12-102894893-A-G

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PM5 PP3_Moderate PP5_Very_Strong

The NM_000277.3(PAH):c.194T>C(p.Ile65Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0006 in 1,613,738 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I65N) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: 𝑓 0.00030 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00063 (1 hom.)
• Consequence: PAH NM_000277.3 missense
• Clinical Significance: Pathogenic reviewed by expert panel P:25 O:2
• Conservation: PhyloP100: 8.30

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]

LOC124902999 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM1: In a hotspot region, there are 10 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 uncertain in NM_000277.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr12-102894893-A-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 102623.Status of the report is reviewed_by_expert_panel, 3 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.93
• PP5: Variant 12-102894893-A-G is Pathogenic according to our data. Variant chr12-102894893-A-G is described in ClinVar as [Pathogenic]. Clinvar id is 636.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr12-102894893-A-G is described in Lovd as [Pathogenic]. Variant chr12-102894893-A-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PAH	NM_000277.3	c.194T>C	p.Ile65Thr	missense_variant	3/13	ENST00000553106.6
LOC124902999	XR_007063428.1	n.863-9805A>G		intron_variant, non_coding_transcript_variant
PAH	NM_001354304.2	c.194T>C	p.Ile65Thr	missense_variant	4/14
PAH	XM_017019370.2	c.194T>C	p.Ile65Thr	missense_variant	3/7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PAH	ENST00000553106.6	c.194T>C	p.Ile65Thr	missense_variant	3/13	1	NM_000277.3	P1

Frequencies

GnomAD3 genomes AF: 0.000296 AC: 45 AN: 152226 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.000169

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000131

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000529

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000271 AC: 68 AN: 251202 Hom.: 0 AF XY: 0.000265 AC XY: 36 AN XY: 135772

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.0000867

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000537

Gnomad OTH exome AF: 0.000326

GnomAD4 exome AF: 0.000632 AC: 924 AN: 1461512 Hom.: 1 Cov.: 30 AF XY: 0.000633 AC XY: 460 AN XY: 727086

Gnomad4 AFR exome AF: 0.000119

Gnomad4 AMR exome AF: 0.0000894

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000348

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.000789

Gnomad4 OTH exome AF: 0.000596

GnomAD4 genome AF: 0.000296 AC: 45 AN: 152226 Hom.: 0 Cov.: 32 AF XY: 0.000309 AC XY: 23 AN XY: 74362

