18-70004236-G-A

Position:

• chr18-70004236-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_173630.4(RTTN):​c.6596C>T​(p.Thr2199Ile) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 14/20 in silico tools predict a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 31)
• Consequence: RTTN NM_173630.4 missense, splice_region
• Scores: Splicing: ADA: 0.0003603
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.852

Genes affected

RTTN (HGNC:18654): (rotatin) This gene encodes a large protein whose specific function is unknown. Absence of the orthologous protein in mouse results in embryonic lethality with deficient axial rotation, abnormal differentiation of the neural tube, and randomized looping of the heart tube during development. In human, mutations in this gene are associated with polymicrogyria with seizures. In human fibroblasts this protein localizes at the ciliary basal bodies. Given the intracellular localization of this protein and the phenotypic effects of mutations, this gene is suspected of playing a role in the maintenance of normal ciliary structure which in turn effects the developmental process of left-right organ specification, axial rotation, and perhaps notochord development. [provided by RefSeq, Jan 2013]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.10258213).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
RTTN	NM_173630.4	c.6596C>T	p.Thr2199Ile	missense_variant, splice_region_variant	49/49	ENST00000640769.2	NP_775901.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
RTTN	ENST00000640769.2	c.6596C>T	p.Thr2199Ile	missense_variant, splice_region_variant	49/49	2	NM_173630.4	ENSP00000491507	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 28

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 26, 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. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. ClinVar contains an entry for this variant (Variation ID: 1373928). This variant has not been reported in the literature in individuals affected with RTTN-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces threonine, which is neutral and polar, with isoleucine, which is neutral and non-polar, at codon 2199 of the RTTN protein (p.Thr2199Ile). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.12
BayesDel_addAF	Benign	-0.19	T
BayesDel_noAF	Benign	-0.51
CADD	Benign	14
DANN	Uncertain	0.99
DEOGEN2	Benign	0.12	T;.
Eigen	Benign	-0.15
Eigen_PC	Benign	-0.18
FATHMM_MKL	Benign	0.61	D
LIST_S2	Benign	0.75	T;T
M_CAP	Benign	0.016	T
MetaRNN	Benign	0.10	T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	2.0	M;.
MutationTaster	Benign	1.0	D;N
PrimateAI	Benign	0.41	T
Polyphen		0.77	P;.
MutPred		0.23		Gain of catalytic residue at P2201 (P = 0.0305);.;
ClinPred		0.60	D
GERP RS		3.3
Varity_R		0.055
gMVP		0.17

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.00036
dbscSNV1_RF	Benign	0.046
SpliceAI score (max)		0.15		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr18-67671472;