chr6-16326440-G-T

Variant names:

• chr6-16326440-G-T
• rs539283031
• NM_001128164.2:c.1871C>A

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_001128164.2(ATXN1):​c.1871C>A​(p.Pro624Gln) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,784 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. P624L) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: ATXN1 NM_001128164.2 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 5.24
• 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: Uncertain_significance. The variant received 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ATXN1	NM_001128164.2	c.1871C>A	p.Pro624Gln	missense_variant	Exon 7 of 8	ENST00000436367.6	NP_001121636.1
ATXN1	NM_000332.4	c.1871C>A	p.Pro624Gln	missense_variant	Exon 8 of 9		NP_000323.2
ATXN1	NM_001357857.2	c.*1284C>A		3_prime_UTR_variant	Exon 8 of 9		NP_001344786.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ATXN1	ENST00000436367.6	c.1871C>A	p.Pro624Gln	missense_variant	Exon 7 of 8	1	NM_001128164.2	ENSP00000416360.1
ATXN1	ENST00000244769.8	c.1871C>A	p.Pro624Gln	missense_variant	Exon 8 of 9	1		ENSP00000244769.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461784 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 727192

⚠️ 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: 33474

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

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

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53388

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

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111950

Other (OTH) AF: 0.00 AC: 0 AN: 60392

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.10
BayesDel_addAF	Uncertain	0.078	D
BayesDel_noAF	Benign	-0.13
CADD	Benign	23
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.74	D;D
Eigen	Uncertain	0.52
Eigen_PC	Uncertain	0.46
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.81	.;T
M_CAP	Uncertain	0.17	D
MetaRNN	Uncertain	0.64	D;D
MetaSVM	Uncertain	0.018	D
MutationAssessor	Benign	1.8	L;L
PhyloP100		5.2
PrimateAI	Uncertain	0.49	T
PROVEAN	Uncertain	-2.9	D;D
REVEL	Uncertain	0.58
Sift	Uncertain	0.0040	D;D
Sift4G	Uncertain	0.0090	D;D
Polyphen		0.99	D;D
Vest4		0.32
MutPred		0.68		Loss of sheet (P = 0.0817);Loss of sheet (P = 0.0817);
MVP		0.91
MPC		0.39
ClinPred		0.96	D
GERP RS		4.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.58
gMVP		0.44
Mutation Taster		=53/47	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

dbSNP: rs539283031; hg19: chr6-16326671;