6-135466163-G-T

Position:

• chr6-135466163-G-T

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_001134831.2(AHI1):​c.400C>A​(p.Pro134Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,626 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: AHI1 NM_001134831.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.137

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 Likely_benign. Variant got -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.038526416).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
AHI1	NM_001134831.2	c.400C>A	p.Pro134Thr	missense_variant	7/29	ENST00000265602.11	NP_001128303.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
AHI1	ENST00000265602.11	c.400C>A	p.Pro134Thr	missense_variant	7/29	1	NM_001134831.2	ENSP00000265602.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461626 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727088

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Familial aplasia of the vermis Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 15, 2019

Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site, but this prediction has not been confirmed by published transcriptional studies. 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. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with AHI1-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces proline with threonine at codon 134 of the AHI1 protein (p.Pro134Thr). The proline residue is weakly conserved and there is a small physicochemical difference between proline and threonine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.068
BayesDel_addAF	Benign	-0.26	T
BayesDel_noAF	Benign	-0.61
CADD	Benign	0.17
DANN	Benign	0.046
DEOGEN2	Benign	0.096	T;T;T;.;T
Eigen	Benign	-1.2
Eigen_PC	Benign	-1.3
FATHMM_MKL	Benign	0.076	N
LIST_S2	Benign	0.69	.;.;T;T;T
M_CAP	Benign	0.0035	T
MetaRNN	Benign	0.039	T;T;T;T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	0.69	N;N;N;N;.
PrimateAI	Benign	0.23	T
PROVEAN	Benign	0.35	N;N;N;N;N
REVEL	Benign	0.0090
Sift	Benign	1.0	T;T;T;T;T
Sift4G	Benign	0.13	T;T;T;T;.
Polyphen		0.035	B;B;B;B;.
Vest4		0.11
MutPred		0.15		Gain of sheet (P = 0.0149);Gain of sheet (P = 0.0149);Gain of sheet (P = 0.0149);Gain of sheet (P = 0.0149);.;
MVP		0.18
MPC		0.048
ClinPred		0.029	T
GERP RS		-0.56
Varity_R		0.018
gMVP		0.044

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

Publications

LitVar

Other links and lift over

dbSNP: rs368077581; hg19: chr6-135787301;