18-70197682-T-A

Variant names:

• chr18-70197682-T-A
• rs12956068
• NM_173630.4:c.635A>T

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_173630.4(RTTN):​c.635A>T​(p.Asp212Val) variant causes a missense change. The variant allele was found at a frequency of 0.00000137 in 1,461,640 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. D212A) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: RTTN NM_173630.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 6.21
• Publications: 0 publications found

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]

RTTN Gene-Disease associations (from GenCC):

• microcephalic primordial dwarfism due to RTTN deficiency

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Labcorp Genetics (formerly Invitae)
• bilateral generalized polymicrogyria

  Inheritance: AR Classification: MODERATE Submitted by: Ambry Genetics

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

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

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_173630.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	RTTN	NM_173630.4	MANE Select	c.635A>T	p.Asp212Val	missense	Exon 6 of 49	NP_775901.3
	RTTN	NM_001318520.2		c.-1919A>T		5_prime_UTR_premature_start_codon_gain	Exon 6 of 48	NP_001305449.1
	RTTN	NM_001318520.2		c.-1919A>T		5_prime_UTR	Exon 6 of 48	NP_001305449.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	RTTN	ENST00000640769.2	TSL:2 MANE Select	c.635A>T	p.Asp212Val	missense	Exon 6 of 49	ENSP00000491507.1
	RTTN	ENST00000581161.5	TSL:1	n.635A>T		non_coding_transcript_exon	Exon 6 of 48	ENSP00000462926.1
	RTTN	ENST00000583043.5	TSL:1	n.5A>T		non_coding_transcript_exon	Exon 1 of 43	ENSP00000462733.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461640 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 727136

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33476

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26130

East Asian (EAS) AF: 0.00 AC: 0 AN: 39670

South Asian (SAS) AF: 0.00 AC: 0 AN: 86248

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1111826

Other (OTH) AF: 0.00 AC: 0 AN: 60382

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.75
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.15
CADD	Uncertain	24
DANN	Benign	0.93
DEOGEN2	Uncertain	0.63	D
Eigen	Uncertain	0.51
Eigen_PC	Uncertain	0.42
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.92	D
M_CAP	Uncertain	0.15	D
MetaRNN	Uncertain	0.63	D
MetaSVM	Benign	-0.29	T
MutationAssessor	Uncertain	2.7	M
PhyloP100		6.2
PrimateAI	Uncertain	0.62	T
PROVEAN	Pathogenic	-5.0	D
REVEL	Uncertain	0.45
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.92
MutPred		0.51		Gain of methylation at K211 (P = 0.0283)
MVP		0.38
MPC		0.49
ClinPred		0.97	D
GERP RS		3.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.67
gMVP		0.81
Mutation Taster		=85/15	polymorphism

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

Other links and lift over

dbSNP: rs12956068; hg19: chr18-67864918;