12-111598978-TTGCTGCTGCTGCTGCTGCTGCTGCTGC-TTGCTGCTGCTGCTGCTGCTGCTGCTGCTGCTGCTGCTGC

Variant names:

• chr12-111598978-T-TTGCTGCTGCTGC
• rs193922927
• NM_001372574.1:c.45_56dupGCAGCAGCAGCA

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 0P and 1B. BP3

The NM_001372574.1(ATXN2):​c.45_56dupGCAGCAGCAGCA​(p.Gln16_Gln19dup) variant causes a disruptive inframe insertion change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000727 in 137,578 control chromosomes in the GnomAD database, with no homozygous occurrence. It is difficult to determine the true allele frequency of this variant because it is of type INS_BIG, and the frequency of such variant types in population databases may be underestimated and unreliable. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. Q19Q) has been classified as Benign.

• Frequency:
  • Genomes: 𝑓 0.0000073 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000026 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: ATXN2 NM_001372574.1 disruptive_inframe_insertion
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.273
• Publications: 2 publications found

Genes affected

ATXN2 (HGNC:10555): (ataxin 2) This gene belongs to a group of genes that is associated with microsatellite-expansion diseases, a class of neurological and neuromuscular disorders caused by expansion of short stretches of repetitive DNA. The protein encoded by this gene has two globular domains near the N-terminus, one of which contains a clathrin-mediated trans-Golgi signal and an endoplasmic reticulum exit signal. The encoded cytoplasmic protein localizes to the endoplasmic reticulum and plasma membrane, is involved in endocytosis, and modulates mTOR signals, modifying ribosomal translation and mitochondrial function. The N-terminal region of the protein contains a polyglutamine tract of 14-31 residues that can be expanded in the pathogenic state to 32-200 residues. Intermediate length expansions of this tract increase susceptibility to amyotrophic lateral sclerosis, while long expansions of this tract result in spinocerebellar ataxia-2, an autosomal-dominantly inherited, neurodegenerative disorder. Genome-wide association studies indicate that loss-of-function mutations in this gene may be associated with susceptibility to type I diabetes, obesity and hypertension. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Nov 2016]

ATXN2-AS (HGNC:51838): (ATXN2 antisense RNA)

ACMG classification

Our verdict: Likely_benign. The variant received -1 ACMG points.

• BP3: Nonframeshift variant in repetitive region in NM_001372574.1

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ATXN2	NM_001372574.1	c.45_56dupGCAGCAGCAGCA	p.Gln16_Gln19dup	disruptive_inframe_insertion	Exon 1 of 25	ENST00000673436.1	NP_001359503.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ATXN2	ENST00000673436.1	c.45_56dupGCAGCAGCAGCA	p.Gln16_Gln19dup	disruptive_inframe_insertion	Exon 1 of 25		NM_001372574.1	ENSP00000500925.1

Frequencies

GnomAD3 genomes AF: 0.00000727 AC: 1 AN: 137578 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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: 0.0000160

Gnomad OTH AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.00000260 AC: 3 AN: 1155338 Hom.: 0 Cov.: 74 AF XY: 0.00 AC XY: 0 AN XY: 568204

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 24914

American (AMR) AF: 0.00 AC: 0 AN: 27174

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 22082

East Asian (EAS) AF: 0.00 AC: 0 AN: 26042

South Asian (SAS) AF: 0.00 AC: 0 AN: 59218

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 32120

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 3382

European-Non Finnish (NFE) AF: 0.00000219 AC: 2 AN: 912380

Other (OTH) AF: 0.0000208 AC: 1 AN: 48026

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.0183214), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome AF: 0.00000727 AC: 1 AN: 137578 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 66910

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 37744

American (AMR) AF: 0.00 AC: 0 AN: 13900

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3214

East Asian (EAS) AF: 0.00 AC: 0 AN: 4356

South Asian (SAS) AF: 0.00 AC: 0 AN: 4338

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 8574

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 284

European-Non Finnish (NFE) AF: 0.0000160 AC: 1 AN: 62456

Other (OTH) AF: 0.00 AC: 0 AN: 1864

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		0.27
Mutation Taster		=85/15	polymorphism

Splicing

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

Other links and lift over

dbSNP: rs193922927; hg19: chr12-112036782;