The NM_000277.3(PAH):c.1183G>C variant is PAH is a missense variant predicted to cause substitution of alanine by proline at amino acid 395 (p.Ala395Pro). At least one patient with this variant displayed plasma phenylalanine concentration persistently above 120umol/L (2mg/dL) AND sequencing of genes in the BH4 cofactor metabolism pathway excluded a defect of BH4 cofactor metabolism, which is highly specific for PAH deficiency (PP4_Moderate, PMIDs: 9634518, 12836060). This variant has been detected in at least 5 individuals with Phenylketonuria. All individuals were compound heterozygous for the variant and distinct pathogenic variants in unknown phase (PM3_strong, PMIDs: 17502162, 12836060, 11999982, 7726156). The highest population minor allele frequency in gnomAD v4.1.0 is 0.00001017 in European (non-Finnish), which is lower than the ClinGen PAH Variant Curation Expert Panel threshold (<0.0002) for PM2_Supporting, meeting this criterion (PM2_Supporting). Mutant PAH enzyme activity showed 14-17% enzyme activity in vitro with < 10 benign/pathogenic variant controls, indicating that this variant impacts protein function (PS3_supporting, PMID: 11161839). The computational predictor REVEL gives a score of 0.988, which meets the threshold of 0.932, evidence that correlates with strong impact to PAH function (PP3_Strong). In summary, this variant meets criteria to be classified as pathogenic for PAH. PAH-specific ACMG/AMP criteria applied: PP4_moderate, PM3_strong, PM2_supporting, PS3_supporting, PP3_strong. Version 2.0, 7/16/2024.