6-16326507-C-T

Variant names:

• chr6-16326507-C-T
• rs1760808820
• NM_001128164.2:c.1804G>A

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_001128164.2(ATXN1):​c.1804G>A​(p.Ala602Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,892 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A602S) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: ATXN1 NM_001128164.2 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.46
• Publications: 0 publications found

Genes affected

ATXN1 (HGNC:10548): (ataxin 1) The autosomal dominant cerebellar ataxias (ADCA) are a heterogeneous group of neurodegenerative disorders characterized by progressive degeneration of the cerebellum, brain stem and spinal cord. Clinically, ADCA has been divided into three groups: ADCA types I-III. ADCAI is genetically heterogeneous, with five genetic loci, designated spinocerebellar ataxia (SCA) 1, 2, 3, 4 and 6, being assigned to five different chromosomes. ADCAII, which always presents with retinal degeneration (SCA7), and ADCAIII often referred to as the `pure' cerebellar syndrome (SCA5), are most likely homogeneous disorders. Several SCA genes have been cloned and shown to contain CAG repeats in their coding regions. ADCA is caused by the expansion of the CAG repeats, producing an elongated polyglutamine tract in the corresponding protein. The expanded repeats are variable in size and unstable, usually increasing in size when transmitted to successive generations. The function of the ataxins is not known. This locus has been mapped to chromosome 6, and it has been determined that the diseased allele contains 40-83 CAG repeats, compared to 6-39 in the normal allele, and is associated with spinocerebellar ataxia type 1 (SCA1). Alternative splicing results in multiple transcript variants, with one variant encoding multiple distinct proteins, ATXN1 and Alt-ATXN1, due to the use of overlapping alternate reading frames. [provided by RefSeq, Nov 2017]

ATXN1 Gene-Disease associations (from GenCC):

• spinocerebellar ataxia type 1

  Inheritance: AD Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.957

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001128164.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ATXN1	NM_001128164.2	MANE Select	c.1804G>A	p.Ala602Thr	missense	Exon 7 of 8	NP_001121636.1	P54253-1
	ATXN1	NM_000332.4		c.1804G>A	p.Ala602Thr	missense	Exon 8 of 9	NP_000323.2	P54253-1
	ATXN1	NM_001357857.2		c.*1217G>A		3_prime_UTR	Exon 8 of 9	NP_001344786.1	A0A2R8YCF3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ATXN1	ENST00000436367.6	TSL:1 MANE Select	c.1804G>A	p.Ala602Thr	missense	Exon 7 of 8	ENSP00000416360.1	P54253-1
	ATXN1	ENST00000244769.8	TSL:1	c.1804G>A	p.Ala602Thr	missense	Exon 8 of 9	ENSP00000244769.3	P54253-1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461892 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 727248

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1112012

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.97
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.29
CADD	Uncertain	23
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.83	D
Eigen	Uncertain	0.23
Eigen_PC	Uncertain	0.25
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.92	D
M_CAP	Uncertain	0.21	D
MetaRNN	Pathogenic	0.96	D
MetaSVM	Uncertain	-0.21	T
MutationAssessor	Benign	1.6	L
PhyloP100		7.5
PrimateAI	Uncertain	0.77	T
PROVEAN	Uncertain	-3.6	D
REVEL	Pathogenic	0.78
Sift	Uncertain	0.012	D
Sift4G	Benign	0.090	T
Polyphen		0.81	P
Vest4		0.92
MutPred		0.80		Loss of helix (P = 0.079)
MVP		0.93
MPC		1.0
ClinPred		0.97	D
GERP RS		4.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.53
gMVP		0.53
Mutation Taster		=29/71	disease causing

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

Other links and lift over

dbSNP: rs1760808820; hg19: chr6-16326738;