3-3144632-AAAAT-A

Variant names:

• chr3-3144632-AAAAT-A
• rs1705869868
• NM_182916.3:c.533_536delATAA

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_182916.3(TRNT1):​c.533_536delATAA​(p.Asn178ArgfsTer21) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000139 in 1,434,990 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: 0.0000014 (0 hom.)
• Consequence: TRNT1 NM_182916.3 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.31
• Publications: 0 publications found

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]

CRBN Gene-Disease associations (from GenCC):

• intellectual disability

  Inheritance: AR Classification: MODERATE Submitted by: ClinGen
• autosomal recessive non-syndromic intellectual disability

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• intellectual disability, autosomal recessive 2

  Inheritance: AR Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae), G2P

ACMG classification

Our verdict: Pathogenic. The variant received 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 3-3144632-AAAAT-A is Pathogenic according to our data. Variant chr3-3144632-AAAAT-A is described in ClinVar as [Pathogenic]. Clinvar id is 3682974.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TRNT1	NM_182916.3	c.533_536delATAA	p.Asn178ArgfsTer21	frameshift_variant	Exon 5 of 8	ENST00000251607.11	NP_886552.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TRNT1	ENST00000251607.11	c.533_536delATAA	p.Asn178ArgfsTer21	frameshift_variant	Exon 5 of 8	1	NM_182916.3	ENSP00000251607.6

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000139 AC: 2 AN: 1434990 Hom.: 0 AF XY: 0.00000280 AC XY: 2 AN XY: 714174

African (AFR) AF: 0.00 AC: 0 AN: 32670

American (AMR) AF: 0.00 AC: 0 AN: 43284

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25524

East Asian (EAS) AF: 0.00 AC: 0 AN: 39092

South Asian (SAS) AF: 0.0000118 AC: 1 AN: 84516

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52818

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5672

European-Non Finnish (NFE) AF: 9.16e-7 AC: 1 AN: 1092276

Other (OTH) AF: 0.00 AC: 0 AN: 59138

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

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

Jun 05, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Asn178Argfs*21) 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

Name	Calibrated prediction	Score	Prediction
PhyloP100		7.3

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

Other links and lift over

dbSNP: rs1705869868; hg19: chr3-3186316;