21-32601906-CT-C

Variant names:

• chr21-32601906-CT-C
• rs2038749156
• NM_021254.4:c.829delA

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PVS1_Moderate PM2

The NM_021254.4(CFAP298):​c.829delA​(p.Arg277AspfsTer6) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,460,762 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: CFAP298 NM_021254.4 frameshift
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 3.51

Genes affected

CFAP298 (HGNC:1301): (cilia and flagella associated protein 298) This gene encodes a protein that plays a critical role in dynein arm assembly and motile cilia function. Mutations in this gene result in primary ciliary dyskinesia. Naturally occuring readthrough transcription occurs from this locus to the downstream t-complex 10 like (TCP10L) gene. [provided by RefSeq, Apr 2017]

CFAP298-TCP10L (HGNC:54636): (CFAP298-TCP10L readthrough) This locus represents naturally occurring readthrough transcription between the neighboring chromosome 21 open reading frame 59 (C21orf59) and TCP10L (t-complex 10 like) genes on chromosome 21. Readthrough transcripts may encode a fusion protein that shares sequence identity with each individual gene product. [provided by RefSeq, Apr 2017]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.0504 CDS is truncated, and there are 0 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CFAP298	NM_021254.4	c.829delA	p.Arg277AspfsTer6	frameshift_variant	Exon 7 of 7	ENST00000290155.8	NP_067077.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CFAP298	ENST00000290155.8	c.829delA	p.Arg277AspfsTer6	frameshift_variant	Exon 7 of 7	1	NM_021254.4	ENSP00000290155.3
CFAP298-TCP10L	ENST00000673807.1	c.666+1254delA		intron_variant	Intron 5 of 7			ENSP00000501088.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1460762 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 726782

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Primary ciliary dyskinesia 26 Uncertain:1

Sep 23, 2024

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as VUS-3A. Following criteria are met: 0102 - Loss of function is a known mechanism of disease in this gene and is associated with primary ciliary dyskinesia 26 (MIM#615500) (PMIDs: 24094744, 26904945). (I) 0106 - This gene is associated with autosomal recessive disease. (I) 0205 - Variant is predicted to result in a truncated protein (premature termination codon is NOT located at least 54 nucleotides upstream of the final exon-exon junction) with less than 1/3 of the protein sequence affected. (SP) 0251 - This variant is heterozygous. (I) 0301 - Variant is absent from gnomAD (both v2 and v3). (SP) 0600 - Variant is expected to disrupt the CFAP298 domain (DECIPHER). (I) 0710 - Another protein truncating variant comparable to the one identified in this case has inconclusive previous evidence for pathogenicity. A downstream truncating variant has been reported in ClinVar once as a variant of unknown significance. (I) 0809 - Previous evidence of pathogenicity for this variant is inconclusive. This variant has been reported once in ClinVar as a variant of unknown significance. (I) 0905 - No published segregation evidence has been identified for this variant. (I) 1007 - No published functional evidence has been identified for this variant. (I) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

not provided Uncertain:1

Jul 21, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant has not been reported in the literature in individuals affected with CFAP298-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Arg277Aspfs*6) in the CFAP298 gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 14 amino acid(s) of the CFAP298 protein. ClinVar contains an entry for this variant (Variation ID: 1025340). 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. Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. -

Computational scores

Source: dbNSFP v4.3

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: rs2038749156; hg19: chr21-33974216;