rs768047421

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PP3_ModerateBS1_Supporting

The NM_001388492.1(HTT):c.2108C>T(p.Pro703Leu) variant causes a missense change. The variant allele was found at a frequency of 0.0000428 in 1,612,578 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.000039 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000043 ( 0 hom. )

Consequence

HTT
NM_001388492.1 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts P:1U:2

Conservation

PhyloP100: 5.70

Publications

3 publications found

Variant links:

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

HTT links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.883

BS1

Variant frequency is greater than expected in population mid. GnomAdExome4 allele frequency = 0.0000431 (63/1460470) while in subpopulation MID AF = 0.000532 (3/5640). AF 95% confidence interval is 0.000144. There are 0 homozygotes in GnomAdExome4. There are 41 alleles in the male GnomAdExome4 subpopulation. Median coverage is 31. This position passed quality control check. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HTT	NM_001388492.1 link	c.2108C>T	p.Pro703Leu	missense_variant	Exon 16 of 67	ENST00000355072.11	NP_001375421.1
HTT	NM_002111.8 link	c.2108C>T	p.Pro703Leu	missense_variant	Exon 16 of 67		NP_002102.4	P42858

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HTT	ENST00000355072.11 link	c.2108C>T	p.Pro703Leu	missense_variant	Exon 16 of 67	1	NM_001388492.1	ENSP00000347184.5		P42858

Frequencies

GnomAD3 genomes

AF:

0.0000394

AC:

AN:

152108

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000242

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.000576

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000441

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000806

AC:

AN:

248284

AF XY:

0.000104

show subpopulations

Gnomad AFR exome

AF:

0.0000647

Gnomad AMR exome

AF:

0.0000293

Gnomad ASJ exome

AF:

0.000701

Gnomad EAS exome

AF:

0.0000558

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000266

Gnomad OTH exome

AF:

0.000166

GnomAD4 exome

AF:

0.0000431

AC:

AN:

1460470

Hom.:

Cov.:

AF XY:

0.0000564

AC XY:

AN XY:

726420

show subpopulations

African (AFR)

AF:

0.0000599

AC:

AN:

33412

American (AMR)

AF:

0.0000225

AC:

AN:

44436

Ashkenazi Jewish (ASJ)

AF:

0.000921

AC:

AN:

26066

East Asian (EAS)

AF:

0.0000252

AC:

AN:

39666

South Asian (SAS)

AF:

0.000162

AC:

AN:

86166

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53404

Middle Eastern (MID)

AF:

0.000532

AC:

AN:

5640

European-Non Finnish (NFE)

AF:

0.0000117

AC:

AN:

1111358

Other (OTH)

AF:

0.0000829

AC:

AN:

60322

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.505

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000394

AC:

AN:

152108

Hom.:

Cov.:

AF XY:

0.0000404

AC XY:

AN XY:

74294

show subpopulations

African (AFR)

AF:

0.0000242

AC:

AN:

41404

American (AMR)

AF:

0.00

AC:

AN:

15268

Ashkenazi Jewish (ASJ)

AF:

0.000576

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5186

South Asian (SAS)

AF:

0.00

AC:

AN:

4822

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10610

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000441

AC:

AN:

68026

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.508

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.000115

Hom.:

Bravo

AF:

0.0000756

TwinsUK

AF:

0.000270

AC:

ALSPAC

AF:

0.00

AC:

ExAC

AF:

0.0000495

AC:

EpiCase

AF:

0.000109

EpiControl

AF:

0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Lopes-Maciel-Rodan syndrome

Pathogenic:1

Apr 15, 2017

OMIM

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:literature only

- -

Huntington disease

Uncertain:1

Sep 22, 2024

Genomic Medicine Center of Excellence, King Faisal Specialist Hospital and Research Centre

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not provided

Uncertain:1

Oct 14, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. ClinVar contains an entry for this variant (Variation ID: 417742). This missense change has been observed in individual(s) with clinical features of Rett syndrome (PMID: 26740508). This variant is present in population databases (rs768047421, gnomAD 0.07%). This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 705 of the HTT protein (p.Pro705Leu). -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.30

BayesDel_addAF

Uncertain

0.13

BayesDel_noAF

Pathogenic

0.23

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Uncertain

0.62

Eigen

Uncertain

0.54

Eigen_PC

Uncertain

0.50

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.88

M_CAP

Uncertain

0.26

MetaRNN

Pathogenic

0.88

MetaSVM

Uncertain

-0.060

MutationAssessor

Pathogenic

3.0

PhyloP100

5.7

PrimateAI

Uncertain

0.66

PROVEAN

Pathogenic

-6.2

REVEL

Pathogenic

0.66

Sift

Uncertain

0.0030

Sift4G

Uncertain

0.0060

Polyphen

1.0

Vest4

0.94

MVP

0.92

MPC

0.38

ClinPred

0.92

GERP RS

4.8

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

Varity_R

0.49

gMVP

0.56

Mutation Taster

=75/25

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.060

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over