NM_000277.3:c.977G>A

Variant names:

• chr12-102844424-C-T
• rs62514959
• NM_000277.3:c.977G>A

Variant summary

Our verdict is Pathogenic. The variant received 14 ACMG points: 14P and 0B. PM3 PM2 PP4_Moderate PVS1

This summary comes from the ClinGen Evidence Repository: The c.977G>A (p.Trp326Ter) is a variant in PAH is a null variant (nonsense variant) in a gene where LOF is a known mechanism of disease, leading to premature truncation and NMD (PVS1). It is present at extremely low frequencies in ethnically diverse control databases (gnomAD AF 0.00000399; PAH PM2 cutoff: <0.0002) (PM2). It has been identified in at least five PKU cases in whom BH4 deficiency was excluded (PP4_Moderate), in four cases in trans with known pathogenic variants (PM3_VeryStrong). It has been identified in at least two Chinese classic PKU cases (PMID:261600; PMID:1301927; PMID:28982351), in trans with the known pathogenic (per PAH VCEP) p.Y356X and p.R243Q variants; as a single heterozygous variant in a Chinese classic PKU case with BH4 deficiency excluded (PMID:24705691); in trans with the known pathogenic (per PAH VCEP) p.R261Q variant in one Slovak case with classic PKU with BH4 deficiency said to be excluded (PMID:23764561); one Chinese proband with mild hyperphenylalanemia in trans with c.1197A>T (p.V399V) (PMID:25456745). It is also listed Pathogenic in ClinVar by three labs (variant ID 579). Classification: PathogenicSupporting Criteria: PVS1, PM2; PM3_VeryStrong; PP4_Moderate LINK:https://erepo.genome.network/evrepo/ui/classification/CA229887/MONDO:0009861/006

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: PAH NM_000277.3 stop_gained
• Clinical Significance: Pathogenic reviewed by expert panel P:5 O:1
• Conservation: PhyloP100: 6.06
• Publications: 12 publications found

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]

PAH Gene-Disease associations (from GenCC):

• phenylketonuria

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, ClinGen, Myriad Women’s Health
• classic phenylketonuria

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• maternal phenylketonuria

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• mild hyperphenylalaninemia

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• mild phenylketonuria

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• tetrahydrobiopterin-responsive hyperphenylalaninemia/phenylketonuria

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 14 ACMG points.

• PVS1: 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.
• 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.977G>A	p.Trp326*	stop_gained	Exon 10 of 13	ENST00000553106.6	NP_000268.1
PAH	NM_001354304.2	c.977G>A	p.Trp326*	stop_gained	Exon 11 of 14		NP_001341233.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PAH	ENST00000553106.6	c.977G>A	p.Trp326*	stop_gained	Exon 10 of 13	1	NM_000277.3	ENSP00000448059.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000399 AC: 1 AN: 250724 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1458902 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 725976

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33414

American (AMR) AF: 0.00 AC: 0 AN: 44664

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26094

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39690

South Asian (SAS) AF: 0.00 AC: 0 AN: 86150

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53382

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 9.01e-7 AC: 1 AN: 1109468

Other (OTH) AF: 0.00 AC: 0 AN: 60278

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.006664), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:5 Other:1

Revision: reviewed by expert panel

Submissions by phenotype

Phenylketonuria Pathogenic:5

Nov 22, 2023

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Apr 13, 2020

ClinGen PAH Variant Curation Expert Panel

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: curation

The c.977G>A (p.Trp326Ter) is a variant in PAH is a null variant (nonsense variant) in a gene where LOF is a known mechanism of disease, leading to premature truncation and NMD (PVS1). It is present at extremely low frequencies in ethnically diverse control databases (gnomAD AF 0.00000399; PAH PM2 cutoff: <0.0002) (PM2). It has been identified in at least five PKU cases in whom BH4 deficiency was excluded (PP4_Moderate), in four cases in trans with known pathogenic variants (PM3_VeryStrong). It has been identified in at least two Chinese classic PKU cases (PMID: 261600; PMID: 1301927; PMID: 28982351), in trans with the known pathogenic (per PAH VCEP) p.Y356X and p.R243Q variants; as a single heterozygous variant in a Chinese classic PKU case with BH4 deficiency excluded (PMID: 24705691); in trans with the known pathogenic (per PAH VCEP) p.R261Q variant in one Slovak case with classic PKU with BH4 deficiency said to be excluded (PMID: 23764561); one Chinese proband with mild hyperphenylalanemia in trans with c.1197A>T (p.V399V) (PMID: 25456745). It is also listed Pathogenic in ClinVar by three labs (variant ID 579). Classification: Pathogenic Supporting Criteria: PVS1, PM2; PM3_VeryStrong; PP4_Moderate -

Nov 01, 1989

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Mar 29, 2021

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. This variant has been observed in individual(s) with hyperphenylalaninemia (PMID: 29499199). ClinVar contains an entry for this variant (Variation ID: 579). This sequence change creates a premature translational stop signal (p.Trp326*) in the PAH gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in PAH are known to be pathogenic (PMID: 1301187, 9634518). This variant is not present in population databases (ExAC no frequency). -

Apr 20, 2018

Counsyl

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

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
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.66
CADD	Pathogenic	48
DANN	Uncertain	1.0
Eigen	Pathogenic	0.95
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.98	D
PhyloP100		6.1
Vest4		0.95
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Mutation Taster		=0/200	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.24		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.24		Position offset: 7

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

Other links and lift over

dbSNP: rs62514959; hg19: chr12-103238202;