Gnomad4 AFR AF: 0.000169

Gnomad4 AMR AF: 0.000131

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000529

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000507 Hom.: 0

Bravo AF: 0.000302

TwinsUK AF: 0.00108 AC: 4

ALSPAC AF: 0.00 AC: 0

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000581 AC: 5

ExAC AF: 0.000181 AC: 22

Asia WGS AF: 0.000289 AC: 1 AN: 3478

EpiCase AF: 0.000436

EpiControl AF: 0.000474

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:25 Other:2

Revision: reviewed by expert panel

Submissions by phenotype

Phenylketonuria Pathogenic:14 Other:1

Pathogenic, criteria provided, single submitter	research	UNC Molecular Genetics Laboratory, University of North Carolina at Chapel Hill	-	The PAH c.194T>C (p.I65T) missense variant has been found in the homozygous and compound heterozygous state in individuals with a range of clinical phenotypes including hyperphenylalaninemia; mild phenylketonuria, and classic phenylketonuria (PMID: 9254847; 1301201; 10767174; 12501224). -
Pathogenic, no assertion criteria provided	literature only	OMIM	Jan 01, 1992	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 31, 2024	This sequence change replaces isoleucine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 65 of the PAH protein (p.Ile65Thr). This variant is present in population databases (rs75193786, gnomAD 0.05%). This missense change has been observed in individual(s) with PAH-related conditions (PMID: 12655546, 23500595, 25596310). ClinVar contains an entry for this variant (Variation ID: 636). 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 with a positive predictive value of 80%. Experimental studies have shown that this missense change affects PAH function (PMID: 12655546, 17935162, 26803807). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Apr 28, 2022	- -
Pathogenic, reviewed by expert panel	curation	ClinGen PAH Variant Curation Expert Panel	Apr 21, 2018	PAH-specific ACMG/AMP criteria applied: PM3_VeryStrong: Detected with Y414C (P), R408W (P), P281L (P), IVS10nt-11 (P), R252W (P/LP), and R243Q(P). (PMID:12501224; PMID:1301201; PMID:10767174); PP3: Predicted dleterious in SIZFT, Polyphen2, MutationTaster. REVEL=0.985; PP4_Moderate: Detected in a patient with mild PKU. BH4 deficiency excluded. Upgraded per ClinGen PAH EP. (PMID:12501224); PS3: 25% mutant enzyme activity in COS cells as compared in wt (PMID:1301201). In summary this variant meets criteria to be classified as pathogenic for phenylketonuria in an autosomal recessive manner based on the ACMG/AMP criteria applied as specified by the PAH Expert Panel: (PM3_VeryStrong, PP3, PP4_Moderate, PS3). -
Pathogenic, criteria provided, single submitter	clinical testing	3billion	Jan 03, 2022	Functional studies provide strong evidence of the variant having a damaging effect on the gene or gene product (PMID: 1301201, PS3_S). In silico tool predictions suggest damaging effect of the variant on gene or gene product (REVEL: 0.985, 3CNET: 0.998, PP3_P). A missense variant is a common mechanism associated with Phenylketonuria; PKU (PP2_P). It is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: 0.000294, PM2_M). The same variant was previously reported several times in trans with another pathogenic variant in this gene (PMID: 1301201, 10767174, 12501224) (PM3_VS). A different missense change at the same codon has been reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000102622,VCV000102623, PMID:22526846,9521426,12501224, PM5_M). Therefore, this variant is classified as pathogenic according to the recommendation of ACMG/AMP guideline. -
Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -
Pathogenic, no assertion criteria provided	research	Division of Human Genetics, Children's Hospital of Philadelphia	Jul 19, 2016	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Jun 29, 2022	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Dec 24, 2019	NM_000277.1(PAH):c.194T>C(I65T) is classified as likely pathogenic in the context of phenylalanine hydroxylase deficiency and may be associated with classic, variant, or non-PKU hyperphenylalaninemia. Sources cited for classification include the following: PMID 11524738, 23500595, 11326337, 1301187, 17935162, 15557004, 8533759, and 9781015. Classification of NM_000277.1(PAH):c.194T>C(I65T) is based on the following criteria: This variant has been observed more frequently in patients with clinical diagnoses than in healthy populations. Please note: this variant was assessed in the context of healthy population screening. -
Pathogenic, criteria provided, single submitter	clinical testing	Greenwood Genetic Center Diagnostic Laboratories, Greenwood Genetic Center	Jul 26, 2022	PS3, PM3_Very Strong, PP3 -
Pathogenic, criteria provided, single submitter	clinical testing	Victorian Clinical Genetics Services, Murdoch Childrens Research Institute	Jun 24, 2022	Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as pathogenic. The following criteria are met: 0102 - Loss of function is a known mechanism of disease in this gene and is associated with phenylketonuria (MIM#261600). (I) 0106 - This gene is associated with autosomal recessive disease. (I) 0200 - Variant is predicted to result in a missense amino acid change from isoleucine to threonine. (I) 0251 - This variant is heterozygous. (I) 0304 - Variant is present in gnomAD (v2) <0.01 for a recessive condition (83 heterozygotes, 0 homozygotes). (SP) 0309 - An alternative amino acid change at the same position has been observed in gnomAD (v2) (2 heterozygotes, 0 homozygotes). (I) 0501 - Missense variant consistently predicted to be damaging by multiple in silico tools or highly conserved with a major amino acid change. (SP) 0600 - Variant is located in the annotated ACT domain (DECIPHER). (I) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant is a well-reported pathogenic variant (ClinVar). It is one of the most common pathogenic variants reported in individuals with phenylketonuria (PMID: 33465300) and is associated with classic PKU (BIOPKU database). (SP) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jan 26, 2017	Variant summary: The PAH c.194T>C (p.Ile65Thr) variant located in the ACT domain (via InterPro) involves the alteration of a conserved nucleotide, which 5/5 in silico tools predict a damaging outcome. The variant of interest was observed in the large, broad control population, ExAC, with an allele frequency of 22/121240 (1/5509), which does not exceed the estimated maximal expected allele frequency for a pathogenic PAH variant of 1/126. Multiple publications cite the variant in affected individuals, predominantly as compound heterozygous and was indicated to cause a mild PKU phenotype. In addition, multiple clinical diagnostic laboratories and databases cite the variant as "pathogenic." Therefore, the variant of interest has been classified as "Pathogenic." -
not provided, no classification provided	literature only	GeneReviews	-	- -

