6-135433125-C-T

Variant names:

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1PM5PP3_StrongPP5

The NM_001134831.2(AHI1):c.2168G>A(p.Arg723Gln) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000806 in 1,613,060 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R723W) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000062 ( 0 hom. )

Consequence

AHI1
NM_001134831.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:8U:2

Conservation

PhyloP100: 7.38

Publications

13 publications found

Variant links:

Genes affected

AHI1 (HGNC:21575): (Abelson helper integration site 1) This gene is apparently required for both cerebellar and cortical development in humans. This gene mutations cause specific forms of Joubert syndrome-related disorders. Joubert syndrome (JS) is a recessively inherited developmental brain disorder with several identified causative chromosomal loci. Alternatively spliced transcript variants encoding different isoforms have been identified. [provided by RefSeq, Oct 2008]

AHI1 Gene-Disease associations (from GenCC):

Joubert syndrome 3
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, ClinGen, Laboratory for Molecular Medicine, Ambry Genetics
Joubert syndrome
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
Joubert syndrome with ocular defect
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
retinitis pigmentosa
Inheritance: AR, AD Classification: SUPPORTIVE, LIMITED Submitted by: Ambry Genetics, Orphanet

AHI1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

PM1

In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 2 uncertain in NM_001134831.2

PM5

Other missense variant is known to change same aminoacid residue: Variant chr6-135433126-G-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2739522.Status of the report is criteria_provided_single_submitter, 1 stars.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.984

PP5

Variant 6-135433125-C-T is Pathogenic according to our data. Variant chr6-135433125-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 2015.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
AHI1	NM_001134831.2 link	c.2168G>A	p.Arg723Gln	missense_variant	Exon 16 of 29	ENST00000265602.11	NP_001128303.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
AHI1	ENST00000265602.11 link	c.2168G>A	p.Arg723Gln	missense_variant	Exon 16 of 29	1	NM_001134831.2	ENSP00000265602.6

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

152130

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000196

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000281

AC:

AN:

248918

AF XY:

0.0000222

show subpopulations

Gnomad AFR exome

AF:

0.0000646

Gnomad AMR exome

AF:

0.0000579

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000355

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000616

AC:

AN:

1460930

Hom.:

Cov.:

AF XY:

0.00000550

AC XY:

AN XY:

726818

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33458

American (AMR)

AF:

0.0000447

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26124

East Asian (EAS)

AF:

0.00

AC:

AN:

39620

South Asian (SAS)

AF:

0.00

AC:

AN:

86248

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53396

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5764

European-Non Finnish (NFE)

AF:

0.00000450

AC:

AN:

1111256

Other (OTH)

AF:

0.0000166

AC:

AN:

60344

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.469

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:

0.0000263

AC:

AN:

152130

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74308

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41438

American (AMR)

AF:

0.000196

AC:

AN:

15274

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5200

South Asian (SAS)

AF:

0.00

AC:

AN:

4822

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10602

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68004

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.575

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.0000197

Hom.:

Bravo

AF:

0.0000567

ExAC

AF:

0.0000414

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:8Uncertain:2

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Joubert syndrome 3

Pathogenic:4Uncertain:2

Feb 23, 2015

UW Hindbrain Malformation Research Program, University of Washington

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:research

- -

Mar 01, 2006

OMIM

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:literature only

- -

May 31, 2018

SIB Swiss Institute of Bioinformatics

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:curation

This variant is interpreted as a Likely Pathogenic, for Joubert syndrome, in Autosomal Recessive manner. The following ACMG Tag(s) were applied: PP3 => Multiple lines of computational evidence support a deleterious effect on the gene or gene product. PM2 => Absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium. PS3 => Well-established functional studies show a deleterious effect (PMID:21623382). -

