3-3144667-CAG-C

Position:

• chr3-3144667-CAG-C

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_182916.3(TRNT1):​c.569_570delGA​(p.Arg190fs) variant causes a frameshift change. The variant allele was found at a frequency of 0.00000774 in 1,420,436 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000077 (0 hom.)
• Consequence: TRNT1 NM_182916.3 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 4.66

Genes affected

TRNT1 (HGNC:17341): (tRNA nucleotidyl transferase 1) The protein encoded by this gene is a CCA-adding enzyme which belongs to the tRNA nucleotidyltransferase/poly(A) polymerase family. This essential enzyme functions by catalyzing the addition of the conserved nucleotide triplet CCA to the 3' terminus of tRNA molecules. Mutations in this gene result in sideroblastic anemia with B-cell immunodeficiency, periodic fevers, and developmental delay. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Dec 2014]

CRBN (HGNC:30185): (cereblon) This gene encodes a protein related to the Lon protease protein family. In rodents and other mammals this gene product is found in the cytoplasm localized with a calcium channel membrane protein, and is thought to play a role in brain development. Mutations in this gene are associated with autosomal recessive nonsyndromic cognitive disability. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Mar 2010]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 3-3144667-CAG-C is Pathogenic according to our data. Variant chr3-3144667-CAG-C is described in ClinVar as [Pathogenic]. Clinvar id is 1904390.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TRNT1	NM_182916.3	c.569_570delGA	p.Arg190fs	frameshift_variant	5/8	ENST00000251607.11	NP_886552.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TRNT1	ENST00000251607.11	c.569_570delGA	p.Arg190fs	frameshift_variant	5/8	1	NM_182916.3	ENSP00000251607.6

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000774 AC: 11 AN: 1420436 Hom.: 0 AF XY: 0.0000113 AC XY: 8 AN XY: 707218

Gnomad4 AFR exome AF: 0.0000310

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000721

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000370

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000756

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Congenital sideroblastic anemia-B-cell immunodeficiency-periodic fever-developmental delay syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 29, 2024

This sequence change creates a premature translational stop signal (p.Arg190Asnfs*7) in the TRNT1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in TRNT1 are known to be pathogenic (PMID: 25193871). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TRNT1-related conditions. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

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: rs1289523507; hg19: chr3-3186351;