rs779366889

Positions:

• chr2-73451436-CTAAA-C

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.4914_4917del​(p.Asn1638LysfsTer4) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000372 in 1,613,044 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: ALMS1 NM_001378454.1 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 0.533

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 2-73451436-CTAAA-C is Pathogenic according to our data. Variant chr2-73451436-CTAAA-C is described in ClinVar as [Pathogenic]. Clinvar id is 550038.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-73451436-CTAAA-C is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ALMS1	NM_001378454.1	c.4914_4917del	p.Asn1638LysfsTer4	frameshift_variant	8/23	ENST00000613296.6	NP_001365383.1
ALMS1	NM_015120.4	c.4917_4920del	p.Asn1639LysfsTer4	frameshift_variant	8/23		NP_055935.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ALMS1	ENST00000613296.6	c.4914_4917del	p.Asn1638LysfsTer4	frameshift_variant	8/23	1	NM_001378454.1	ENSP00000482968	P3

Frequencies

GnomAD3 genomes AF: 0.00000661 AC: 1 AN: 151274 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000195

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

GnomAD3 exomes AF: 0.0000201 AC: 5 AN: 248262 Hom.: 0 AF XY: 0.00000741 AC XY: 1 AN XY: 134894

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000223

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000890

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461770 Hom.: 0 AF XY: 0.00000138 AC XY: 1 AN XY: 727194

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000101

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000661 AC: 1 AN: 151274 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 73852

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000195

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000189

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Alstrom syndrome Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Mar 22, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 30, 2024	This sequence change creates a premature translational stop signal (p.Asn1639Lysfs*4) in the ALMS1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in ALMS1 are known to be pathogenic (PMID: 17594715). This variant is present in population databases (rs779366889, gnomAD 0.03%). This premature translational stop signal has been observed in individual(s) with Alstrom syndrome and/or cone-rod dystrophy (PMID: 25846608, 26992781). ClinVar contains an entry for this variant (Variation ID: 550038). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	3billion	Sep 01, 2022	The variant is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: 0.002%). Frameshift variant is predicted to result in a loss or disruption of normal protein function through nonsense-mediated decay (NMD) or protein truncation. Multiple pathogenic variants are reported downstream of the variant. The variant was found to in trans with other pathogenic variant (3billion dataset). The variant has been reported at least twice as pathogenic with clinical assertions and evidence for the classification (ClinVar ID: VCV000550038 / PMID: 25846608). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -

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: rs779366889; hg19: chr2-73678563;