9-27546688-C-T

Variant summary

Our verdict is Benign. Variant got -8 ACMG points: 0P and 8B. BP4_Strong BS2

The NM_018325.5(C9orf72):c.*1548G>A variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000854 in 152,232 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: 𝑓 0.000085 (0 hom., cov: 33)
• Consequence: C9orf72 NM_018325.5 3_prime_UTR
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.498

Genes affected

C9orf72 (HGNC:28337): (C9orf72-SMCR8 complex subunit) The protein encoded by this gene plays an important role in the regulation of endosomal trafficking, and has been shown to interact with Rab proteins that are involved in autophagy and endocytic transport. Expansion of a GGGGCC repeat from 2-22 copies to 700-1600 copies in the intronic sequence between alternate 5' exons in transcripts from this gene is associated with 9p-linked ALS (amyotrophic lateral sclerosis) and FTD (frontotemporal dementia) (PMID: 21944778, 21944779). Studies suggest that hexanucleotide expansions could result in the selective stabilization of repeat-containing pre-mRNA, and the accumulation of insoluble dipeptide repeat protein aggregates that could be pathogenic in FTD-ALS patients (PMID: 23393093). Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Jul 2016]

ACMG classification

Verdict is Benign. Variant got -8 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.75).
• BS2: High AC in GnomAd at 13 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
C9orf72	NM_018325.5	c.*1548G>A		3_prime_UTR_variant	11/11	ENST00000380003.8
C9orf72	NM_001256054.3	c.*1548G>A		3_prime_UTR_variant	11/11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
C9orf72	ENST00000380003.8	c.*1548G>A		3_prime_UTR_variant	11/11	1	NM_018325.5	P1
C9orf72	ENST00000619707.5	c.*1548G>A		3_prime_UTR_variant	11/11	1		P1
C9orf72	ENST00000488117.5	n.4675G>A		non_coding_transcript_exon_variant	10/10	2
C9orf72	ENST00000673600.1	c.*267+1427G>A		intron_variant, NMD_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.0000855 AC: 13 AN: 152114 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000656

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000147

Gnomad OTH AF: 0.000478

GnomAD4 exome Cov.: 0

GnomAD4 genome AF: 0.0000854 AC: 13 AN: 152232 Hom.: 0 Cov.: 33 AF XY: 0.0000672 AC XY: 5 AN XY: 74432

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.0000655

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000147

Gnomad4 OTH AF: 0.000473

Alfa AF: 0.000214 Hom.: 0

Bravo AF: 0.000110

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Frontotemporal dementia and/or amyotrophic lateral sclerosis 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.75
Cadd	Benign	5.7
Dann	Benign	0.74

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: rs549660498; hg19: chr9-27546686;