4-3146897-G-A

Variant names:

• chr4-3146897-G-A
• rs1065746
• NM_001388492.1:c.3244G>A

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_001388492.1(HTT):​c.3244G>A​(p.Asp1082Asn) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. D1082H) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: HTT NM_001388492.1 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 9.70
• Publications: 6 publications found

Genes affected

HTT (HGNC:4851): (huntingtin) Huntingtin is a disease gene linked to Huntington's disease, a neurodegenerative disorder characterized by loss of striatal neurons. This is thought to be caused by an expanded, unstable trinucleotide repeat in the huntingtin gene, which translates as a polyglutamine repeat in the protein product. A fairly broad range of trinucleotide repeats (9-35) has been identified in normal controls, and repeat numbers in excess of 40 have been described as pathological. The huntingtin locus is large, spanning 180 kb and consisting of 67 exons. The huntingtin gene is widely expressed and is required for normal development. It is expressed as 2 alternatively polyadenylated forms displaying different relative abundance in various fetal and adult tissues. The larger transcript is approximately 13.7 kb and is expressed predominantly in adult and fetal brain whereas the smaller transcript of approximately 10.3 kb is more widely expressed. The genetic defect leading to Huntington's disease may not necessarily eliminate transcription, but may confer a new property on the mRNA or alter the function of the protein. One candidate is the huntingtin-associated protein-1, highly expressed in brain, which has increased affinity for huntingtin protein with expanded polyglutamine repeats. This gene contains an upstream open reading frame in the 5' UTR that inhibits expression of the huntingtin gene product through translational repression. [provided by RefSeq, Jul 2016]

HTT Gene-Disease associations (from GenCC):

• Huntington disease

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Ambry Genetics, ClinGen, Labcorp Genetics (formerly Invitae), Orphanet
• Lopes-Maciel-Rodan syndrome

  Inheritance: AR Classification: STRONG, LIMITED Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• juvenile Huntington disease

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.905

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001388492.1. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HTT	NM_001388492.1	MANE Select	c.3244G>A	p.Asp1082Asn	missense	Exon 25 of 67	NP_001375421.1
	HTT	NM_002111.8		c.3244G>A	p.Asp1082Asn	missense	Exon 25 of 67	NP_002102.4

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HTT	ENST00000355072.11	TSL:1 MANE Select	c.3244G>A	p.Asp1082Asn	missense	Exon 25 of 67	ENSP00000347184.5
	HTT	ENST00000510626.5	TSL:1	n.3343G>A		non_coding_transcript_exon	Exon 12 of 53
	HTT	ENST00000681528.1		c.2986G>A	p.Asp996Asn	missense	Exon 25 of 68	ENSP00000506116.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.70
BayesDel_addAF	Uncertain	0.034	T
BayesDel_noAF	Benign	-0.19
CADD	Pathogenic	27
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.59	D
Eigen	Pathogenic	0.73
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D
M_CAP	Uncertain	0.21	D
MetaRNN	Pathogenic	0.91	D
MetaSVM	Uncertain	0.024	D
MutationAssessor	Uncertain	2.3	M
PhyloP100		9.7
PrimateAI	Uncertain	0.76	T
PROVEAN	Pathogenic	-4.7	D
REVEL	Uncertain	0.54
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.98
MutPred		0.64		Gain of relative solvent accessibility (P = 0.0215)
MVP		0.82
MPC		1.1
ClinPred		0.99	D
GERP RS		4.7
Varity_R		0.88
gMVP		0.83
Mutation Taster		=61/39	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: rs1065746; hg19: chr4-3148624;