chrX-154420212-G-A

Position:

• chrX-154420212-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_000116.5(TAFAZZIN):​c.647G>A​(p.Gly216Glu) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 23)
• Consequence: TAFAZZIN NM_000116.5 missense, splice_region
• Scores: Splicing: ADA: 0.9991
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 8.92

Genes affected

TAFAZZIN (HGNC:11577): (tafazzin, phospholipid-lysophospholipid transacylase) This gene encodes a protein that is expressed at high levels in cardiac and skeletal muscle. Mutations in this gene have been associated with a number of clinical disorders including Barth syndrome, dilated cardiomyopathy (DCM), hypertrophic DCM, endocardial fibroelastosis, and left ventricular noncompaction (LVNC). Multiple transcript variants encoding different isoforms have been described. A long form and a short form of each of these isoforms is produced; the short form lacks a hydrophobic leader sequence and may exist as a cytoplasmic protein rather than being membrane-bound. Other alternatively spliced transcripts have been described but the full-length nature of all these transcripts is not known. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a topological_domain Mitochondrial intermembrane (size 226) in uniprot entity TAZ_HUMAN there are 6 pathogenic changes around while only 0 benign (100%) in NM_000116.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TAFAZZIN	NM_000116.5	c.647G>A	p.Gly216Glu	missense_variant, splice_region_variant	9/11	ENST00000601016.6	NP_000107.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TAFAZZIN	ENST00000601016.6	c.647G>A	p.Gly216Glu	missense_variant, splice_region_variant	9/11	1	NM_000116.5	ENSP00000469981

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 23

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

3-Methylglutaconic aciduria type 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 29, 2020

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. This variant disrupts the p.Gly216 amino acid residue in TAZ. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 9382096, 24887148, 23656970, 23361305, 21932011). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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: "Not Available"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Not Available"). This variant has not been reported in the literature in individuals with TAZ-related conditions. ClinVar contains an entry for this variant (Variation ID: 655314). This variant is not present in population databases (ExAC no frequency). This sequence change replaces glycine with glutamic acid at codon 216 of the TAZ protein (p.Gly216Glu). The glycine residue is moderately conserved and there is a moderate physicochemical difference between glycine and glutamic acid. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.68	D
BayesDel_noAF	Pathogenic	0.74
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.74	.;.;.;D;.
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.90	D;D;D;D;T
M_CAP	Pathogenic	0.97	D
MetaRNN	Pathogenic	0.93	D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.7	.;.;.;M;.
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Uncertain	0.75	T
PROVEAN	Benign	-1.5	.;.;.;.;N
REVEL	Pathogenic	0.97
Sift	Uncertain	0.0040	.;.;.;.;D
Sift4G	Uncertain	0.030	D;D;T;D;T
Polyphen		1.0	D;D;D;D;.
Vest4		0.98
MutPred		0.72		.;.;.;Loss of catalytic residue at D219 (P = 0.0235);.;
MVP		1.0
ClinPred		0.97	D
GERP RS		5.2
Varity_R		0.83
gMVP		1.0

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.87
SpliceAI score (max)		0.17		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: rs727504431; hg19: chrX-153648551;