6-16306607-C-T

Variant names:

• chr6-16306607-C-T
• NM_001128164.2:c.2170G>A

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_001128164.2(ATXN1):​c.2170G>A​(p.Ala724Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,888 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: ATXN1 NM_001128164.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.0290
• 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, Orphanet, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.06688145).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ATXN1	NM_001128164.2	c.2170G>A	p.Ala724Thr	missense_variant	Exon 8 of 8	ENST00000436367.6	NP_001121636.1
ATXN1	NM_000332.4	c.2170G>A	p.Ala724Thr	missense_variant	Exon 9 of 9		NP_000323.2
ATXN1	NM_001357857.2	c.*1583G>A		3_prime_UTR_variant	Exon 9 of 9		NP_001344786.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ATXN1	ENST00000436367.6	c.2170G>A	p.Ala724Thr	missense_variant	Exon 8 of 8	1	NM_001128164.2	ENSP00000416360.1
ATXN1	ENST00000244769.8	c.2170G>A	p.Ala724Thr	missense_variant	Exon 9 of 9	1		ENSP00000244769.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461888 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727242

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: 53414

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1112012

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

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Mar 16, 2022

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2170G>A (p.A724T) alteration is located in exon 9 (coding exon 2) of the ATXN1 gene. This alteration results from a G to A substitution at nucleotide position 2170, causing the alanine (A) at amino acid position 724 to be replaced by a threonine (T). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.072
BayesDel_addAF	Benign	-0.12	T
BayesDel_noAF	Benign	-0.40
CADD	Benign	4.4
DANN	Uncertain	0.99
DEOGEN2	Benign	0.29	T;T
Eigen	Benign	-0.52
Eigen_PC	Benign	-0.37
FATHMM_MKL	Benign	0.31	N
LIST_S2	Benign	0.68	.;T
M_CAP	Benign	0.018	T
MetaRNN	Benign	0.067	T;T
MetaSVM	Benign	-0.82	T
MutationAssessor	Benign	0.29	N;N
PhyloP100		0.029
PrimateAI	Benign	0.30	T
PROVEAN	Benign	-0.94	N;N
REVEL	Benign	0.15
Sift	Benign	0.24	T;T
Sift4G	Benign	0.25	T;T
Polyphen		0.029	B;B
Vest4		0.079
MutPred		0.20		Loss of helix (P = 0.0104);Loss of helix (P = 0.0104);
MVP		0.81
MPC		0.40
ClinPred		0.20	T
GERP RS		5.2
Varity_R		0.060
gMVP		0.37
Mutation Taster		=92/8	polymorphism

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

hg19: chr6-16306838;