2-27447526-C-T

Variant names:

• chr2-27447526-C-T
• rs779801761
• NM_015662.3:c.4648G>A

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_015662.3(IFT172):​c.4648G>A​(p.Val1550Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000616 in 1,461,730 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: IFT172 NM_015662.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.227

Genes affected

IFT172 (HGNC:30391): (intraflagellar transport 172) This gene encodes a subunit of the intraflagellar transport subcomplex IFT-B. Subcomplexes IFT-A and IFT-B are necessary for ciliary assembly and maintenance. Mutations in this gene have been associated with skeletal ciliopathies, with or without polydactyly, such as such short-rib thoracic dysplasias 1, 9 or 10. [provided by RefSeq, Mar 2014]

ACMG classification

Verdict is Likely_benign. Variant got -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.03126055).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
IFT172	NM_015662.3	c.4648G>A	p.Val1550Ile	missense_variant	Exon 42 of 48	ENST00000260570.8	NP_056477.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
IFT172	ENST00000260570.8	c.4648G>A	p.Val1550Ile	missense_variant	Exon 42 of 48	1	NM_015662.3	ENSP00000260570.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000616 AC: 9 AN: 1461730 Hom.: 0 Cov.: 31 AF XY: 0.00000550 AC XY: 4 AN XY: 727166

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000809

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Short-rib thoracic dysplasia 10 with or without polydactyly;C4225342:Retinitis pigmentosa 71 Uncertain:1

Jan 06, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces valine, which is neutral and non-polar, with isoleucine, which is neutral and non-polar, at codon 1550 of the IFT172 protein (p.Val1550Ile). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with IFT172-related conditions. ClinVar contains an entry for this variant (Variation ID: 567601). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt IFT172 protein function with a negative predictive value of 95%. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.067
BayesDel_addAF	Benign	-0.34	T
BayesDel_noAF	Benign	-0.72
CADD	Benign	1.9
DANN	Benign	0.81
DEOGEN2	Benign	0.095	T
Eigen	Benign	-1.3
Eigen_PC	Benign	-1.2
FATHMM_MKL	Benign	0.084	N
LIST_S2	Benign	0.69	T
M_CAP	Benign	0.0070	T
MetaRNN	Benign	0.031	T
MetaSVM	Benign	-0.99	T
MutationAssessor	Benign	0.93	L
PrimateAI	Benign	0.27	T
PROVEAN	Benign	-0.27	N
REVEL	Benign	0.0090
Sift	Benign	0.54	T
Sift4G	Benign	0.51	T
Polyphen		0.0020	B
Vest4		0.17
MutPred		0.21		Loss of helix (P = 0.0237);
MVP		0.072
MPC		0.14
ClinPred		0.038	T
GERP RS		-4.5
Varity_R		0.030
gMVP		0.036

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs779801761; hg19: chr2-27670393;