chr6-135455872-AG-A

Position:

• chr6-135455872-AG-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_001134831.2(AHI1):​c.1205delC​(p.Pro402fs) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000209 in 1,433,836 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: AHI1 NM_001134831.2 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 9.60

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 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 6-135455872-AG-A is Pathogenic according to our data. Variant chr6-135455872-AG-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 202167.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr6-135455872-AG-A is described in Lovd as [Pathogenic]. Variant chr6-135455872-AG-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
AHI1	NM_001134831.2	c.1205delC	p.Pro402fs	frameshift_variant	10/29	ENST00000265602.11	NP_001128303.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
AHI1	ENST00000265602.11	c.1205delC	p.Pro402fs	frameshift_variant	10/29	1	NM_001134831.2	ENSP00000265602.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000209 AC: 3 AN: 1433836 Hom.: 0 Cov.: 30 AF XY: 0.00000141 AC XY: 1 AN XY: 709826

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000233

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000122

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000169

GnomAD4 genome Cov.: 32

Bravo AF: 0.0000113

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

May 31, 2024

Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 32865313, 29186038) -

Joubert syndrome 1 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Mendelics

May 28, 2019

- -

Familial aplasia of the vermis Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 14, 2023

This sequence change creates a premature translational stop signal (p.Pro402Leufs*3) in the AHI1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in AHI1 are known to be pathogenic (PMID: 15322546, 16453322, 28442542, 29186038). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with clinical features of Joubert syndrome (PMID: 29186038). ClinVar contains an entry for this variant (Variation ID: 202167). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs794729195; hg19: chr6-135777010;