19-29702978-CT-C

Position:

• chr19-29702978-CT-C

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PVS1_Strong PM2 PP3_Moderate PP5

The NM_031448.6(C19orf12):​c.161-2del variant causes a splice acceptor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,856 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: C19orf12 NM_031448.6 splice_acceptor
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:1
• Conservation: PhyloP100: 7.36

Genes affected

C19orf12 (HGNC:25443): (chromosome 19 open reading frame 12) This gene encodes a small transmembrane protein. Mutations in this gene are a cause of neurodegeneration with brain iron accumulation-4 (NBIA4), but the specific function of the encoded protein is unknown. Alternatively spliced transcript variants encoding multiple isoforms have been observed for this gene. [provided by RefSeq, Dec 2011]

ACMG classification

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 9.483568 fraction of the gene.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 19-29702978-CT-C is Pathogenic according to our data. Variant chr19-29702978-CT-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 434550.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
C19orf12	NM_031448.6	c.161-2del		splice_acceptor_variant		ENST00000323670.14

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
C19orf12	ENST00000323670.14	c.161-2del		splice_acceptor_variant		2	NM_031448.6	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000803 AC: 2 AN: 249052 Hom.: 0 AF XY: 0.00000742 AC XY: 1 AN XY: 134820

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

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: 0.000163

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461856 Hom.: 0 Cov.: 36 AF XY: 0.00000275 AC XY: 2 AN XY: 727230

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Neurodegeneration with brain iron accumulation 4 Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	3billion	Sep 01, 2022	The variant is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: <0.001%). Canonical splice site is predicted to alter splicing and result in a loss or disruption of normal protein function. The predicted truncated protein may be shortened by more than 10%. Multiple pathogenic variants are reported downstream of the variant. The variant has been reported to be associated with C19orf12-related disorder (ClinVar ID: VCV000434550 / PMID: 29915382). Therefore, this variant is classified as Likely pathogenic according to the recommendation of ACMG/AMP guideline. -
Pathogenic, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Aug 26, 2016	- -

Hereditary spastic paraplegia 43 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 27, 2022

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: 434550). This variant has been observed in individuals with clinical features of autosomal recessive neurodegeneration with brain iron accumulation (PMID: 23269600, 29915382). This variant is present in population databases (no rsID available, gnomAD 0.003%). This sequence change falls in intron 2 of the C19orf12 gene. It does not directly change the encoded amino acid sequence of the C19orf12 protein. It affects a nucleotide within the consensus splice site. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.84		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.64		Position offset: -25
DS_AL_spliceai		0.84		Position offset: -1

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

Publications

LitVar

Other links and lift over

dbSNP: rs1352744778; hg19: chr19-30193885;