NM_001134831.2:c.1803C>T

Variant names:

• chr6-135442691-G-A
• rs375537062
• NM_001134831.2:c.1803C>T

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2 BP4_Strong BP7

The NM_001134831.2(AHI1):​c.1803C>T​(p.His601His) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000686 in 1,458,612 control chromosomes in the GnomAD database, with no homozygous occurrence. 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: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: AHI1 NM_001134831.2 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.708
• Publications: 0 publications found

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

ACMG classification

Our verdict: Likely_benign. The variant received -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (REVEL=0.008).
• BP7: Synonymous conserved (PhyloP=0.708 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
AHI1	NM_001134831.2	c.1803C>T	p.His601His	synonymous_variant	Exon 14 of 29	ENST00000265602.11	NP_001128303.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
AHI1	ENST00000265602.11	c.1803C>T	p.His601His	synonymous_variant	Exon 14 of 29	1	NM_001134831.2	ENSP00000265602.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.86e-7 AC: 1 AN: 1458612 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 725490

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33400

American (AMR) AF: 0.00 AC: 0 AN: 44442

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25950

East Asian (EAS) AF: 0.00 AC: 0 AN: 39616

South Asian (SAS) AF: 0.0000117 AC: 1 AN: 85684

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53212

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5716

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1110390

Other (OTH) AF: 0.00 AC: 0 AN: 60202

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.48
CADD	Benign	8.8
DANN	Benign	0.60
PhyloP100		0.71
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

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

Other links and lift over

dbSNP: rs375537062; hg19: chr6-135763829;