chr18-3449779-G-C

Position:

• chr18-3449779-G-C

Variant summary

Our verdict is Benign. Variant got -14 ACMG points: 0P and 14B. BP4_Strong BP6_Moderate BS1 BS2

The XR_007066269.1(LOC124904237):​n.125+753C>G variant causes a intron, non coding transcript change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00245 in 985,552 control chromosomes in the GnomAD database, including 41 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Benign (★).

• Frequency:
  • Genomes: 𝑓 0.011 (28 hom., cov: 32)
  • Exomes 𝑓: 0.00086 (13 hom.)
• Consequence: LOC124904237 XR_007066269.1 intron, non_coding_transcript
• Clinical Significance: Benign criteria provided, single submitter B:1
• Conservation: PhyloP100: 1.39

Genes affected

LOC124904237 (HGNC:):

TGIF1 (HGNC:11776): (TGFB induced factor homeobox 1) The protein encoded by this gene is a member of the three-amino acid loop extension (TALE) superclass of atypical homeodomains. TALE homeobox proteins are highly conserved transcription regulators. This particular homeodomain binds to a previously characterized retinoid X receptor responsive element from the cellular retinol-binding protein II promoter. In addition to its role in inhibiting 9-cis-retinoic acid-dependent RXR alpha transcription activation of the retinoic acid responsive element, the protein is an active transcriptional co-repressor of SMAD2 and may participate in the transmission of nuclear signals during development and in the adult. Mutations in this gene are associated with holoprosencephaly type 4, which is a structural anomaly of the brain. Alternative splicing has been observed at this locus and multiple splice variants encoding distinct isoforms are described. [provided by RefSeq, Jul 2013]

ACMG classification

Verdict is Benign. Variant got -14 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.86).
• BP6: Variant 18-3449779-G-C is Benign according to our data. Variant chr18-3449779-G-C is described in ClinVar as [Benign]. Clinvar id is 889043.Status of the report is criteria_provided_single_submitter, 1 stars.
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.0112 (1704/152292) while in subpopulation AFR AF= 0.0388 (1613/41558). AF 95% confidence interval is 0.0372. There are 28 homozygotes in gnomad4. There are 794 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd4 at 28 gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
LOC124904237	XR_007066269.1	n.125+753C>G		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TGIF1	ENST00000405385.7	c.-336G>C		5_prime_UTR_variant	1/3	2
TGIF1	ENST00000401449.5	c.-44-6575G>C		intron_variant		2
TGIF1	ENST00000548489.6	c.-44-6575G>C		intron_variant		3

Frequencies

GnomAD3 genomes AF: 0.0112 AC: 1707 AN: 152178 Hom.: 27 Cov.: 32

Gnomad AFR AF: 0.0390

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00419

Gnomad ASJ AF: 0.000288

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000206

Gnomad OTH AF: 0.00574

GnomAD4 exome AF: 0.000856 AC: 713 AN: 833260 Hom.: 13 Cov.: 35 AF XY: 0.000863 AC XY: 332 AN XY: 384826

Gnomad4 AFR exome AF: 0.0371

Gnomad4 AMR exome AF: 0.00304

Gnomad4 ASJ exome AF: 0.000194

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000607

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000853

Gnomad4 OTH exome AF: 0.00194

GnomAD4 genome AF: 0.0112 AC: 1704 AN: 152292 Hom.: 28 Cov.: 32 AF XY: 0.0107 AC XY: 794 AN XY: 74468

Gnomad4 AFR AF: 0.0388

Gnomad4 AMR AF: 0.00418

Gnomad4 ASJ AF: 0.000288

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000206

Gnomad4 OTH AF: 0.00568

Alfa AF: 0.00881 Hom.: 3

Bravo AF: 0.0128

Asia WGS AF: 0.00115 AC: 4 AN: 3476

ClinVar

Significance: Benign

Submissions summary: Benign:1

Revision: criteria provided, single submitter

Submissions by phenotype

Holoprosencephaly 4 Benign:1

Benign, 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 and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.86
CADD	Benign	6.0
DANN	Benign	0.37

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: rs142599245; hg19: chr18-3449777;