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  • See Evidence submitted by expert panel for details.

Variant: NM_000277.2(PAH):c.2T>G (p.Met1Arg)

CA229509

102647 (ClinVar)

Gene: PAH
Condition: phenylketonuria
Inheritance Mode: Autosomal recessive inheritance
UUID: ba014c57-1ba6-4480-9f90-191b39ba497e
Approved on: 2019-07-07
Published on: 2019-07-07

HGVS expressions

NM_000277.2:c.2T>G
NM_000277.2(PAH):c.2T>G (p.Met1Arg)
NC_000012.12:g.102917129A>C
CM000674.2:g.102917129A>C
NC_000012.11:g.103310907A>C
CM000674.1:g.103310907A>C
NC_000012.10:g.101835037A>C
NG_008690.1:g.5474T>G
NG_008690.2:g.46282T>G
NM_000277.1:c.2T>G
NM_001354304.1:c.2T>G
NM_000277.3:c.2T>G
ENST00000307000.7:c.-146T>G
ENST00000546844.1:c.2T>G
ENST00000547319.1:n.313T>G
ENST00000549111.5:n.98T>G
ENST00000551337.5:c.2T>G
ENST00000551988.5:n.91T>G
ENST00000553106.5:c.2T>G
ENST00000635500.1:n.29-4231T>G
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Pathogenic

Met criteria codes 4
PVS1 PP4_Moderate PM2 PM3
Not Met criteria codes 2
PP3 PM5

Evidence Links 1

Expert Panel

Criteria Specification Information

Criteria Specifications for this VCEP
Evidence submitted by expert panel
Phenylketonuria VCEP
The PAH:p.M1R variant is a predicted start-lost variant in the canonical transcript of PAH (ENST00000553106). There are no known alternative start codons in other transcripts. The next in-frame Met is at amino acid 180 in exon 6. There are 49 pathogenic variants in ClinVar upstream of aa 180. The p.Met1Val variant has <3% enzyme activity as compared to wild type (PMID: 9450897), confirming start loss variants lead to loss of function of the PAH enzyme without re-initiation. The variant has been previously reported in 2 unrelated probands with classic PKU, in trans with the pathogenic variant p.R408W (PMID: 10679941; PM3); BH4 deficiency was excluded (PP4_Moderate). The variant is sufficiently rare in control databases (PM2). In summary, this variant meets criteria to be classified as pathogenic for PAH. PAH-specific ACMG/AMP criteria applied: PM3, PM2, PP4_moderate, PVS1.
Met criteria codes
PVS1
The PAH:p.M1R variant is a predicted start-lost variant in the canonical transcript of PAH (ENST00000553106). There are no known alternative start codons in other transcripts. The next in-frame Met is at amino acid 180 in exon 6. There are 49 pathogenic variants in ClinVar upstream of aa 180. The p.Met1Val variant has <3% enzyme activity as compared to wild type (PMID: 9450897), confirming start loss variants lead to loss of function of the PAH enzyme without re-initiation. Full strength applied per Steven Harrison.
PP4_Moderate
The variant has been previously reported in 2 unrelated probands with classic PKU, in trans with the known pathogenic p.R408W allele (PMID: 10679941). In both, BH4 deficiency was said to be excluded.

PM2
The variant is sufficiently rare in control databases including ethnically matched individuals, including gnomAD/ExAC, 1000 Genomes, and ESP (highest observed population frequency 0.0001, in the gnomAD African subpopulation), which is under the PAH-specific frequency cutoff of 0.0002 (PM2).
PM3
The variant has been previously reported in 2 unrelated probands with classic PKU, in trans with the known pathogenic p.R408W allele (PMID: 10679941).

Not Met criteria codes
PP3
No code specific comments provided, please refer to the summary above or general recommendations provided in the guideline
PM5
Loss of function start loss variant
Curation History
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