Genetic Variant ATXN3:p.Gln305_Gly306insGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGln (chr14-92071010-C-CCTGCTGCTGCTGCTGCTGCTGCTGCTGCTGCTGTTGCTGCTG) – ACMG Classification: Likely_benign (-1 pts)

Variant summary

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

The NM_004993.6(ATXN3):c.915_916insCAGCAGCAACAGCAGCAGCAGCAGCAGCAGCAGCAGCAGCAG(p.Gln305_Gly306insGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGln) variant causes a conservative inframe insertion change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000702 in 142,396 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.

Frequency

Genomes: 𝑓 0.0000070 ( 0 hom., cov: 20)

Consequence

ATXN3
NM_004993.6 conservative_inframe_insertion

Scores

Not classified

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: -0.168

Publications

1 publications found

Variant links:

Genes affected

ATXN3 (HGNC:7106): (ataxin 3) Machado-Joseph disease, also known as spinocerebellar ataxia-3, is an autosomal dominant neurologic disorder. The protein encoded by this gene contains (CAG)n repeats in the coding region, and the expansion of these repeats from the normal 12-44 to 52-86 is one cause of Machado-Joseph disease. There is a negative correlation between the age of onset and CAG repeat numbers. Alternatively spliced transcript variants encoding different isoforms have been described for this gene. [provided by RefSeq, Jul 2016]

ATXN3 Gene-Disease associations (from GenCC):

Machado-Joseph disease
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae)
Machado-Joseph disease type 1
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Machado-Joseph disease type 2
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Machado-Joseph disease type 3
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ATXN3 links:

ENSG00000303901 (HGNC:):

ENSG00000303901 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

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

BP3

Nonframeshift variant in repetitive region in NM_004993.6

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ATXN3	NM_004993.6 link	c.915_916insCAGCAGCAACAGCAGCAGCAGCAGCAGCAGCAGCAGCAGCAG	p.Gln305_Gly306insGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGln	conservative_inframe_insertion	Exon 10 of 11	ENST00000644486.2	NP_004984.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ATXN3	ENST00000644486.2 link	c.915_916insCAGCAGCAACAGCAGCAGCAGCAGCAGCAGCAGCAGCAGCAG	p.Gln305_Gly306insGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGlnGln	conservative_inframe_insertion	Exon 10 of 11		NM_004993.6	ENSP00000496695.1

Frequencies

GnomAD3 genomes

AF:

0.00000702

AC:

AN:

142396

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000276

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD4 exome

Cov.:

GnomAD4 genome

AF:

0.00000702

AC:

AN:

142396

Hom.:

Cov.:

AF XY:

0.0000145

AC XY:

AN XY:

69104

show subpopulations

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

African (AFR)

AF:

0.0000276

AC:

AN:

36200

American (AMR)

AF:

0.00

AC:

AN:

14398

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3412

East Asian (EAS)

AF:

0.00

AC:

AN:

4642

South Asian (SAS)

AF:

0.00

AC:

AN:

4314

European-Finnish (FIN)

AF:

0.00

AC:

AN:

9884

Middle Eastern (MID)

AF:

0.00

AC:

AN:

304

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

66422

Other (OTH)

AF:

0.00

AC:

AN:

1940

⚠️ 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.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.325

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

-0.17

Mutation Taster

=78/22

polymorphism

(source)

Splicing

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

Publications

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14-92071010-CCTGCTGCTGCTG-CCTGCTGCTGCTGCTGCTGCTGCTGCTGCTGCTGTTGCTGCTGCTGCTGCTGCTG

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over