12-102894788-T-C
Variant summary
Our verdict is Uncertain significance. The variant received 2 ACMG points: 3P and 1B. PP4BP4PM3
This summary comes from the ClinGen Evidence Repository: PAH-specific ACMG/AMP criteria applied: BP4: In silico overwhelmingly predict benign. REVEL = 0.553; PP4: Detected in a patient with non PKU hyperphe (PMID:11244681); PM3: H100R detected with IVS10 (PMID:11244681). In summary this variant meets criteria to be classified as uncertain significance for phenylketonuria in an autosomal recessive manner based on the ACMG/AMP criteria applied as specified by the PAH Expert Panel: (BP4, PP4, PM3). LINK:https://erepo.genome.network/evrepo/ui/classification/CA6748985/MONDO:0009861/006
Frequency
Consequence
NM_000277.3 missense
Scores
Clinical Significance
Conservation
Publications
- phenylketonuriaInheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, ClinGen, Myriad Women’s Health
- classic phenylketonuriaInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- maternal phenylketonuriaInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- mild hyperphenylalaninemiaInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- mild phenylketonuriaInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- tetrahydrobiopterin-responsive hyperphenylalaninemia/phenylketonuriaInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
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ACMG classification
Our verdict: Uncertain_significance. The variant received 2 ACMG points.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
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PAH | NM_000277.3 | c.299A>G | p.His100Arg | missense_variant | Exon 3 of 13 | ENST00000553106.6 | NP_000268.1 | |
PAH | NM_001354304.2 | c.299A>G | p.His100Arg | missense_variant | Exon 4 of 14 | NP_001341233.1 | ||
PAH | XM_017019370.2 | c.299A>G | p.His100Arg | missense_variant | Exon 3 of 7 | XP_016874859.1 | ||
LOC124902999 | XR_007063428.1 | n.863-9910T>C | intron_variant | Intron 2 of 2 |
Ensembl
Frequencies
GnomAD3 genomes AF: 0.000342 AC: 52AN: 152230Hom.: 0 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.000314 AC: 79AN: 251456 AF XY: 0.000361 show subpopulations
GnomAD4 exome AF: 0.000594 AC: 869AN: 1461836Hom.: 1 Cov.: 31 AF XY: 0.000589 AC XY: 428AN XY: 727224 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.000342 AC: 52AN: 152230Hom.: 0 Cov.: 32 AF XY: 0.000255 AC XY: 19AN XY: 74378 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
Phenylketonuria Uncertain:7
The PAH c.299A>G (p.His100Arg) variant was identified in ClinVar (classified as a VUS by multiple sources) and dbSNP (rs148393887). The PAH c.299A>G (p.His100Arg) missense variant has been reported in one individual in a compound heterozygous state with a known pathogenic intronic variant (Mallolas et al. 1999). The individual was described as having non-phenylketonuria hyperphenylalaninemia, which is included in the PAH deficiency spectrum. The variant was identified in control databases in 83 of 282, 858 chromosomes (0 homozygous) at a frequency of 0.0293%, and was observed at the highest frequency in the European Non-Finnish population in 129,164 of 282, 858 chromosomes (freq: 0.0503%) (Genome Aggregation Database March 6, 2019, v2.1.1). The p. His100Arg residue is conserved in mammals and computational analyses (MUT Assesor, PolyPhen-2, SIFT, MutationTaster, Revel, FATHMM, MetaLR, DANN) provide inconsistent predictions regarding the impact to the protein; this information is not very predictive of pathogenicity. The variant occurs outside of the splicing consensus sequence and in silico or computational prediction software programs (Splice AI exome) do not predict a deleterious effect on splicing. In summary, based on the above information the clinical significance of this variant cannot be determined with certainty at this time. This variant is classified as a variant of uncertain significance.PAH is associated with autosomal recessive Phenylketonuria (PKU) and non-PKU mild hyperphenylalaninemia (Phenotype MIM number: 261600). PKU is an inborn error of metabolism resulting from a deficiency of phenylalanine hydroxylase (PAH), an enzyme that catalyzes the hydroxylation of phenylalanine to tyrosine, the rate-limiting step in phenylalanine catabolism. If undiagnosed and untreated, phenylketonuria can result in impaired postnatal cognitive development resulting from a neurotoxic effect of hyperphenylalaninemia (Zurfluh et al., 2008). -
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This sequence change replaces histidine, which is basic and polar, with arginine, which is basic and polar, at codon 100 of the PAH protein (p.His100Arg). This variant is present in population databases (rs148393887, gnomAD 0.05%). This missense change has been observed in individual(s) with hyperphenylalaninemia (PMID: 11244681). ClinVar contains an entry for this variant (Variation ID: 306914). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -
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PAH-specific ACMG/AMP criteria applied: BP4: In silico overwhelmingly predict benign. REVEL = 0.553; PP4: Detected in a patient with non PKU hyperphe (PMID:11244681); PM3: H100R detected with IVS10 (PMID:11244681). In summary this variant meets criteria to be classified as uncertain significance for phenylketonuria in an autosomal recessive manner based on the ACMG/AMP criteria applied as specified by the PAH Expert Panel: (BP4, PP4, PM3). -
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. -
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not specified Uncertain:1
Variant summary: PAH c.299A>G (p.His100Arg) results in a non-conservative amino acid change located in the ACT domain (IPR002912) of the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.00031 in 251456 control chromosomes (gnomAD). This frequency is not significantly higher than expected for a pathogenic variant in PAH causing Phenylalanine Hydroxylase Deficiency (Phenylketonuria) (0.00031 vs 0.0079), allowing no conclusion about variant significance. c.299A>G has been reported in the literature in at least an individual affected with non PKU HPA (Mallolas_1999). This report however, does not provide unequivocal conclusions about association of the variant with Phenylalanine Hydroxylase Deficiency (Phenylketonuria). To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Five ClinVar submitters (evaluation after 2014) including an expert panel (ClinGen PAH Variant Curation Expert Panel) cite the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -
Inborn genetic diseases Uncertain:1
The c.299A>G (p.H100R) alteration is located in exon 3 (coding exon 3) of the PAH gene. This alteration results from a A to G substitution at nucleotide position 299, causing the histidine (H) at amino acid position 100 to be replaced by an arginine (R). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -
not provided Uncertain:1
In silico analysis supports that this missense variant does not alter protein structure/function; This variant is associated with the following publications: (PMID: 25087612, 30311390, 11244681, 32668217, 10598814) -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at