12-102840394-A-T

Position:

• chr12-102840394-A-T

Variant summary

Our verdict is Pathogenic. Variant got 6 ACMG points: 6P and 0B. PM3 PM2 PP4_Moderate

This summary comes from the ClinGen Evidence Repository: This c.1315+6T>A (IVS12+6T>A) variant was documented three times in Southern Chinese patients and 5 times in Northern Chinese patients with PAH deficiency; DHPR activity, biopterin and/or pteridine analysis was performed to rule out other causes of hyperphenylalaninemia (PMID:26503515). This variant was documented in at least 7 patients with PAH deficiency, with a pathogenic PAH variant in trans (PMID:16256386, 23932990, 28982351). This variant is absent from the population databases ExAC and gnomAD. In summary, this variant meets criteria to be classified as pathogenic for PAH. PAH-specific ACMG/AMP criteria applied: PM2, PP4_moderate, PM3_very strong. LINK:https://erepo.genome.network/evrepo/ui/classification/CA229431/MONDO:0009861/006

• Frequency: Genomes: not found (cov: 32)
• Consequence: PAH NM_000277.3 splice_donor_region, intron
• Scores: Splicing: ADA: 0.9295
• Clinical Significance: Pathogenic reviewed by expert panel P:6 O:1
• Conservation: PhyloP100: 0.743

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 6 ACMG points.

• 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/exons	MANE	Protein	UniProt
PAH	NM_000277.3	c.1315+6T>A		splice_donor_region_variant, intron_variant		ENST00000553106.6	NP_000268.1
PAH	NM_001354304.2	c.1315+6T>A		splice_donor_region_variant, intron_variant			NP_001341233.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
PAH	ENST00000553106.6	c.1315+6T>A		splice_donor_region_variant, intron_variant		1	NM_000277.3	ENSP00000448059	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 26

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000756

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6 Other:1

Revision: reviewed by expert panel

Submissions by phenotype

Phenylketonuria Pathogenic:5

Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Feb 28, 2024	- -
Pathogenic, reviewed by expert panel	curation	ClinGen PAH Variant Curation Expert Panel	Nov 05, 2019	This c.1315+6T>A (IVS12+6T>A) variant was documented three times in Southern Chinese patients and 5 times in Northern Chinese patients with PAH deficiency; DHPR activity, biopterin and/or pteridine analysis was performed to rule out other causes of hyperphenylalaninemia (PMID: 26503515). This variant was documented in at least 7 patients with PAH deficiency, with a pathogenic PAH variant in trans (PMID: 16256386, 23932990, 28982351). This variant is absent from the population databases ExAC and gnomAD. In summary, this variant meets criteria to be classified as pathogenic for PAH. PAH-specific ACMG/AMP criteria applied: PM2, PP4_moderate, PM3_very strong. -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jun 09, 2023	Variant summary: PAH c.1315+6T>A alters a conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Several computational tools predict a significant impact on normal splicing: Three predict the variant weakens the canonical 5' splice donor site. However, these predictions have yet to be confirmed by functional studies. The variant was absent in 251404 control chromosomes. c.1315+6T>A has been reported in the literature in multiple individuals affected with Phenylalanine Hydroxylase Deficiency (Phenylketonuria) such as mild hyperphenylalaninaemia (MHP) or mild Phenyketonuria (mPKU) (example, Li_2018, Hillert_2020). These data indicate that the variant is very likely to be associated with disease. 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: 32668217, 30050108). Two clinical diagnostic laboratories and the ClinGen PAH Variant Curation Expert Panel have submitted clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as pathogenic/likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Aug 02, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Mar 10, 2020	For these reasons, this variant has been classified as Pathogenic. Nucleotide substitutions within the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies. This variant has been observed in several individuals affected with mild phenylketonuria or mild hyperphenylalaninemia (PMID: 16256386, 29731766, 23932990). This variant is also known as IVS12+6T>A in the literature. ClinVar contains an entry for this variant (Variation ID: 102590). This variant is not present in population databases (ExAC no frequency). This sequence change falls in intron 12 of the PAH gene. It does not directly change the encoded amino acid sequence of the PAH protein, but it affects a nucleotide within the consensus splice site of the intron. -

PAH-related disorder Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

Aug 06, 2024

The PAH c.1315+6T>A variant is predicted to interfere with splicing. This variant is also referred to as IVS12+6T>A in the literature. This variant has been reported with a second PAH variant in individuals with mild phenylketonuria or hyperphenylalaninemia (see, for example, Song et al. 2005. PubMed ID: 16256386; Table S2, Li et al. 2018. PubMed ID: 30050108; Supplementary Table 2, Zeng et al. 2023. PubMed ID: 36845377). This variant is predicted to alter splicing based on available splicing prediction programs (SpliceAI, Jaganathan et al. 2019. PubMed ID: 30661751). However, the use of computer prediction programs is not equivalent to functional evidence. This variant has not been reported in a large population database, indicating this variant is rare. This variant is interpreted as pathogenic or likely pathogenic in ClinVar, including by the ClinGen PAH Variant Curation Expert Panel (https://www.ncbi.nlm.nih.gov/clinvar/variation/102590/). This variant is interpreted as pathogenic. -

not provided Other:1

not provided, no classification provided

literature only

DeBelle Laboratory for Biochemical Genetics, MUHC/MCH RESEARCH INSTITUTE

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.35
CADD	Benign	14
DANN	Benign	0.92
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.93
dbscSNV1_RF	Benign	0.56
SpliceAI score (max)		0.49		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.49		Position offset: 6

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

Publications

LitVar

Other links and lift over

dbSNP: rs62508650; hg19: chr12-103234172;