rs878854168

Positions:

• chr4-15596207-G-A
• chr4-15596207-G-C
• chr4-15596207-G-T

Variant summary

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

The NM_001378615.1(CC2D2A):​c.4437G>A​(p.Gln1479=) variant causes a splice region, synonymous change. The variant allele was found at a frequency of 0.000000737 in 1,357,608 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 7.4e-7 (0 hom.)
• Consequence: CC2D2A NM_001378615.1 splice_region, synonymous
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.38

Genes affected

CC2D2A (HGNC:29253): (coiled-coil and C2 domain containing 2A) This gene encodes a coiled-coil and calcium binding domain protein that appears to play a critical role in cilia formation. Mutations in this gene cause Meckel syndrome type 6, as well as Joubert syndrome type 9. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Sep 2009]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

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

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CC2D2A	NM_001378615.1	c.4437G>A	p.Gln1479=	splice_region_variant, synonymous_variant	34/37	ENST00000424120.6	NP_001365544.1
CC2D2A	NM_001080522.2	c.4437G>A	p.Gln1479=	splice_region_variant, synonymous_variant	35/38		NP_001073991.2
CC2D2A	NM_001378617.1	c.4290G>A	p.Gln1430=	splice_region_variant, synonymous_variant	32/35		NP_001365546.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CC2D2A	ENST00000424120.6	c.4437G>A	p.Gln1479=	splice_region_variant, synonymous_variant	34/37	5	NM_001378615.1	ENSP00000403465	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 7.37e-7 AC: 1 AN: 1357608 Hom.: 0 Cov.: 29 AF XY: 0.00 AC XY: 0 AN XY: 668050

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: 9.42e-7

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

Meckel-Gruber syndrome;C0431399:Familial aplasia of the vermis Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 13, 2022

This sequence change affects codon 1479 of the CC2D2A mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the CC2D2A protein. This variant also falls at the last nucleotide of exon 35, which is part of the consensus splice site for this exon. This variant is not present in population databases (gnomAD no frequency). 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. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 1023694). This variant has not been reported in the literature in individuals affected with CC2D2A-related conditions. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.36
CADD	Benign	22
DANN	Benign	0.85

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.91		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.91		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs878854168; hg19: chr4-15597830;