rs1555817157

Variant names:

• chr20-25339319-ATCTTCCTCAGGCG-A
• rs1555817157
• NM_001042472.3:c.211_223delCGCCTGAGGAAGA

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1 PP5_Moderate

The NM_001042472.3(ABHD12):​c.211_223delCGCCTGAGGAAGA​(p.Arg71TyrfsTer26) variant causes a frameshift change. The variant allele was found at a frequency of 0.00000137 in 1,461,888 control chromosomes in the GnomAD database, with no homozygous occurrence. It is difficult to determine the true allele frequency of this variant because it is of type DEL_BIG, and the frequency of such variant types in population databases may be underestimated and unreliable. Variant has been reported in ClinVar as Pathogenic (★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: ABHD12 NM_001042472.3 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 6.60
• Publications: 2 publications found

Genes affected

ABHD12 (HGNC:15868): (abhydrolase domain containing 12, lysophospholipase) This gene encodes an enzyme that catalyzes the hydrolysis of 2-arachidonoyl glycerol (2-AG), the main endocannabinoid lipid transmitter that acts on cannabinoid receptors, CB1 and CB2. The endocannabinoid system is involved in a wide range of physiological processes, including neurotransmission, mood, appetite, pain appreciation, addiction behavior, and inflammation. Mutations in this gene are associated with the neurodegenerative disease, PHARC (polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and cataract), resulting from an inborn error of endocannabinoid metabolism. Alternatively spliced transcript variants encoding different isoforms have been noted for this gene.[provided by RefSeq, Jan 2011]

ABHD12 Gene-Disease associations (from GenCC):

• PHARC syndrome

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Labcorp Genetics (formerly Invitae), PanelApp Australia, Orphanet, ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PP5: Variant 20-25339319-ATCTTCCTCAGGCG-A is Pathogenic according to our data. Variant chr20-25339319-ATCTTCCTCAGGCG-A is described in ClinVar as Pathogenic. ClinVar VariationId is 430695.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ABHD12	NM_001042472.3	c.211_223delCGCCTGAGGAAGA	p.Arg71TyrfsTer26	frameshift_variant	Exon 2 of 13	ENST00000339157.10	NP_001035937.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ABHD12	ENST00000339157.10	c.211_223delCGCCTGAGGAAGA	p.Arg71TyrfsTer26	frameshift_variant	Exon 2 of 13	2	NM_001042472.3	ENSP00000341408.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461888 Hom.: 0 AF XY: 0.00000138 AC XY: 1 AN XY: 727246

⚠️ 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: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1112008

Other (OTH) AF: 0.00 AC: 0 AN: 60396

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.002339), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

PHARC syndrome Pathogenic:1

Jun 30, 2017

Unit of Genetics and Genomics of Neuromuscular Diseases, Principe Felipe Research Center

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

The variant ABHD12:c.211_233del, was detected in homozygous in two related patients with PHARC syndrome. -

not provided Pathogenic:1

Dec 25, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

ClinVar contains an entry for this variant (Variation ID: 430695). This sequence change creates a premature translational stop signal (p.Arg71Tyrfs*26) in the ABHD12 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in ABHD12 are known to be pathogenic (PMID: 20797687). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with polyneuropathy, hearing loss, ataxia, retinitis pigmentosa and cataracts syndrome (PMID: 29571850). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		6.6
Mutation Taster		=2/198	disease causing (ClinVar)

Splicing

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

Other links and lift over

dbSNP: rs1555817157; hg19: chr20-25319955;