Genetic Variant PPP1CB:c.521-8A>T (chr2-28783899-A-T) – ACMG Classification: Likely_benign (-2 pts)

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2BP4_Strong

The NM_002709.3(PPP1CB):c.521-8A>T variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000688 in 1,452,946 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on 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

PPP1CB
NM_002709.3 splice_region, intron

Scores

Splicing: ADA: 0.001159

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 0.0430

Variant links:

Genes affected

PPP1CB (HGNC:9282): (protein phosphatase 1 catalytic subunit beta) The protein encoded by this gene is one of the three catalytic subunits of protein phosphatase 1 (PP1). PP1 is a serine/threonine specific protein phosphatase known to be involved in the regulation of a variety of cellular processes, such as cell division, glycogen metabolism, muscle contractility, protein synthesis, and HIV-1 viral transcription. Mouse studies suggest that PP1 functions as a suppressor of learning and memory. Two alternatively spliced transcript variants encoding distinct isoforms have been observed. [provided by RefSeq, Jul 2008]

PPP1CB links:

SPDYA (HGNC:30613): (speedy/RINGO cell cycle regulator family member A) Enables protein kinase activator activity and protein kinase binding activity. Involved in several processes, including G1/S transition of mitotic cell cycle; positive regulation of cell population proliferation; and positive regulation of protein kinase activity. Located in nucleoplasm. [provided by Alliance of Genome Resources, Apr 2022]

SPDYA links:

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ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.69).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PPP1CB	NM_002709.3 link	c.521-8A>T		splice_region_variant, intron_variant	Intron 4 of 7	ENST00000395366.3	NP_002700.1	P62140V9HW04
PPP1CB	NM_206876.2 link	c.521-8A>T		splice_region_variant, intron_variant	Intron 5 of 8		NP_996759.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PPP1CB	ENST00000395366.3 link	c.521-8A>T		splice_region_variant, intron_variant	Intron 4 of 7	1	NM_002709.3	ENSP00000378769.2		P62140

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.88e-7

AC:

AN:

1452946

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

723536

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:

33226

American (AMR)

AF:

0.00

AC:

AN:

44456

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26054

East Asian (EAS)

AF:

0.00

AC:

AN:

39610

South Asian (SAS)

AF:

0.00

AC:

AN:

85928

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53328

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5744

European-Non Finnish (NFE)

AF:

9.05e-7

AC:

AN:

1104510

Other (OTH)

AF:

0.00

AC:

AN:

60090

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), 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

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.69

CADD

Benign

(source)

DANN

Benign

0.66

PhyloP100

0.043

Mutation Taster

=100/0

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Benign

0.0012

dbscSNV1_RF

Benign

0.072

SpliceAI score (max)

0.0

Details are displayed if max score is > 0.2

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

Publications

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2-28783899-A-T

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over