chr12-110127514-T-C

Position:

• chr12-110127514-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_014055.4(IFT81):​c.134T>C​(p.Ile45Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000277 in 1,445,348 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000028 (0 hom.)
• Consequence: IFT81 NM_014055.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts P:1 U:2
• Conservation: PhyloP100: 7.67

Genes affected

IFT81 (HGNC:14313): (intraflagellar transport 81) The protein encoded by this gene, together with IFT74, forms a tubulin-binding module of intraflagellar transport complex B. This module is involved in transport of tubulin within the cilium, and the encoded protein is required for ciliogenesis. Mutations in this gene are a cause of short-rib polydactyly syndromes. [provided by RefSeq, Dec 2016]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.807

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
IFT81	NM_014055.4	c.134T>C	p.Ile45Thr	missense_variant	2/19	ENST00000242591.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
IFT81	ENST00000242591.10	c.134T>C	p.Ile45Thr	missense_variant	2/19	1	NM_014055.4	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.00000436 AC: 1 AN: 229216 Hom.: 0 AF XY: 0.00000806 AC XY: 1 AN XY: 124026

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000391

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000277 AC: 4 AN: 1445348 Hom.: 0 Cov.: 30 AF XY: 0.00000139 AC XY: 1 AN XY: 718442

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000253

Gnomad4 SAS exome AF: 0.0000122

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000181

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Short-rib thoracic dysplasia 19 with or without polydactyly Pathogenic:1 Uncertain:1

Likely pathogenic, no assertion criteria provided	clinical testing	Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital	Jan 30, 2022	This novel mis-sense variant is present in compound heterozygous state with another stop gain variant c.1441C>T (p.R481X) in IFT81 gene. The allele frequency is 0.0004% in gnomAD (aggregated) database. In-silico bioinformatic software predict this variant by mutation taster as Disease causing and SIFT & PROVEAN as Damaging. Phenotype observed in the proband was rhizo-mesomelic shortening of all four limbs, simian crease in both hands, large and dolicocephalic skull and mesomelia in lower limbs. Short rib thoracic dysplasia 19 with or without polydactyly is an autosomal recessive disorder and can be caused by Homozygous or Compound heterozygous variants. Based on phenotypic overall and identified variant we classify this as likely pathogenic variant. -
Uncertain significance, criteria provided, single submitter	clinical testing	Kasturba Medical College, Manipal, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India	Feb 04, 2022	- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 15, 2022

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. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt IFT81 protein function. ClinVar contains an entry for this variant (Variation ID: 1338762). This variant has not been reported in the literature in individuals affected with IFT81-related conditions. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change replaces isoleucine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 45 of the IFT81 protein (p.Ile45Thr). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.31
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.37
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Benign	0.36	.;T;T;.
Eigen	Pathogenic	0.91
Eigen_PC	Pathogenic	0.88
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.95	D;.;D;D
M_CAP	Uncertain	0.19	D
MetaRNN	Pathogenic	0.81	D;D;D;D
MetaSVM	Uncertain	0.51	D
MutationAssessor	Uncertain	2.9	M;M;M;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.74	T
PROVEAN	Uncertain	-4.2	D;D;D;D
REVEL	Pathogenic	0.82
Sift	Uncertain	0.0020	D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D
Polyphen		1.0	D;D;D;.
Vest4		0.91
MutPred		0.46		Loss of stability (P = 0.0047);Loss of stability (P = 0.0047);Loss of stability (P = 0.0047);Loss of stability (P = 0.0047);
MVP		0.93
MPC		0.67
ClinPred		0.98	D
GERP RS		6.1
Varity_R		0.72
gMVP		0.74

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: rs1227213671; hg19: chr12-110565319;