thr278Ile) variant in PAH has been reported in multiple individuals with PAH deficiency (BH4 deficiency ruled out), detected with pathogenic variants: R241C (PMID: 21307867); R241C, A259T (2 patients), R413P, Y356X (PMID: 15503242). Functional studies show a PAH enzyme activity of 1% compared to wild type (PMID: 9860305). This variant is absent in population databases. Computational evidence supports a deleterious effect. In summary, this variant meets criteria to be classified as Pathogenic for PAH. PAH-specific ACMG/AMP criteria applied: PM3_strong, PP4_Moderate, PM2, PP3, PS3_supporting. -

Apr 07, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. Experimental studies have shown that this missense change affects PAH function (PMID: 9860305). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt PAH protein function. ClinVar contains an entry for this variant (Variation ID: 102863). This missense change has been observed in individual(s) with PAH-related conditions (PMID: 9860305, 15503242, 18985011, 23271928). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces threonine, which is neutral and polar, with isoleucine, which is neutral and non-polar, at codon 278 of the PAH protein (p.Thr278Ile). -

not provided Other:1

-

DeBelle Laboratory for Biochemical Genetics, MUHC/MCH RESEARCH INSTITUTE

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.98	D;D
Eigen	Pathogenic	0.79
Eigen_PC	Pathogenic	0.72
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.97	D;D
M_CAP	Pathogenic	0.59	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.6	M;.
PrimateAI	Pathogenic	0.80	T
PROVEAN	Pathogenic	-5.8	D;D
REVEL	Pathogenic	0.91
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0010	D;D
Polyphen		1.0	D;.
Vest4		0.97
MutPred		0.92		Loss of glycosylation at T278 (P = 0.0227);.;
MVP		0.99
MPC		0.25
ClinPred		1.0	D
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.89
gMVP		0.98

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs62507262; hg19: chr12-103246602;