Genetic Variant PAH:c.169-2A>T (chr12-102894920-T-A) – ACMG Classification: Pathogenic (10 pts)

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1PM2

The NM_000277.3(PAH):c.169-2A>T variant causes a splice acceptor, intron change. The variant allele was found at a frequency of 0.000000687 in 1,456,302 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.9e-7 ( 0 hom. )

Consequence

PAH
NM_000277.3 splice_acceptor, intron

Scores

Splicing: ADA: 1.000

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 7.13

Publications

0 publications found

Variant links:

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]

PAH Gene-Disease associations (from GenCC):

phenylketonuria
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, Myriad Women’s Health, G2P
classic phenylketonuria
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
maternal phenylketonuria
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
mild hyperphenylalaninemia
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
mild phenylketonuria
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
tetrahydrobiopterin-responsive hyperphenylalaninemia/phenylketonuria
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

PAH links:

LOC124902999 (HGNC:):

LOC124902999 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 10 ACMG points.

PVS1

Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 4.5, offset of 35, new splice context is: ctgacccacattgaatctAGacc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.

PM2

Very rare variant in population databases, with high coverage;

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000277.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	PAH	NM_000277.3	MANE Select	c.169-2A>T		splice_acceptor intron	N/A	NP_000268.1	P00439
	PAH	NM_001354304.2		c.169-2A>T		splice_acceptor intron	N/A	NP_001341233.1	P00439

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	Effect	Exon Rank	Protein	UniProt
PAH	ENST00000553106.6	TSL:1 MANE Select	c.169-2A>T	splice_acceptor intron	N/A	ENSP00000448059.1	P00439
PAH	ENST00000549111.5	TSL:1	n.265-2A>T	splice_acceptor intron	N/A
PAH	ENST00000906695.1		c.169-2A>T	splice_acceptor intron	N/A	ENSP00000576754.1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.87e-7

AC:

AN:

1456302

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

724802

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33372

American (AMR)

AF:

0.00

AC:

AN:

44716

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26112

East Asian (EAS)

AF:

0.00

AC:

AN:

39652

South Asian (SAS)

AF:

0.00

AC:

AN:

86176

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52564

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5764

European-Non Finnish (NFE)

AF:

9.03e-7

AC:

AN:

1107730

Other (OTH)

AF:

0.00

AC:

AN:

60216

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.325

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.63

BayesDel_noAF

Pathogenic

0.28

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

0.93

FATHMM_MKL

Pathogenic

0.98

PhyloP100

7.1

GERP RS

6.2

Mutation Taster

=0/100

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.93

SpliceAI score (max)

1.0

Details are displayed if max score is > 0.2

DS_AL_spliceai

1.0

Position offset: -2

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over