3-94049513-C-G

Variant summary

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

The NM_001174150.2(ARL13B):c.1132C>G(p.Pro378Ala) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000138 in 1,449,170 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P378L) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: ARL13B NM_001174150.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.64

Genes affected

ARL13B (HGNC:25419): (ADP ribosylation factor like GTPase 13B) This gene encodes a member of the ADP-ribosylation factor-like family. The encoded protein is a small GTPase that contains both N-terminal and C-terminal guanine nucleotide-binding motifs. This protein is localized in the cilia and plays a role in cilia formation and in maintenance of cilia. Mutations in this gene are the cause of Joubert syndrome 8. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Mar 2010]

DHFR2 (HGNC:27309): (dihydrofolate reductase 2) Enables dihydrofolate reductase activity and mRNA binding activity. Involved in tetrahydrofolate metabolic process and thymidine biosynthetic process. Located in mitochondrial inner membrane and mitochondrial matrix. [provided by Alliance of Genome Resources, Apr 2022]

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=0.1304476).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ARL13B	NM_001174150.2	c.1132C>G	p.Pro378Ala	missense_variant	8/10	ENST00000394222.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ARL13B	ENST00000394222.8	c.1132C>G	p.Pro378Ala	missense_variant	8/10	1	NM_001174150.2	P1

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD3 exomes AF: 0.00000400 AC: 1 AN: 250308 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135330

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: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000164

GnomAD4 exome AF: 0.00000138 AC: 2 AN: 1449170 Hom.: 0 Cov.: 29 AF XY: 0.00000139 AC XY: 1 AN XY: 721448

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: 9.08e-7

Gnomad4 OTH exome AF: 0.0000167

GnomAD4 genome Cov.: 30

Alfa AF: 0.000111 Hom.: 0

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Joubert syndrome 8 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Apr 12, 2022

This sequence change replaces proline, which is neutral and non-polar, with alanine, which is neutral and non-polar, at codon 378 of the ARL13B protein (p.Pro378Ala). This variant is present in population databases (rs770186628, gnomAD no frequency). This variant has not been reported in the literature in individuals affected with ARL13B-related conditions. 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. 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	0.070
BayesDel_addAF	Benign	-0.10	T
BayesDel_noAF	Benign	-0.39
Cadd	Benign	17
Dann	Benign	0.49
Eigen	Benign	-0.48
Eigen_PC	Benign	-0.54
FATHMM_MKL	Benign	0.19	N
LIST_S2	Benign	0.74	T;T;.;T
M_CAP	Benign	0.021	T
MetaRNN	Benign	0.13	T;T;T;T
MetaSVM	Benign	-0.90	T
MutationTaster	Benign	1.0	N;N;N;N;N
PrimateAI	Benign	0.40	T
PROVEAN	Benign	-0.61	N;N;N;N
REVEL	Benign	0.085
Sift	Benign	0.20	T;T;T;T
Sift4G	Benign	1.0	T;T;T;T
Polyphen		0.95, 0.43	.;P;B;B
Vest4		0.38
MutPred		0.20		.;.;Loss of glycosylation at P377 (P = 5e-04);Loss of glycosylation at P377 (P = 5e-04);
MVP		0.57
MPC		0.073
ClinPred		0.060	T
GERP RS		2.3
Varity_R		0.029
gMVP		0.16

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: rs770186628; hg19: chr3-93768357;