2-73490106-CTT-CTTT

Variant names:

• chr2-73490106-C-CT
• rs1553409691
• NM_001378454.1:c.8152dupT

Variant summary

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

The NM_001378454.1(ALMS1):​c.8152dupT​(p.Ser2718PhefsTer7) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: ALMS1 NM_001378454.1 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 0.0580

Genes affected

ALMS1 (HGNC:428): (ALMS1 centrosome and basal body associated protein) This gene encodes a protein containing a large tandem-repeat domain as well as additional low complexity regions. The encoded protein functions in microtubule organization, particularly in the formation and maintanance of cilia. Mutations in this gene cause Alstrom syndrome. There is a pseudogene for this gene located adjacent in the same region of chromosome 2. Alternative splice variants have been described but their full length nature has not been determined. [provided by RefSeq, Apr 2014]

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 2-73490106-C-CT is Pathogenic according to our data. Variant chr2-73490106-C-CT is described in ClinVar as [Likely_pathogenic]. Clinvar id is 557063.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ALMS1	NM_001378454.1	c.8152dupT	p.Ser2718PhefsTer7	frameshift_variant	Exon 10 of 23	ENST00000613296.6	NP_001365383.1
ALMS1	NM_015120.4	c.8152dupT	p.Ser2718PhefsTer7	frameshift_variant	Exon 10 of 23		NP_055935.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ALMS1	ENST00000613296.6	c.8152dupT	p.Ser2718PhefsTer7	frameshift_variant	Exon 10 of 23	1	NM_001378454.1	ENSP00000482968.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Alstrom syndrome Pathogenic:3

Sep 13, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is not present in population databases (ExAC no frequency). This sequence change creates a premature translational stop signal (p.Ser2719Phefs*7) in the ALMS1 gene. It is expected to result in an absent or disrupted protein product. This variant has been observed in individual(s) with Alstrom syndrome (PMID: 25846608). It is also known as c.8150_8151insT in the literature. ClinVar contains an entry for this variant (Variation ID: 557063). Loss-of-function variants in ALMS1 are known to be pathogenic (PMID: 17594715). For these reasons, this variant has been classified as Pathogenic. -

Mar 09, 2018

Counsyl

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 16, 2022

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: ALMS1 c.8149dupT (p.Ser2717PhefsX7, also known as c.8155dupT/p.Ser2719PhefsX7) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory. The variant was absent in 249554 control chromosomes. c.8149dupT has been reported in the literature in individuals affected with Alstrom Syndrome (Marshall_2015). These data indicate that the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. Both laboratories classified the variant as pathogenic/likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

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: rs1553409691; hg19: chr2-73717233;