17-2638310-C-T

Position:

• chr17-2638310-C-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000430.4(PAFAH1B1):​c.22C>T​(p.Arg8Ter) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: PAFAH1B1 NM_000430.4 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: 2.86

Genes affected

PAFAH1B1 (HGNC:8574): (platelet activating factor acetylhydrolase 1b regulatory subunit 1) This locus was identified as encoding a gene that when mutated or lost caused the lissencephaly associated with Miller-Dieker lissencephaly syndrome. This gene encodes the non-catalytic alpha subunit of the intracellular Ib isoform of platelet-activating factor acteylhydrolase, a heterotrimeric enzyme that specifically catalyzes the removal of the acetyl group at the SN-2 position of platelet-activating factor (identified as 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine). Two other isoforms of intracellular platelet-activating factor acetylhydrolase exist: one composed of multiple subunits, the other, a single subunit. In addition, a single-subunit isoform of this enzyme is found in serum. [provided by RefSeq, Apr 2009]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 112 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 17-2638310-C-T is Pathogenic according to our data. Variant chr17-2638310-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 8081.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PAFAH1B1	NM_000430.4	c.22C>T	p.Arg8Ter	stop_gained	2/11	ENST00000397195.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PAFAH1B1	ENST00000397195.10	c.22C>T	p.Arg8Ter	stop_gained	2/11	1	NM_000430.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0;AS_VQSR AF: 0.00 AC: 0 AN: 1460466 Hom.: 0 Cov.: 29 AF XY: 0.00 AC XY: 0 AN XY: 726578

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Lissencephaly due to LIS1 mutation Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Institute of Human Genetics, University of Leipzig Medical Center	Dec 06, 2023	Criteria applied: PVS1, PM2_SUP, PS4_MOD. This variant was detected in a mosaic state (allele fraction in blood 0.12) -
Pathogenic, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Mar 31, 2014	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Oct 28, 2003	- -

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Apr 07, 2024	Previously reported as a mosaic variant in an individual with subcortical band heterotopia, and in the heterozygous state in individuals with lissencephaly (PMID: 14581661, 29671837, 34979677); Nonsense variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 32366993, 15719169, 29671837, 22129557, 33484635, 33911214, 34979677, 14581661) -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Dec 02, 2021	For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 8081). This premature translational stop signal has been observed in individual(s) with lissencephaly (PMID: 14581661, 29671837). This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Arg8*) in the PAFAH1B1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in PAFAH1B1 are known to be pathogenic (PMID: 1671808, 11115846, 14581661). -

Lissencephaly Pathogenic:1

Likely pathogenic, no assertion criteria provided

research

University of Washington Center for Mendelian Genomics, University of Washington

-

- -

Subcortical band heterotopia Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Oct 28, 2003

- -

Intellectual disability Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Institute of Human Genetics, University of Leipzig Medical Center

Aug 03, 2020

The variant c.22C>T, p.(Arg8*) was identified in an individual with neurodevelopmental disorder (NDD) and classified as Likely pathogenic according to ACMG guidelines. Inheritance for this variant was mosaic (12-13% allele frequency).The variant likely explains the NDD in this individual. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	42
DANN	Uncertain	1.0
Eigen	Pathogenic	0.81
Eigen_PC	Pathogenic	0.69
FATHMM_MKL	Uncertain	0.82	D
MutationTaster	Benign	1.0	A;A
Vest4		0.94
GERP RS		5.3
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

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

Publications

LitVar

Other links and lift over

dbSNP: rs121434489; hg19: chr17-2541604;