20-8132651-G-C

Variant names:

• chr20-8132651-G-C
• rs764523154
• NM_015192.4:c.-1G>C

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 0P and 3B. BP4_Moderate BS1_Supporting

The NM_015192.4(PLCB1):​c.-1G>C variant causes a 5 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000617 in 1,457,570 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: PLCB1 NM_015192.4 5_prime_UTR
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.42
• Publications: 1 publications found

Genes affected

PLCB1 (HGNC:15917): (phospholipase C beta 1) The protein encoded by this gene catalyzes the formation of inositol 1,4,5-trisphosphate and diacylglycerol from phosphatidylinositol 4,5-bisphosphate. This reaction uses calcium as a cofactor and plays an important role in the intracellular transduction of many extracellular signals. This gene is activated by two G-protein alpha subunits, alpha-q and alpha-11. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]

PLCB1 Gene-Disease associations (from GenCC):

• genetic developmental and epileptic encephalopathy

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• developmental and epileptic encephalopathy, 12

  Inheritance: AR Classification: STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• infantile spasms

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• malignant migrating partial seizures of infancy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_benign. The variant received -3 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.37).
• BS1: Variant frequency is greater than expected in population sas. GnomAdExome4 allele frequency = 0.00000617 (9/1457570) while in subpopulation SAS AF = 0.0000932 (8/85840). AF 95% confidence interval is 0.000046. There are 0 homozygotes in GnomAdExome4. There are 7 alleles in the male GnomAdExome4 subpopulation. Median coverage is 30. This position passed quality control check. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PLCB1	NM_015192.4	c.-1G>C		5_prime_UTR_variant	Exon 1 of 32	ENST00000338037.11	NP_056007.1
PLCB1	NM_182734.3	c.-1G>C		5_prime_UTR_variant	Exon 1 of 33		NP_877398.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PLCB1	ENST00000338037.11	c.-1G>C		5_prime_UTR_variant	Exon 1 of 32	1	NM_015192.4	ENSP00000338185.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.0000165 AC: 4 AN: 243126 AF XY: 0.0000151

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000617 AC: 9 AN: 1457570 Hom.: 0 Cov.: 30 AF XY: 0.00000965 AC XY: 7 AN XY: 725204

African (AFR) AF: 0.00 AC: 0 AN: 33160

American (AMR) AF: 0.00 AC: 0 AN: 44456

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25982

East Asian (EAS) AF: 0.00 AC: 0 AN: 39464

South Asian (SAS) AF: 0.0000932 AC: 8 AN: 85840

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52918

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5678

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1109940

Other (OTH) AF: 0.0000166 AC: 1 AN: 60132

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Developmental and epileptic encephalopathy, 12 Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.37
CADD	Benign	22
DANN	Benign	0.93
PhyloP100		1.4
PromoterAI		0.018	Neutral

Splicing

Name	Calibrated prediction	Score	Prediction
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

Other links and lift over

dbSNP: rs764523154; hg19: chr20-8113298;