18-70020624-T-A

Variant names:

• chr18-70020624-T-A
• rs2304378
• NM_173630.4:c.6144A>T

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 2P and 3B. PM2 BP4_Moderate BP7

The NM_173630.4(RTTN):​c.6144A>T​(p.Val2048Val) variant causes a synonymous 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. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. V2048V) has been classified as Benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: RTTN NM_173630.4 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.268
• Publications: 12 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: Likely_benign. The variant received -1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.34).
• BP7: Synonymous conserved (PhyloP=0.268 with no splicing effect.

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.6144A>T	p.Val2048Val	synonymous	Exon 45 of 49	NP_775901.3
	RTTN	NM_001318520.2		c.3408A>T	p.Val1136Val	synonymous	Exon 44 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.6144A>T	p.Val2048Val	synonymous	Exon 45 of 49	ENSP00000491507.1
	RTTN	ENST00000581161.5	TSL:1	n.*4458A>T		non_coding_transcript_exon	Exon 44 of 48	ENSP00000462926.1
	RTTN	ENST00000583043.5	TSL:1	n.*3415A>T		non_coding_transcript_exon	Exon 39 of 43	ENSP00000462733.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.34
CADD	Benign	2.8
DANN	Benign	0.79
PhyloP100		0.27

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: rs2304378; hg19: chr18-67687860;