4-3223644-A-T

Variant names:

• chr4-3223644-A-T
• rs82334
• NM_001388492.1:c.7625+84A>T

Variant summary

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

The NM_001388492.1(HTT):​c.7625+84A>T variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: HTT NM_001388492.1 intron
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -0.666
• Publications: 18 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: 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 (BayesDel_noAF=-0.87).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HTT	NM_001388492.1	c.7625+84A>T		intron_variant	Intron 55 of 66	ENST00000355072.11	NP_001375421.1
HTT	NM_002111.8	c.7625+84A>T		intron_variant	Intron 55 of 66		NP_002102.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HTT	ENST00000355072.11	c.7625+84A>T		intron_variant	Intron 55 of 66	1	NM_001388492.1	ENSP00000347184.5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Data not reliable, filtered out with message: AC0;AS_VQSR AF: 0.00 AC: 0 AN: 1098066 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 547580

African (AFR) AF: 0.00 AC: 0 AN: 25252

American (AMR) AF: 0.00 AC: 0 AN: 27484

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 18330

East Asian (EAS) AF: 0.00 AC: 0 AN: 37296

South Asian (SAS) AF: 0.00 AC: 0 AN: 63774

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 49282

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 4742

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 824710

Other (OTH) AF: 0.00 AC: 0 AN: 47196

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.87
CADD	Benign	1.9
DANN	Benign	0.31
PhyloP100		-0.67

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: rs82334; hg19: chr4-3225371;