not provided Pathogenic:8 Other:1

not provided, no classification provided	literature only	DeBelle Laboratory for Biochemical Genetics, MUHC/MCH RESEARCH INSTITUTE	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Apr 27, 2021	The PAH c.194T>C (p.Ile65Thr) variant is associated with a variable phenotype that ranges from non-PKU hyperphenylalaninemia to classic PKU (PMID: 1301201 (1992), 12501224 (2002), 15557004 (2004)). Assessment of experimental evidence regarding the effect of this variant suggests it causes decreased enzyme activity with a residual activity of about 30% (PMID: 26803807 (2016), 12655546 (2003), 1301201 (1992)). Therefore, the variant is classified as pathogenic. -
Pathogenic, no assertion criteria provided	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Sep 22, 2020	Common pathogenic PAH variant most often reported in association with mild-moderate phenylketonuria (PKU) (Pey et al., 2007; Zurfluh et al, 2008; Danecka et al. 2015). It has also been identified in an individual with classic PKU (Couce et al., 2013).; Functional studies demonstrate I65T is associated with reduced phenylalanine hydroxylase activity compared to wild-type (Danecka et al., 2015); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 1301187, 17924342, 1301201, 22975760, 30963030, 23500595, 17935162, 11326337, 23559577, 12655546, 25596310, 19036622, 11461190, 21953985, 27121329, 28645531, 25087612, 27264808, 26803807, 19194782, 29030855, 30648773, 30747360, 31980526, 30275481, 31589614, 32668217, 32853555) -
Pathogenic, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Jul 01, 2023	PAH: PM3:Very Strong, PM2, PP3, PS3:Supporting -
Pathogenic, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Oct 08, 2021	PP3, PP4_moderate, PM2, PM3_strong -
Pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Jul 02, 2018	- -
Likely pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -

PAH-related disorder Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Aug 11, 2023

The PAH c.194T>C variant is predicted to result in the amino acid substitution p.Ile65Thr. This variant has been reported in the literature as causative for phenylalanine hydroxylase deficiency (for example, see Eisensmith and Woo et al. 1992. PubMed ID: 1301187; Zschocke et al. 1995. PubMed ID: 8533759; Jeannesson-Thivisol et al. 2015. PubMed ID: 26666653; Vela-Amieva et al. 2021. PubMed ID: 34828281). Based on functional studies, the p.Ile65Thr amino acid change has been reported to result in reduced PAH protein level and reduced enzyme activity, and has been classified as a BH4-responsive amino acid substitution (Zurflüh et al. 2008. PubMed ID: 17935162; Shi et al. 2012. PubMed ID: 21953985). Multiple other laboratories, as well as the ClinGen PAH Variant Curation Expert Panel, classify this variant as pathogenic or likely pathogenic (https://www.ncbi.nlm.nih.gov/clinvar/variation/636/). Based on these observations, this variant is interpreted as pathogenic. -

Inborn genetic diseases Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 26, 2021

The c.194T>C (p.I65T) alteration is located in coding exon 3 of the PAH gene. This alteration results from a T to C substitution at nucleotide position 194, causing the isoleucine (I) at amino acid position 65 to be replaced by a threonine (T). Based on data from the Genome Aggregation Database (gnomAD), the PAH c.194T>C alteration was observed in 0.03% (83/282610) of total alleles studied, with a frequency of 0.06% (72/129008) in the European (non-Finnish) subpopulation. No homozygotes were observed. The c.194T>C (p.I65T) alteration has been described homozygous and compound heterozygous with a second allele in multiple unrelated families with phenotypes ranging from hyperphenylalaninemia to classic PKU (Couce, 2013; Desviat, 2004; John, 1992; Muntau, 2002; Rivera, 2000). The p.I65 amino acid is conserved in available vertebrate species. In vitro functional studies determined protein expressing the c.194T>C (p.I65T) alteration decreased PAH activity to less than 50% of wild type activity. When observed with a second deleterious alteration, residual PAH activity ranged between 5.5% to 48% (John, 1992; Shen, 2016). The p.I65T alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, this alteration is classified as pathogenic. -

See cases Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Laboratorio de Genetica e Diagnostico Molecular, Hospital Israelita Albert Einstein

Mar 08, 2019

ACMG classification criteria: PS3, PS4, PM1, PM2, PM3, PP3 -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.59
Cadd	Pathogenic	28
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D;D;D;D
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D;D;D;D
M_CAP	Pathogenic	0.87	D
MetaRNN	Pathogenic	0.93	D;D;D;D
MetaSVM	Pathogenic	0.98	D
MutationAssessor	Pathogenic	4.3	H;.;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.76	T
PROVEAN	Pathogenic	-4.5	D;D;D;D
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	D;D;D;D
Sift4G	Pathogenic	0.0010	D;D;D;.
Polyphen		1.0	D;.;.;.
Vest4		0.95
MVP		0.98
MPC		0.26
ClinPred		0.94	D
GERP RS		6.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.99
gMVP		0.92

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: rs75193786; hg19: chr12-103288671;