3-3144652-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_182916.3(TRNT1):c.550G>A(p.Val184Ile) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: TRNT1 NM_182916.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.77

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 Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TRNT1	NM_182916.3	c.550G>A	p.Val184Ile	missense_variant	5/8	ENST00000251607.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TRNT1	ENST00000251607.11	c.550G>A	p.Val184Ile	missense_variant	5/8	1	NM_182916.3	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Mar 25, 2019

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with TRNT1-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces valine with isoleucine at codon 184 of the TRNT1 protein (p.Val184Ile). The valine residue is highly conserved and there is a small physicochemical difference between valine and isoleucine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.23
BayesDel_addAF	Benign	0.0081	T
BayesDel_noAF	Benign	-0.23
Cadd	Uncertain	23
Dann	Uncertain	1.0
DEOGEN2	Benign	0.072	T;.
Eigen	Pathogenic	0.70
Eigen_PC	Pathogenic	0.75
FATHMM_MKL	Pathogenic	0.99	D
M_CAP	Benign	0.013	T
MetaRNN	Uncertain	0.63	D;D
MetaSVM	Benign	-0.91	T
MutationAssessor	Benign	1.6	L;L
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.49	T
PROVEAN	Benign	-0.98	N;N
REVEL	Benign	0.17
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		0.93	P;D
Vest4		0.72
MutPred		0.59		Gain of catalytic residue at V184 (P = 0.0192);Gain of catalytic residue at V184 (P = 0.0192);
MVP		0.37
MPC		0.024
ClinPred		0.95	D
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.48
gMVP		0.75

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: rs1705871121; hg19: chr3-3186336;