2-219570240-G-A

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 2P and 5B. PM2 BP4_Strong BP7

The NM_015311.3(OBSL1):c.993C>T(p.Ala331=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000141 in 1,421,238 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 (★). Synonymous variant affecting the same amino acid position (i.e. A331A) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: OBSL1 NM_015311.3 synonymous
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -5.01

Genes affected

OBSL1 (HGNC:29092): (obscurin like cytoskeletal adaptor 1) Cytoskeletal adaptor proteins function in linking the internal cytoskeleton of cells to the cell membrane. This gene encodes a cytoskeletal adaptor protein, which is a member of the Unc-89/obscurin family. The protein contains multiple N- and C-terminal immunoglobulin (Ig)-like domains and a central fibronectin type 3 domain. Mutations in this gene cause 3M syndrome type 2. Alternatively spliced transcript variants encoding different isoforms have been found in this gene. [provided by RefSeq, Mar 2010]

INHA (HGNC:6065): (inhibin subunit alpha) This gene encodes a member of the TGF-beta (transforming growth factor-beta) superfamily of proteins. The encoded preproprotein is proteolytically processed to generate multiple peptide products, including the alpha subunit of the inhibin A and B protein complexes. These complexes negatively regulate follicle stimulating hormone secretion from the pituitary gland. Inhibins have also been implicated in regulating numerous cellular processes including cell proliferation, apoptosis, immune response and hormone secretion. Mutations in this gene may be associated with male infertility and premature ovarian failure in female human patients. [provided by RefSeq, Aug 2016]

ACMG classification

Verdict is Likely_benign. Variant got -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.87).
• BP7: Synonymous conserved (PhyloP=-5.01 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
OBSL1	NM_015311.3	c.993C>T	p.Ala331=	synonymous_variant	1/21	ENST00000404537.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
OBSL1	ENST00000404537.6	c.993C>T	p.Ala331=	synonymous_variant	1/21	1	NM_015311.3	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000475 AC: 1 AN: 210468 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 114154

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000312

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS 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: 0.00000141 AC: 2 AN: 1421238 Hom.: 0 Cov.: 30 AF XY: 0.00000143 AC XY: 1 AN XY: 701382

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000473

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.: 33

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

3M syndrome 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

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	-0.87
Cadd	Benign	0.15
Dann	Benign	0.94
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: rs771686909; hg19: chr2-220434962;