May 04, 2022

Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:curation

The homozygous p.Arg723Gln variant in AHI1 was identified by our study in 2 siblings with Joubert syndrome 3. The variant has been reported in 4 individuals of Italian and unknown ethnicity with Joubert syndrome 3 (PMID: 26092869, 31202121, 16453322, 26354092), and has been identified in 0.008% (3/35370) of Latino, 0.008% (2/24202) of African, and 0.003% (4/128110) of European non-Finnish chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP ID: rs121434351). Although this variant has been seen in the general population, its frequency is low enough to be consistent with a recessive carrier frequency. This variant has also been reported in ClinVar (Variation ID: 2015) as pathogenic by OMIM and UW Hindbrain Malformation Research Program, University of Washington, and as likely pathogenic by Invitae and SIB Swiss Institute of Bioinformatics. In vitro functional studies provide some evidence that the p.Arg723Gln variant may slightly impact protein function (PMID: 21623382). However, these types of assays may not accurately represent biological function. Computational prediction tools and conservation analyses do not provide strong support for or against an impact to the protein. The presence of this variant in at least 2 affected homozygotes and in 2 individuals with Joubert syndrome 3 increases the likelihood that the p.Arg723Gln variant is pathogenic (PMID: 26092869, 31202121, 16453322). In summary, while there is some suspicion for a pathogenic role, the clinical significance of this variant is uncertain. ACMG/AMP Criteria applied: PM2, PM3, PS3_supporting (Richards 2015). -

Apr 04, 2024

Fulgent Genetics, Fulgent Genetics

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Neurology Department of Pediatrics, The Third Affiliated Hospital of Zhengzhou University

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Joubert syndrome

Pathogenic:1

Jan 06, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces arginine, which is basic and polar, with glutamine, which is neutral and polar, at codon 723 of the AHI1 protein (p.Arg723Gln). This variant is present in population databases (rs121434351, gnomAD 0.009%). This missense change has been observed in individual(s) with Joubert syndrome (PMID: 16453322, 26092869; internal data). ClinVar contains an entry for this variant (Variation ID: 2015). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt AHI1 protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects AHI1 function (PMID: 21623382). For these reasons, this variant has been classified as Pathogenic. -

not provided

Pathogenic:1

Aug 01, 2023

GeneDx

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Published functional studies demonstrate R723Q fails to localize to the primary cilium compared to the wild-type protein (Lancaster et al., 2011); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Not observed at a significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 26354092, 16453322, 26092869, 31202121, 25217387, 31589614, 34448047, 15467982, 28442542, 34220074, 31069529, 21623382) -

AHI1-related disorder

Pathogenic:1

Sep 27, 2024

PreventionGenetics, part of Exact Sciences

Significance:Likely pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

The AHI1 c.2168G>A variant is predicted to result in the amino acid substitution p.Arg723Gln. This variant has been reported in both the homozygous and compound heterozygous state in individuals with Joubert syndrome (Valente et al. 2006. PubMed ID: 16453322; Ganapathy et al. 2019. PubMed ID: 31069529; Perea-Romero et al. 2021. PubMed ID: 34448047; Bachmann-Gagescu et al. 2015. PubMed ID: 26092869; Altieri et al. 2019. PubMed ID: 31202121; Sharawat et al. 2021. PubMed ID: 34220074). This variant is reported in 0.0085% of alleles in individuals of Latino descent in gnomAD. Functional studies indicate that the c.2168G>A (p.Arf723Gln) variant showed similar protein expression to wildtype protein in 293T cells and mouse inner medullary collecting duct cells, but failure to localize to the primary cilium compared to wildtype (Lancaster et al. 2011. PubMed ID: 21623382). This variant is interpreted as likely pathogenic. -

Joubert syndrome with ocular defect

Pathogenic:1

Laboratory of Genetics in Ophthalmology, Institut Imagine

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:research

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.65

BayesDel_addAF

Pathogenic

0.23

BayesDel_noAF

Pathogenic

0.27

CADD

Pathogenic

(source)

DANN

Pathogenic

1.0

DEOGEN2

Uncertain

0.52

D;D;D;.

Eigen

Pathogenic

0.94

Eigen_PC

Pathogenic

0.90

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.96

.;.;D;D

M_CAP

Benign

0.044

MetaRNN

Pathogenic

0.98

D;D;D;D

MetaSVM

Uncertain

0.18

MutationAssessor

Pathogenic

3.7

H;H;H;H

PhyloP100

7.4

PrimateAI

Benign

0.48

PROVEAN

Uncertain

-3.4

D;D;D;D

REVEL

Pathogenic

0.67

Sift

Benign

0.037

D;D;D;D

Sift4G

Pathogenic

0.0

D;D;D;D

Polyphen

1.0

D;D;D;D

Vest4

0.98

MutPred

0.89

Gain of methylation at K726 (P = 0.0517);Gain of methylation at K726 (P = 0.0517);Gain of methylation at K726 (P = 0.0517);Gain of methylation at K726 (P = 0.0517);

MVP

0.89

MPC

0.31

ClinPred

0.96

GERP RS

5.7

Varity_R

0.53

gMVP

0.77

Mutation Taster

=1/99

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.11

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

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over